論文 - 三木　則尚

Impact of polyimide on the recycling of waste expanded polystyrene into flat‑sheet filtration membrane

Tutik Sriani, Muslim Mahardika, Norihisa Miki, Chandrawati Putri Wulandari, Gunawan Setia Prihandana

（Journal of Material Cycles and Waste Management）  2024年09月

研究論文（学術雑誌）, 査読有り

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Relationship Between Interoceptive Accuracy and Tactile Exploration Behavior

H. Aso, H. Ishizuka, T. Hiraki, Y. Minagawa, N. MIki

IEEE Access 12   93145 - 93151 2024年

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

This paper presents a novel finding suggesting that tactile exploration behaviors, with a focus on finger scanning motion, are influenced by interoception. Initially, we investigated finger motion for surface scanning across various precisely controlled surface patterns using microfabrication techniques. Participants were then categorized into two distinct groups based on whether their finger scanning speed depended on surface patterns. Subsequently, we assessed participants' interoception through a heart rate counting task. The identified groups correlated with levels of interoceptive accuracy, indicating a significant relationship between interoception and tactile-related behaviors. This discovery could have a profound impact on tactile research, as it suggests the need to consider interoception properties alongside conventional participant demographics such as age and gender in experimental design.

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Microfabricated Nitinol Stent Retrievers with a Micro-Patterned Surface

Kato S., Ban Y., Ota T., Miki N.

Micromachines （Micromachines）  15 （ 2 ）  2024年02月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り

　概要を見る

Stent retrievers are medical devices that are designed to physically remove blood clots from within the blood vessels of the brain. This paper focuses on microfabricated nitinol (nickel–titanium alloy) stent retrievers, which feature micro-patterns on their surface to enhance the effectiveness of mechanical thrombectomy. A thick film of nitinol, which was 20 µm in thickness, was sputtered onto a substrate with a micro-patterned surface, using electroplated copper as the sacrificial layer. The nitinol film was released from the substrate and then thermally treated while folded into a cylindrical shape. In vitro experiments with pig blood clots demonstrated that the micro-patterns on the surface improved the efficacy of blood clot retrieval.

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Reproducible reformation of a bilayer lipid membrane using microair bubbles

Hashimoto I., Osaki T., Sugiura H., Mimura H., Takamori S., Miki N., Takeuchi S.

Droplet （Droplet）  2 （ 3 ）  2023年07月

研究論文（学術雑誌）,  ISSN  27692159

　概要を見る

Planar bilayer lipid membranes (BLMs) are widely used as models for cell membranes in various applications, including drug discovery and biosensors. However, the nanometer-thick bilayer structure, assembled through hydrophobic interactions of amphiphilic lipid molecules, makes such BLM systems mechanically and electrically unstable. In this study, we developed a device to reform BLMs using a microair bubble. The device consists of a double well divided by a separator with a microaperture, where a BLM was formed by infusing a lipid-dispersed solvent and an aqueous droplet into each well in series. When the BLM ruptured, a microair bubble was injected from the bottom of the well to split the merged aqueous droplet at the microaperture, which resulted in the reformation of two lipid monolayers on the split droplets. By bringing the two droplets into contact, a new BLM was formed. An angled step design was introduced in the BLM device to guide the bubble and ensure the splitting of the merged droplet. We also elucidated the optimal bubble inflow rate for the reproducible BLM reformation. Using a 4-channel parallel device, we demonstrated the individual and repeatable reformation of BLMs. Our approach will aid the development of automated and arrayed BLM systems.

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Real-time quantitative characterization of ion channel activities for automated control of a lipid bilayer system

Ogishi K., Osaki T., Mimura H., Hashimoto I., Morimoto Y., Miki N., Takeuchi S.

Biosensors and Bioelectronics （Biosensors and Bioelectronics）  237 2023年10月

研究論文（学術雑誌）, 査読有り,  ISSN  09565663

　概要を見る

This paper describes a novel signal processing method to characterize the activity of ion channels on a lipid bilayer system in a real-time and quantitative manner. Lipid bilayer systems, which enable single-channel level recordings of ion channel activities against physiological stimuli in vitro, are gaining attention in various research fields. However, the characterization of ion channel activities has heavily relied on time-consuming analyses after recording, and the inability to return the quantitative results in real time has long been a bottleneck to incorporating the system into practical products. Herein, we report a lipid bilayer system that integrates real-time characterization of ion channel activities and real-time response based on the characterization result. Unlike conventional batch processing, an ion channel signal is divided into short segments and processed during the recording. After optimizing the system to maintain the same characterization accuracy as conventional operation, we demonstrated the usability of the system with two applications. One is quantitative control of a robot based on ion channel signals. The velocity of the robot was controlled every second, which was around tens of times faster than the conventional operation, in proportion to the stimulus intensity estimated from changes in ion channel activities. The other is the automation of data collection and characterization of ion channels. By constantly monitoring and maintaining the functionality of a lipid bilayer, our system enabled continuous recording of ion channels over 2 h without human intervention, and the time of manual labor has been reduced from conventional 3 h to 1 min at a minimum. We believe the accelerated characterization and response in the lipid bilayer systems presented in this work will facilitate the transformation of lipid bilayer technology toward a practical level, finally leading to its industrialization.

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ProtoHand: Solderless Prototyping of Electrical Circuits on a Soft Artificial Hand with Liquid Metal

Yamaguchi S., Nakano N., Hiraki T., Ishizuka H., Miki N.

IEEE Sensors Letters （IEEE Sensors Letters）  7 （ 3 ）  2023年03月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り

　概要を見る

In this letter, we propose and demonstrate ProtoHand, which is a soft artificial hand that can work as a universal platform for prototyping electrical circuits similar to a breadboard. ProtoHand is made of flexible and transparent polydimethyl siloxane. ProtoHand has multiple channels filled with liquid metal beneath the surface, like the blood vessels of a hand. Electric components, such as resistors and capacitors, can be inserted by piercing into ProtoHand and electrically connected via the conductive liquid metal. Soldering is unnecessary, and the parts can be removed without leakage of the liquid metal; therefore, prototyping of electric circuits can be performed on this soft hand in a reusable manner. ProtoHand will help the design of multifunctional robot hands and could also be an excellent educational tool.

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Easily Attach/Detach Reattachable EEG Headset with Candle-like Microneedle Electrodes

Kawana T., Zemba Y., Ichikawa R., Miki N.

Micromachines （Micromachines）  14 （ 2 ）  2023年02月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り

　概要を見る

To expand the applications of the electroencephalogram (EEG), long-term measurement, a short installation time, and little stress on the participants are needed. In this study, we designed, fabricated, and evaluated an EEG headset with three candle-like microneedle electrodes (CMEs). The user is able to detach and reattach the electrodes, enabling long-term measurement with little stress. The design of the CMEs was experimentally determined by considering the skin-to-electrode impedance and user comfort. An EEG was successfully measured from areas with a high hair density without any preparation. The installation time was shorter than 60 s and the electrodes could be detached and reattached. The headset was designed such that the discomfort caused by its ear pads was higher than that caused by the electrodes. In 1 h experiments, the participants did not feel pain and the detachment of the CMEs was found to improve the comfort level of the participants in most cases. A successful demonstration of the long-term measurement of EEGs while watching a whole movie verified that the developed EEG headset with CMEs is applicable for EEG measurement in a variety of applications.

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Stretchable Strain Sensor with Small but Sufficient Adhesion to Skin

Nishikawa T., Yamane H., Matsuhisa N., Miki N.

Sensors （Sensors）  23 （ 4 ）  2023年02月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り,  ISSN  14248220

　概要を見る

Stretchable strain sensors that use a liquid metal (eutectic gallium–indium alloy; E-GaIn) and flexible silicone rubber (Ecoflex) as the support and adhesive layers, respectively, are demonstrated. The flexibility of Ecoflex and the deformability of E-GaIn enable the sensors to be stretched by 100%. Ecoflex gel has sufficiently large adhesion force to skin, even though the adhesion force is smaller than that for commercially available adhesives. This enables the sensor to be used for non-invasive monitoring of human motion. The mechanical and electrical properties of the sensor are experimentally evaluated. The effectiveness of the proposed sensors is demonstrated by monitoring joint movements, facial expressions, and respiration.

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Handshake Feedback in a Haptic Glove Using Pouch Actuators

Yamaguchi S., Hiraki T., Ishizuka H., Miki N.

Actuators （Actuators）  12 （ 2 ）  2023年02月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り

　概要を見る

In this paper, we propose and demonstrate a haptic device with liquid-pouch motors that can simulate a handshake. Because handshakes involve contact of the palms or soft skin, handshake simulation requires the haptic device to provide pressure onto specific areas of the palm with soft contact. This can be achieved with thermally driven liquid-pouch motors, which inflate and deflate when a low-boiling-point liquid, here Novec™ 7000, evaporates and condenses, respectively. Due to the simplicity of the soft actuator system, this haptic glove is lightweight and conformable. To design the haptic glove, we experimentally investigated the contact region and strength in handshakes, which led to an optimal number, size and position for the liquid-pouch motors. Sensory experiments with human subjects verified that the designed haptic glove successfully simulated handshakes.

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Micromanufactured Tactile Samples for Characterization of Rough and Dry Tactile Perception

Yanagibashi K., Miki N.

Micromachines （Micromachines）  13 （ 10 ）  2022年10月

　概要を見る

The quantitative characterization of tactile perception, which is crucial in the design of tactile devices, requires the tested samples to have individually and precisely controlled properties associated with the senses. In this work, we microfabricated such tactile samples and then quantitatively characterized tactile perception with a focus on roughness and dryness. In the roughness perception experiments, the tactile samples had a stripe pattern with ridge and groove widths that were individually controlled. The experimental results revealed that the feeling of roughness was more dominated by the width of the groove than that of the ridge and that conventionally used roughness parameters such as (Formula presented.) and (Formula presented.) were not sufficient for predicting roughness perception. In the dryness perception experiments, the tactile samples had a micropattern formed by dry etching and an array of squares. The experimental results revealed that dry perception had different properties when the feature sizes were below and above 30 µm, which may have been due to the effect of adhesion on friction. The proposed tactile samples were suitable for the quantitative and precise characterization of tactile perception.

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Machine-Learning-Based Fine Tuning of Input Signals for Mechano-Tactile Display

Yamanaka S., Nagatomo T., Hiraki T., Ishizuka H., Miki N.

Sensors （Sensors）  22 （ 14 ） 5299 2022年07月

研究論文（学術雑誌）, 共著, 最終著者, 責任著者, 査読有り,  ISSN  14248220

　概要を見る

Deducing the input signal for a tactile display to present the target surface (i.e., solving the inverse problem for tactile displays) is challenging. We proposed the encoding and presentation (EP) method in our prior work, where we encoded the target surface by scanning it using an array of piezoelectric devices (encoding) and then drove the piezoelectric devices using the obtained signals to display the surface (presentation). The EP method reproduced the target texture with an accuracy of over 80% for the five samples tested, which we refer to as replicability. Machine learning is a promising method for solving inverse problems. In this study, we designed a neural network to connect the subjective evaluation of tactile sensation and the input signals to a display; these signals are described as time-domain waveforms. First, participants were asked to touch the surface presented by the mechano-tactile display based on the encoded data from the EP method. Then, the participants recorded the similarity of the surface compared to five material samples, which were used as the input. The encoded data for the material samples were used as the output to create a dataset of 500 vectors. By training a multilayer perceptron with the dataset, we deduced new inputs for the display. The results indicate that using machine learning for fine tuning leads to significantly better accuracy in deducing the input compared to that achieved using the EP method alone. The proposed method is therefore considered a good solution for the inverse problem for tactile displays.

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Pressure-controlled ultrasound probe for reliable imaging in breast cancer diagnosis

Matsumoto Y., Katsumura A., Miki N.

Japanese Journal of Applied Physics （Japanese Journal of Applied Physics）  61 （ SD ） SD1035 2022年05月

研究論文（学術雑誌）, 共著, 最終著者, 査読有り,  ISSN  00214922

　概要を見る

Breast cancer is the most common cancer among women worldwide, with over 2 million new cases diagnosed each year. Early detection can be achieved by screening examinations such as mammography and ultrasonography. The latter has demonstrated advantages such as safety and sensitivity to dense breasts, but is often performed as a follow-up test after abnormal findings at mammography or on palpation. Indeed, the technique shows limitations of operator-dependence and non-reproducibility, since the quality of imaging is highly dependent on the skill of the technologist performing the examination. We therefore designed a diagnosis-assisting device comprising piezoresistive sensors of microscale thickness that can be attached to the ultrasound transducer. The operator is informed when excessive pressure is detected, allowing correction of the transducer position. Finally, we fabricated a breast phantom including tumors from agar and collagen to assess the effectiveness of the device.

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Study Effect of nAg Particle Size on the Properties and Antibacterial Characteristics of Polysulfone Membranes

Prihandana G.S., Sriani T., Muthi’ah A.D., Machmudah A., Mahardika M., Miki N.

Nanomaterials （MDPI）  12 （ 3 ） 388 2022年01月

研究論文（国際会議プロシーディングス）, 共著, 最終著者, 査読有り

　概要を見る

Polysulfone ultrafiltration membranes were fabricated using various sizes (20, 40, and 90–210 nm) of silver nanoparticles (nAg) blended in a dope solution. To characterize the performance and properties of the prepared membranes, scanning electron microscopy (SEM), water contact angle, protein separation, water flux, and antibacterial tests were conducted. The characterization results revealed that when nAg particles (20 nm) were blended into the base polymer PSF, the PSF/nAg blended membrane had the lowest contact angle (58.5◦ ) and surface energy (110.7 mN/m). When experimenting with ultrafiltration using protein solutions, bare PSF and PSF/nAg-20 blended membranes gave similar values of protein rejection: 93% of bovine serum albumin (BSA) and 70% of lysozyme rejection. Furthermore, SEM studies showed that the surface pore size was reduced by adding 20 nm nAg particles in the casting solution. Most importantly, the introduction of 40 nm nAg particles reduced the growth of bacterial colonies on the membrane surface by up to 72%. These findings revealed that nAg particles are expected to be a potential modifier for the fabrication of an ultrafiltration membrane.

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Direct Wiring of Liquid Metal on an Ultrasoft Substrate Using a Polyvinyl Alcohol Lift-off Method

Murakami K., Tochinai R., Tachibana D., Isano Y., Matsuda R., Nakamura F., Kurotaki Y., Isoda Y., Yamane M., Sugita Y., Fukuda J., Ueno K., Miki N., Fuchiwaki O., Ota H.

ACS Applied Materials and Interfaces （ACS Applied Materials and Interfaces）  14 （ 5 ） 7241 - 7251 2022年02月

研究論文（学術雑誌）, 査読有り,  ISSN  19448244

　概要を見る

In recent years, wiring and system construction on ultrasoft materials such as biological tissues and hydrogels have been proposed for advanced wearable devices, implantable devices, and soft robotics. Among the soft conductive materials, Ga-based liquid metals (LMs) are both biocompatible and ultrasoft, making them a good match for electrodes on the ultrasoft substrates. However, gels and tissues are softer and less wettable to the LMs than conventional soft substrates such as Ecoflex and polydimethylsiloxane. In this study, we demonstrated the transfer of LM paste composed of Ga-based LM and Ni nanoparticles onto ultrasoft substrates such as biological tissue and gels using sacrificial polyvinyl alcohol (PVA) films. The LM paste pattern fabricated on the PVA film adhered to the ultrasoft substrate along surface irregularities and was transferred without being destroyed by the PVA film before the PVA's dissolution in water. The minimum line width that could be wired was approximately 165 μm. Three-dimensional wiring, such as the helical structure on the gel fiber surface, is also possible. Application of this transfer method to tissues using LM paste wiring allowed the successful stimulation of the vagus nerve in rats. In addition, we succeeded in transferring a temperature measurement system fabricated on a PVA film onto the gel. The connection between the solid-state electrical element and the LM paste was stable and maintained the functionality of the temperature-sensing system. This fundamental study of wiring fabrication and system integration can contribute to the development of advanced electric devices based on ultrasoft substrates.

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Unsupervised Learning Enables Extraction of Tactile Information from Text Database

T. Nagatomo, T. Hiraki, H. Ishizuka, N. Miki

IEEE Access （IEEE）  11   101155 - 101166 2021年11月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り

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Pump‐free microfluidic hemofiltration device

Ito T., Ota T., Kono R., Miyaoka Y., Ishibashi H., Komori M., Yasukawa A., Kanno Y., Miki N.

Micromachines （Micromachines）  12 （ 8 ） 992 2021年08月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

Hemofiltration removes water and small molecules from the blood via nanoporous filtering membranes. This paper discusses a pump‐free hemofiltration device driven by the pressure dif-ference between the artery and the vein. In the design of the filtering device, oncotic pressure needs to be taken into consideration. Transmembrane pressure (TMP) determines the amount and direc-tion of hemofiltration, which is calculated by subtracting the oncotic pressure from the blood pres-sure. Blood pressure decreases as the channels progress from the inlet to the outlet, while oncotic pressure increases slightly since no protein is removed from the blood to the filtrate in hemofiltra-tion. When TMP is negative, the filtrate returns to the blood, i.e., backfiltration takes place. A small region of the device with negative TMP would thus result in a small amount of or even zero filtrates. First, we investigated this phenomenon using in vitro experiments. We then designed a hemofiltra-tion system taking backfiltration into consideration. We divided the device into two parts. In the first part, the device has channels for the blood and filtrate with a nanoporous membrane. In the second part, the device does not have channels for filtration. This design ensures TMP is always positive in the first part and prevents backfiltration. The concept was verified using in vitro experiments and ex vivo experiments in beagle dogs. Given the simplicity of the device without pumps or electrical components, the proposed pump‐free hemofiltration device may prove useful for either implantable or wearable hemofiltration.

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The effect of haptic stimulation simulating heartbeats on the regulation of physiological responses and prosocial behavior under stress: The influence of interoceptive accuracy

Xu M., Tachibana T., Suzuki N., Hoshino E., Terasawa Y., Miki N., Minagawa Y.

Biological Psychology （Biological Psychology）  164   108172 2021年08月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  03010511

　概要を見る

Research has discovered the modulatory effect of peripheral stimulation simulating altered bodily signals on emotion. Whether such an effect varies depending on one's interoceptive accuracy (IAc) remains unclear. Therefore, we provided haptic stimulation simulating participants’ slowed-down heartbeats or no stimulation while they engaged in socially stressful tasks to examine whether participants reacted differently depending on their IAc. Results showed that haptic stimulation exhibited the opposite effect on participants with different levels of IAc for both heart rate and heart rate variability (HRV). When receiving the stimulation, participants with higher IAc showed less increased heart rate and more elevated HF than participants with lower IAc. In contrast, in the absence of stimulation, an opposite pattern of response depending on participants’ IAc was observed. The modulatory effect of stimuli and IAc on prosocial behavior was not significant. Individual differences in IAc were shown to affect how one perceives/responds to altered bodily signals.

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Precision electropolishing on fabricating ss 316l microchannel – a taguchi approach

Setyawan M.A., Mahardika M., Sriani T., Miki N., Prihandana G.S.

International Journal on Engineering Applications （International Journal on Engineering Applications）  9 （ 4 ） 209 - 216 2021年

研究論文（学術雑誌）, 共著,  ISSN  22812881

　概要を見る

This paper presents the fabrication of a microchannel on stainless steel 316L (SS 316L) by electropolishing method. Machining parameters such as applied voltage, concentration of NaCl in the electrolyte solution and machining gap between tool and workpiece have been optimized in this electropolishing process. The Taguchi method is adopted to ascertain the optimum process parameters in order to increase maximum material removal rate using L9 orthogonal array. Pareto analysis of variance is employed in order to analyze the machining process parameters to the material removal rate. The result shows that the optimal parameters to achieve the maximum material removal rate is by using a combination of 10 V as applied voltage, NaCl concentration of 15 wt.%, and setting 1 cm as the machining gap. It has been also found out that in order to have relatively high material removal without sacrificing the surface quality and the geometrical accuracy of the microchannel produced, applied voltage at 7 V, NaCl concentration of 7 wt.% and machining gap of 3 cm is the best combination of the electropolishing parameters. Copyright © 2021 Praise Worthy Prize S.r.l.-All rights reserved.

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Fluid interfacial energy drives the emergence of three-dimensional periodic structures in micropillar scaffolds

Yasuga H., Iseri E., Wei X., Kaya K., Di Dio G., Osaki T., Kamiya K., Nikolakopoulou P., Buchmann S., Sundin J., Bagheri S., Takeuchi S., Herland A., Miki N., van der Wijngaart W.

Nature Physics （Nature Physics）  17 （ 7 ） 794 - 800 2021年03月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  17452473

　概要を見る

Structures that are periodic on a microscale in three dimensions are abundant in nature, for example, in the cellular arrays that make up living tissue. Such structures can also be engineered, appearing in smart materials1–4, photonic crystals5, chemical reactors6, and medical7 and biomimetic8 technologies. Here we report that fluid–fluid interfacial energy drives three-dimensional (3D) structure emergence in a micropillar scaffold. This finding offers a rapid and scalable way of transforming a simple pillar scaffold into an intricate 3D structure that is periodic on a microscale, comprising a solid microscaffold, a dispersed fluid and a continuous fluid. Structures generated with this technique exhibit a set of unique features, including a stationary internal liquid–liquid interface. Using this approach, we create structures with an internal liquid surface in a regime of interest for liquid–liquid catalysis. We also synthesize soft composites in solid, liquid and gas combinations that have previously not been shown, including actuator materials with temperature-tunable microscale pores. We further demonstrate the potential of this method for constructing 3D materials that mimic tissue with an unprecedented level of control, and for microencapsulating human cells at densities that address an unresolved challenge in cell therapy.

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Artificial Cell Membrane Sensors with Membrane Proteins

Y. Ito, T. Osaki, N. Miki, S. Takeuchi

表面と真空 2021年04月

研究論文（学術雑誌）, 共著, 査読有り

A lipid-bilayer-on-a-cup device for pumpless sample exchange

Yoshihisa Ito, Yusuke Izawa, Toshihisa Osaki, Koki Kamiya, Nobuo Misawa, Satoshi Fujii, Hisatoshi Mimura, Norihisa Miki, Shoji Takeuchi

Micromachines （MDPI）  11 （ 12 ） 1123 2020年12月

研究論文（学術雑誌）, 共著, 査読有り

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Lipid Bilayer Array: Rapid and Resilient Detection of Toxin Pore Formation Using a Lipid Bilayer Array

Yoshihisa Ito Toshihisa Osaki Koki Kamiya Tetsuya Yamada Norihisa Miki Shoji Takeuchi

Small （Wiley）  16   202005550 2020年11月

研究論文（学術雑誌）, 共著, 査読有り

Capturing human perceptual and cognitive activities via event-related potentials measured with candle-like dry microneedle electrodes

Yuri Yoshida, Takumi Kawana, Eiichi Hoshino, Yasuyo Minagawa, Norihisa Miki

Micromachines （MDPI）  11 （ 6 ） 556 2020年05月

研究論文（学術雑誌）, 共著, 査読有り

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Tactile samples with variable surface textures to investigate tactile perception characteristic

M. Kawazoe, N. Miki

Journal of Micromechanics and Microengineering （IOP）  30 （ 10 ） 105011 2020年07月

研究論文（学術雑誌）, 共著, 査読有り

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コロナ禍における技術者倫理

三木則尚

機械の研究 （養賢堂）  72 （ 12 ） 927 - 934 2020年11月

研究論文（学術雑誌）, 単著

インプラント人工透析システムの実現に向けて

三木則尚

エレクトロニクス実装学会誌 23 （ 5 ） 393 - 397 2020年08月

研究論文（学術雑誌）, 単著

Design and characterization of an EEG-Hat for reliable EEG measurements

T. Kawana, Y. Yoshida, Y. Kudo, C. Iwatani, N. Miki

Micromachines （MDPI）  11 （ 7 ） 635 2020年07月

研究論文（学術雑誌）, 共著, 査読有り

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Ion concentration measurement using synthetic microfluidic papers

Kamiya, H., Yasuga, H. & Miki, N

PLOS ONE 15 （ 11 ） e0242188 2020年11月

研究論文（学術雑誌）, 共著, 査読有り

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Microfluidic screening system based on boron-doped diamond electrodes and dielectrophoretic sorting for directed evolution of NAD(P)-dependent oxidoreductases

Goto H., Kanai Y., Yotsui A., Shimokihara S., Shitara S., Oyobiki R., Fujiwara K., Watanabe T., Einaga Y., Matsumoto Y., Miki N., Doi N.

Lab on a Chip （Lab on a Chip）  20 （ 4 ） 852 - 861 2020年01月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  14730197

　概要を見る

This journal is © The Royal Society of Chemistry. We report the development of a micro total analysis system (μTAS) based on electrochemical measurements and dielectrophoretic sorting for screening of NAD(P)-dependent oxidoreductases. In this system, the activity of enzymes immobilized on microbeads, together with their encoding DNA, can be measured with a boron-doped diamond (BDD) electrode in each compartment (∼30 nL) of the microfluidic system. The 30 nL droplets containing microbead-displayed genes of enzymes with higher activity can then be recovered by dielectrophoretic sorting. Previously, we developed the NAD(P)H-measuring device containing the BDD electrode for high-throughput measurement of the activity of NAD(P)-dependent oxidoreductases. In this study, we fabricated an encapsulating device and a droplet-sorting device for nanoliter-size droplets, for the first time, and then combined these three devices to construct a μTAS for directed evolution of NAD(P)-dependent oxidoreductases. We confirmed that this system works by proof-of-principle experiments and successfully applied this system for screening of randomized libraries of NAD-dependent dehydrogenases.

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Synthesis of sub-micrometer biphasic Au-AuGa2 / Liquid Metal frameworks

Romain David, Norihisa Miki

Nanoscale （Royal Society of Chemistry）  11   21419 - 21432 2019年10月

研究論文（学術雑誌）, 共著, 査読有り

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Connecting mechanism for artificial blood vessels with high biocompatibility

Watanabe A., Miki N.

Micromachines （Micromachines）  10 （ 7 ）  2019年07月

　概要を見る

© 2019 by the authors. This paper proposes a connecting mechanism for artificial vessels, which can be attached/detached with ease and does not deteriorate the biocompatibility of the vessels at the joint. The inner surface of the artificial vessels is designed to have high biocompatibility. In order to make the best of the property, the proposed connecting mechanism contacts and fixes the two artificial vessels whose contacting edges are turned inside out. In this manner, blood flowing inside the vessels only has contact with the biocompatible surface. The biocompatibility, or biofouling at the joint was investigated after in vitro blood circulation tests for 72 h with scanning electron microscopy. Blood coagulation for a short term (120 min) was evaluated by activated partial thromboplastin time (APTT). A decrease of APTT was observed, although it was too small to conclude that the connector augmented the blood coagulation. The micro dialysis device which our group has developed as the artificial kidney was inserted into the blood circulation system with the connector. Decrease of APTT was similarly small. These experiments verified that the proposed connector can be readily applicable for implantable medical devices.

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A thermal tactile sensation display with controllable thermal conductivity

Hirai S., Miki N.

Micromachines （Micromachines）  10 （ 359 ）  2019年05月

共著, 査読有り

　概要を見る

© 2019 by the authors. We demonstrate a thermal tactile sensation display that can present various thermal sensations, namely cold/cool/warm/hot feelings, by varying the effective thermal conductivity of the display. Thermal sensation is one of the major tactile sensations and needs to be further investigated for advanced virtual reality/augmented reality (VR/AR) systems. Conventional thermal sensation displays present hot/cold sensations by changing the temperature of the display surface, whereas the proposed display is the first one that controls its effective thermal conductivity. The device contains an air cavity and liquid metal that have low and high thermal conductivity, respectively. When the liquid metal is introduced to fill up the air cavity, the apparent thermal conductivity of the device increases. This difference in the thermal conductivity leads to the users experiencing different thermal tactile sensations. Using this device, the threshold to discriminate the effective thermal conductivity was experimentally deduced for the first time. This thermal tactile display can be a good platform for further study of thermal tactile sensation.

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Automatic generation system of cell-sized liposomes

Gotanda M., Kamiya K., Osaki T., Miki N., Takeuchi S.

Sensors and Actuators, B: Chemical （Sensors and Actuators, B: Chemical）  292   57 - 63 2019年04月

研究論文（学術雑誌）, 査読有り,  ISSN  09254005

　概要を見る

© 2019 Elsevier B.V. Artificial cell membranes such as liposomes and lipid vesicles have been developed using microfluidic technologies. These technologies have advantages for generating cell-sized liposomes, including a monodispersed and asymmetric lipid composition. Cell-sized asymmetric liposomes with various combinations of asymmetric lipid leaflets are sequentially produced using an improved pulsed-jetting device with the six wells arranged on a circular rotation table by manual manipulation. In this study, we reveal optimal parameters of rotation speed and jetting timing for the cell-sized liposome formation using an automatic sequential liposome generation system driven by a stepping motor. First, we optimize the rotation speed of the stepping motor for forming the planar lipid bilayer under control of a microcomputer. Next, we generate cell-sized liposomes using this automated system at the optimized rotation speed. This automatic system will contribute to high-throughput investigations of membrane protein activities and functions using the electrophysiological or the asymmetric liposome analyses.

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Activation of cell migration via morphological changes in focal adhesions depends on shear stress in MYCN-amplified neuroblastoma cells

Hiraiwa T., Yamada T., Miki N., Funahashi A., Hiroi N.

Journal of the Royal Society Interface （Journal of the Royal Society Interface）  16 （ 152 ） 20180934 2019年03月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  17425689

　概要を見る

© 2019 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Neuroblastoma is the most common solid tumour of childhood, and it metastasizes to distant organs. However, the mechanism of metastasis, which generally depends on the cell motility of the neuroblastoma, remains unclear. In many solid tumours, it has been reported that shear stress promotes metastasis. Here, we investigated the relationship between shear stress and cell motility in the MYCN-amplified human neuroblastoma cell line IMR32, using a microfluidic device. We confirmed that most of the cells migrated downstream, and cell motility increased dramatically when the cells were exposed to a shear stress of 0.4 Pa, equivalent to that expected in vivo. We observed that the morphological features of focal adhesion were changed under a shear stress of 0.4 Pa. We also investigated the relationship between malignancy and the motility of IMR32 cells under shear stress. Decreasing the expression of MYCN in IMR32 cells via siRNA transfection inhibited cell motility by a shear stress of 0.4 Pa. These results suggest that MYCN-amplified neuroblastoma cells under high shear stress migrate to distant organs due to high cell motility, allowing cell migration to lymphatic vessels and venules.

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Graphene-based wireless tube-shaped pressure sensor for in vivo blood pressure monitoring

Inoue N., Koya Y., Miki N., Onoe H.

Micromachines （Micromachines）  10 （ 2 ）  2019年02月

　概要を見る

© 2019 by the authors. We propose a wireless pressure sensor composed of a graphene sheet and a transmitter coil integrated with a polydimethylsiloxane (PDMS) tube. The pressure inside the tube was monitored wirelessly using an external receiver coil. We then monitored the typical blood pressure range, 12-20 kPa, using this fabricated sensor by changing the turn number of the receiver coil and the overlapping length of the coils. Furthermore, we demonstrated wireless blood pressure measurement by connecting our sensor to the blood vessel of a rat. Our results suggested that this sensor can be easily inserted between an implantable medical device and blood vessels for in vivo blood pressure monitoring. The proposed wireless pressure sensor could also be suitable for monitoring in vivo implanted medical systems, such as artificial organs and pump systems.

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Tooth-inspired tactile sensor for detection of multidirectional force

Ridzuan N., Miki N.

Micromachines （Micromachines）  10 （ 1 ） 18 2018年12月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the authors. The anatomy of a tooth was the inspiration for this tactile sensor study. The sensor consisted of a pole that was fixed in the middle of an acrylic base using a viscoelastic silicone elastomer. Four strain gauges were fixed three-dimensionally around the pole to detect its movement, which was formed in a single step in the assembly. When the load was applied to the side of the pole, the strain gauges were bent or released, depending on the direction of the applied load and the position of the strain gauges. The sensor device had the sensitivity of 0.016 mm -1 and 0.313 N -1 against the resistance change ratio. For the load detection experiment, a consistent pattern of full sine-curve, with a constant resistance change for the angles, was obtained for all of the four strain gauges, which confirmed the reliability of the sensor device to detect the direction of applied load. The amplitudes of the resistance change ratio remained to be consistent after loading-unloading processes at the frequency of 0.05-0.25 Hz.

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Reduction of parasitic capacitance of a PDMS capacitive force sensor

Nagatomo T., Miki N.

Micromachines （Micromachines）  9 （ 11 ） 570 2018年11月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the authors. Polymer-based flexible micro electro mechanical systems (MEMS) tactile sensors have been widely studied for a variety of applications, such as medical and robot fields. The small size and flexibility are of great advantage in terms of accurate measurement and safety. Polydimethylsiloxane (PDMS) is often used as the flexible structural material. However, the sensors are likely subject to large parasitic capacitance noise. The smaller dielectric constant leads to smaller influences of parasitic capacitance and a larger signal-to-noise ratio. In this study, the sensor underwent ultraviolet (UV) exposure, which changes Si-CH3 bonds in PDMS to Si-O, makes PDMS nanoporous, and leads to a low dielectric constant. In addition, we achieved further reduction of the dielectric constant of PDMS by washing it with an ethanol-toluene buffer solution after UV exposure. This simple but effective method can be readily applicable to improve the signal-to-noise ratio of PDMS-based flexible capacitive sensors. In this study, we propose reduction techniques for the dielectric constant of PDMS and applications for flexible capacitive force sensors.

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Quantitative analysis of sensitivity to Wnt3a gradient in determination of the pole-to-pole axis of mitotic cells by using a microfluidic device

T. Hiraiwa, Y. Nakai, T.G. Yamada, R. Tanimoto, H. Kimura, Y. Matsumoto, N. Miki, N. Hiroi, A. Funahashi

FEBS Open Bio （FEBS Press and John Wiley & Sons Ltd.）  2018年

研究論文（学術雑誌）, 共著, 査読有り

Tunable Noble Metal Thin Films on Ga Alloys via Galvanic Replacement

David R., Miki N.

Langmuir （Langmuir）  34 （ 36 ） 10550 - 10559 2018年08月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  07437463

　概要を見る

Copyright © 2018 American Chemical Society. Room-temperature liquid metals such as GaInSn or EGaIn present the most attractive properties for soft and highly stretchable electronics. Recently, several methods have been investigated to functionalize the surface of the liquid metal via coatings and encapsulation. However, most can hardly be extended to other samples than droplets. In this study, we focus on the tunability of the process of galvanic replacement of Ga alloys with gold to form thin-film encapsulation. We characterized in-depth the obtainable composition and structure of a noble metal shell formed on the liquid metal via scanning electron microscopy, energy-dispersive X-ray, and topographic laser microscopy and highlighted the change in mechanism of galvanic replacement in different pH ranges. We showed the tunability of the surface morphology selection of different pH ranges, the solutions concentrations, and the reaction time. The adjustment of the pH of KAuBr4 solution to the preferential Ga2O3-free domain led to the successful formation of a sub-micrometer thin uniform coating with more than 60% of Au and reduced level of oxygen from 30% down to 10%. We finally demonstrated the effect of the coating composition on the electrical properties of the liquid metal using a simple and fast phase-drop measurement setup on the droplet and microchannels. A high correlation between the amount of noble metal deposited and the electrical properties of the droplets was demonstrated.

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Fatigue assessment by blink detected with attachable optical sensors of dye-sensitized photovoltaic cells

Horiuchi R., Ogasawara T., Miki N.

Micromachines （Micromachines）  9 （ 6 ） 310 2018年06月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the authors. This paper demonstrates fatigue assessment based on eye blinks that are detected by dye-sensitized photovoltaic cells. In particular, the sensors were attached to the temple of eyeglasses and positioned at the lateral side of the eye. They are wearable, did not majorly disturb the user's eyesight, and detected the position of the eyelid or the eye state. The optimal location of the sensor was experimentally investigated by evaluating the detection accuracy of blinks. We conducted fatigue assessment experiments using the developed wearable system, or smart glasses. Several parameters, including the frequency, duration, and velocity of eye blinks, were extracted as fatigue indices. Successful fatigue assessment by the proposed system will be of great benefit for maximizing performance and maintenance of physical/mental health.

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Development of a fully flexible sheet-type tactile display based on electrovibration stimulus

Ishizuka H., Hatada R., Cortes C., Miki N.

Micromachines （Micromachines）  9 （ 5 ） 230 2018年05月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the author. Tactile displays have been extensively studied for several decades. However, owing to their bulkiness and stiffness, it has been difficult to integrate these displays with information devices to enable tactile communication between the devices and their users. This paper proposes a novel sheet-type electrovibration tactile display that consists of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate conductive layers and an insulation layer of polydimethylsiloxane. The tactile display is sufficiently thin and flexible for attaching onto various surfaces. In this study, the tactile display was micro-fabricated and characterized through experiments. The experimental results indicated that the tactile display exhibited good durability under bending and that it could present various tactile sensations depending on the type of voltage waveform. In addition, the effect of using a combination of electrovibration and thermal stimuli was also demonstrated. The sheet-type display was attached onto a Peltier element; the thinness of the structure enabled the display to conform to the element and ensure good heat transfer. In the experiment, subjects were asked to scan the display with their fingertips. The results showed that multiple tactile stimuli were also successfully perceived by the subjects.

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Sequential generation of asymmetric lipid vesicles using a pulsed-jetting method in rotational wells

Gotanda M., Kamiya K., Osaki T., Fujii S., Misawa N., Miki N., Takeuchi S.

Sensors and Actuators, B: Chemical （Sensors and Actuators, B: Chemical）  261   392 - 397 2018年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  09254005

　概要を見る

© 2018 Elsevier B.V. Current methods of generating asymmetric lipid vesicles produce only single types of vesicles, which poses a challenge for investigation of vesicles with different lipid leaflet combinations using a single device. Here, we describe a device for sequentially generating asymmetric lipid giant vesicles (GVs) with various combinations of asymmetric lipid leaflets. Various combinations of planar asymmetric lipid bilayers are formed by sliding and contacting the water in oil (phospholipid) (W/O) droplets in the collecting and jetting wells of our device. Next, we generate asymmetric lipid vesicles using a pulsed-jetting method. We sequentially generate three types of GVs: two asymmetric GVs containing fluorescent-conjugated phospholipids (either (i) rhodamine or (ii) BODIPY) on the outer leaflet, and (iii) a symmetric GV with phosphatidylcholine (PC) on the inner and outer leaflets. The use of asymmetric GVs with various combinations of asymmetric lipid leaflets reveals that increase in membrane phosphatidylethanolamine (PE) concentration influences cinnamycin activity and promotes the phospholipid flip-flop dynamics. This system will be useful for investigating activities of proteins or peptides on GV membranes with various combinations of lipid leaflets.

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Self-generation of two-dimensional droplet array using oil-water immiscibility and replacement

Yasuga H., Kamiya K., Takeuchi S., Miki N.

Lab on a Chip （Lab on a Chip）  18 （ 7 ） 1130 - 1137 2018年03月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  14730197

　概要を見る

© 2018 The Royal Society of Chemistry. Two-dimensional (2D) microdroplet arrays with indexed sample concentration gradients have been receiving considerable attention for high-throughput biological and medical analyses. However, the preparation of such an array by conventional methods mandates precise pipetting and/or pumping. In this paper, we introduce a method to spontaneously generate 2D-arrayed aqueous droplets using a well array, for which coarse pipetting is sufficient. The wells are connected in rows and columns via narrow channels. Aqueous solutions impregnated in the well array are split into droplets in every single well as a subsequently introduced immiscible solvent self-propagates and divides the solution at the channels. A concentration gradient of the samples can be formed across the connected solution in the well array; once droplets are generated, each droplet possesses a different sample concentration depending on its position in the array. We experimentally determined the optimal well dimensions and solvent species to obtain a high yield of droplet generation. We next demonstrated a 2D droplet array with a two-sample concentration gradient. Finally, the applicability of the system was demonstrated through a cell viability assay using a sample that induced apoptosis. We believe the proposed method contributes to simplification and miniaturization of the system to generate droplet arrays and thus is applicable to biological and medical analysis.

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Development of a triple-coaxial flow device for fabricating a hydrogel microtube and its application to bioremediation

Fujimoto K., Higashi K., Onoe H., Miki N.

Micromachines （Micromachines）  9 （ 2 ） 76 2018年02月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the authors. This paper demonstrates a triple-coaxial flow device to continuously produce a hydrogel microtube using a microfluidic technique. The hydrogel microtube can encapsulate a microbial suspension, while allowing the diffusion of oxygen and nutrients into the microtube and preventing microbes from passing into or out of the microtube. The microtubes also enable the collection of the microbes after task completion without contaminating the environment. In our previous study, we used a double-coaxial flow device to produce the microtubes, but continuous production was a challenge. In the present study, we developed a microfluidic device that fabricates a triple-coaxial flow to enable continuous production of the microtubes. Here, we characterize the production capacity of the microtubes along with their properties and demonstrate bioremediation using microtubes encapsulating a microbial suspension.

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Well-controlled cell-trapping systems for investigating heterogeneous cell-cell interactions

K. Kamiya, Y. Abe, K. Inoue, T. Osaki, R. Kawano, N. Miki, S. Takeuchi

Advanced Healthcare Materials 7   1701208 (9 pages) 2018年01月

研究論文（学術雑誌）, 共著, 査読有り

Hydrogel fiber cultivation method for forming bacterial cellulose microspheres

Higashi K., Miki N.

Micromachines （Micromachines）  9 （ 36 ）  2018年01月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

© 2018 by the authors. Forming microspheres or microbeads from nanofibrous materials has recently attracted research interest for their applications in various fields, because these structures greatly impact cellular behaviors and functions. However, conventional methods of preparing microspheres or microbeads have limitations, such as limited variety of material. Here, we propose a new fabrication process for forming a nanofibrous microsphere composed of bacterial cellulose (BC), which is synthesized through fermentation by specific bacteria. The process uses a hydrogel fiber containing spherical cavities. The bacteria encapsulated into the cavities produce BC, resulting in the formation of BC microspheres. Because of its simplicity, robustness, and cost-effectiveness, this process is promising for applications, such as in biochemical engineering and cell delivery systems.

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Stiffness-tunable device encapsulating magnetorheological fluids in a thin flexible polymer structure

H. Ishizuka, N. Miki

Mechanical Engineering Journal 5   17-00383 2018年01月

研究論文（学術雑誌）, 共著, 査読有り

Suppression of sloshing by utilizing surface energy and geometry in microliter cylindrical well

Izawa Y., Osaki T., Kamiya K., Fujii S., Misawa N., Takeuchi S., Miki N.

Sensors and Actuators, B: Chemical （Sensors and Actuators, B: Chemical）  258   1036 - 1041 2017年12月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  09254005

　概要を見る

© 2017 Elsevier B.V. Sloshing is the movement of liquid in a container induced by an external force. The phenomenon has been extensively studied at the macroscopic scale because of the importance of liquid control in tanks. Sloshing at the microliter scale should be explored for microdroplets in Lab-on-a-chip applications. We therefore verified the sloshing characteristics of droplets in microliter-sized wells. A water-in-oil droplet in the well was vibrated horizontally at between 20 and 100 Hz. Circular and elliptic wells between 2 and 5 mm sizes were applied for the well geometry. The surface chemistry of the well was additionally changed by using amphiphobic coatings to examine the effect of the interfacial tension between the well surface and the liquid, because we considered it a dominant factor at the microliter scale. Decreasing the well diameter caused the natural frequency to increase and the sloshing to suppress. This agreed with Housner's equation, which is conventionally used for macroscopic scale. The experiments also revealed that decreasing the interfacial tension caused the natural frequency to increase and resulted in drastic suppression of the sloshing, which was characterized by Bond number, similarly with the cases under microgravity. We experimentally verified that at the microliter scale, the interfacial tension is dominant to control the sloshing phenomenon.

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Three-axis scanning force sensor with liquid metal electrodes

T. Nakadegawa, H. Ishizuka, N. Miki

Sensors and Actuators A: Physical （Elsevier）  264   260 - 267 2017年09月

研究論文（学術雑誌）, 共著, 査読有り

Fatigue assessment by electroencephalogram measured with candle-like dry microneedle electrodes

Y. Kudo, M. Arai, N. Miki

Micro Nano Letters 12 （ 8 ） 545 - 549 2017年08月

研究論文（学術雑誌）, 共著, 査読有り

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Fatigue evaluation by detecting blink behavior using eyeglass-shaped optical sensor system

R. Horiuchi, T. Ogasawara, N. Miki

Micro Nano Letters 12 （ 8 ） 554 - 559 2017年05月

研究論文（学術雑誌）, 共著

Serial DNA relay in DNA logic gates by electrical fusion and mechanical splitting of droplets

H. Yasuga, K. Inoue, R. Kawano, M. Takinoue, T. Osaki, K. Kamiya, N. Miki, S. Takeuchi

PLOS ONE 12 （ 7 ） e0180876 2017年07月

研究論文（学術雑誌）, 共著, 査読有り

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Hollow hydrogel microfiber encapsulating microorganisms for mass-cultivation in open systems

K. Higashi, M. Ogawa, K. Fujimoto, H. Onoe, N. Miki

Micromachines （MDPI）  8 （ 6 ） 176 2017年06月

研究論文（学術雑誌）, 共著, 査読有り

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Wearable line of sight detection system for inverting glasses

T. Ogasawara, R. Horiuchi, Y. Tanaka, N. Miki

Micro Nano Letters 12 （ 8 ） 560 - 563 2017年08月

研究論文（学術雑誌）, 共著

Three-axis Capacitive Force Sensor with Liquid Metal Electrodes for Endoscopic Palpation

T. Nagatomo and N. Miki

Micro Nano Letters 12 （ 8 ） 564 - 568 2017年08月

研究論文（学術雑誌）, 共著, 査読有り

Encoding and presentation of surface textures using a mechanotactile display

Makoto Kawazoe, Yumi Kosemura, Norihisa Miki

Sensors and Actuators A: Physical （Elsevier）  261   30 - 39 2017年07月

研究論文（学術雑誌）, 共著, 査読有り

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Development of a tactile display with 5 mm resolution using an array of magnetorheological fluid

Hiroki Ishizuka & Norihisa Miki

Japanese Journal of Applied Physics 56 （ 6S1 ） 06GN19 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Micro-rube mass production system with microfluidic device for microbial culture

K. Fujimoto, K. Higashi, H. Onoe, N. Miki

Japanese Journal of Applied Physics 56 （ 6S1 ） 06GM02 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Evaluation of biofouling in stainless microfluidic channels for implantable multi-layered dialysis device

T. Ota, N. To, Y. Kanno, N. Miki

Japanese Journal of Applied Physics 56 （ 6S1 ） 06GN10 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Electrotactile display composed of two-dimensionally and densely distributed microneedle electrodes

M. Tezuka, K. Ishimaru, N. Miki

Sensors and Actuators A. Physical （Elesevier）  258   32 - 38 2017年02月

研究論文（学術雑誌）, 共著, 査読有り

Development of a polymer based fully flexible electrode tip for neuronal micro-stimulation applications

Romain DAVID, Norihisa MIKI

Japanese Journal of Applied Physics 56 （ 6S1 ） 06GN02 2017年05月

研究論文（学術雑誌）, 共著, 査読有り

Thermal and quantum phase slips in niobium-nitride nanowires based on suspended carbon nanotubes

Kohei Masuda, Satoshi Moriyama, Yoshifumi Morita, Katsuyoshi Komatsu, Tasuku Takagi, Takayuki Hashimoto, Norihisa Miki, Takasumi Tanabe, and Hideyuki Maki

Applied Physics Letters 108   222601 2016年05月

研究論文（学術雑誌）, 共著, 査読有り

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Polymer-based candle-like micro-needle electrodes for electroencephalogram measurement from the hairly part of the scalp

Miyako Arai, Yuta Kudo, Norihisa Miki

Japanese Journal of Applied Physics 55 （ 6S1 ） 06GP16 2016年05月

研究論文（学術雑誌）

Information transfer using wearable thin electro-tactile displays with micro-needle electrodes

Mayuko Tezuka, Norihide Kitamura, Norihisa Miki

Japanese Journal of Applied Physics 55 （ 6S1 ） 06GP15 2016年05月

研究論文（学術雑誌）, 共著

Surface properties that can be displayed by a MEMS-based mechanical tactile display

Yumi Kosemura, Shoichi Hasegawa, Norihisa Miki

Micro & Nano Letters 11 （ 5 ） 240 - 243 2016年05月

研究論文（学術雑誌）, 共著, 査読有り

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Logic gate operation by DNA translocation through biological nanopores

Hiroki Yasuga, Ryuji Kawano, Masahiro Takinoue, Yutaro Tsuji, Toshihisa Osaki, Koki Kamiya, Norihisa Miki, Shoji Takeuchi

PLOS ONE 11 （ 2 ） e0149667 2016年02月

研究論文（学術雑誌）, 共著, 査読有り

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Qualitative and quantitative estimation of comprehensive synaptic connectivity in short- and long-term cultured rat hippocampal neurons with new analytical methods inspired by Scatchard and Hill plots

Ryo Tanamoto, Yutaka Shindo, Mariko Niwano, Yoshinori Matsumoto, Norihisa Miki, Kohji Hotta, Kotaro Oka

Biochemical and Biophysical Research Communications （Science Direct）  471 （ 4 ） 486 - 491 2016年03月

研究論文（学術雑誌）, 共著, 査読有り

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Presentation of various tactile sensation using micro-needle-based electrotactile display

M. Tezuka, N. Kitamura, K. Tanaka, and N. Miki

PLOS ONE 11 （ 2 ） e0148410 2016年02月

研究論文（学術雑誌）, 共著, 査読有り

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Mental fatigue monitoring using a wearable transparent eye detection system

K. Sampei, M. Ogawa, C.C.C. Torres, M. Sato, and N. Miki

Micromachines （mdpi）  7 （ 2 ） 20 2016年01月

研究論文（学術雑誌）, 共著, 査読有り

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Fabrication of hemispherical liquid encapsulated structures based on droplet molding

Hiroki Ishizuka, Norihisa Miki

Journal of Micromechanics and Microengineering （IOP Publishing）  25   125010 2015年10月

研究論文（学術雑誌）, 共著, 査読有り

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Electrical stimulation of cultured neurons using a simply patterned indium-tin-oxide (ITO) glass electrode

Ryo Tanamoto, Yutaka Shindo, Norihisa Miki, Yoshinori Matsumoto, Kohji Hotta, Kotaro Oka

Journal of Neuroscience Methods 253   272 - 278 2015年09月

研究論文（学術雑誌）, 共著, 査読有り

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Logarithmic concentration gradients regulated by the width of channels for rapid determination of half maximal inhibitory concentration (IC50) of transporter proteins

Yuta Abe, Hirotaka Sasaki, Koki Kamiya, Toshihisa Osaki, Ryuji Kawano, Norihisa Miki, and Shoji Takeuchi

Analyst （RSCPublishing）  140   5557 - 5562 2015年

研究論文（学術雑誌）, 共著, 査読有り

Water-Permeable Dialysis Membranes for Multi-Layered Micro Dialysis System

Naoya To, Ippei Sanada, Hikaru Ito, Gunawan Setia, Shinya Morita, Yoshihiko Kanno, Norihisa Miki

Frontiers in Bioengineering and Biotechnology 3   70 2015年06月

研究論文（学術雑誌）, 共著, 査読有り

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Electroencephalogram measurement using polymer-based dry micro-needle electrode

Miyako Arai, Yuya Nishinaka, and Norihisa Miki

Japanese Journal of Applied Physics 54   06FP14 2015年05月

研究論文（学術雑誌）, 共著

Crosstalk analysis, its effects and reduction techniques among photovoltaic devices used as transparent optical sensors for a wearable line-of-sight detection system

Carlos Cesar Cortes Torres, Kota Sampei, Miho Ogawa, Masataka Ozawa, Norihisa Miki

Japanese Journal of Applied Physics 54   06FP16 2015年06月

研究論文（学術雑誌）, 共著

Electrotactile display using microfabricated micro-needle array

Kitamura, Norihide; Chim, Julien; Miki, Norihisa

Journal of Micromechanics and Microengineering （IOP）  25   025016 2015年01月

研究論文（学術雑誌）, 共著

• Access to Document (DOI)

Solute diffusion through fibrotic tissue formed around protective cage system for implantable devices

G.S. Prihandana, H. Ito, K. Tanimura, H. Yagi, Y. Hori, O. Soykan, R. Sudo, and N. Miki

Journal of Biomedical Materials Research Part B: Applied Biomaterials 103 （ 6 ） 1180 - 1187 2015年08月

研究論文（学術雑誌）, 共著, 査読有り

• Access to Document (DOI)

Application of powder suspended in dielectric fluid for fine finish micro-EDM of Inconel 718

G.S. Prihandana, T. Sriani, M. Mahardika, M. Hamdi, N. Miki, Y.S. Wong, K. Mitsui

International Journal of Advanced Manufacturing Technology （Springer）  75   599 - 613 2014年07月

研究論文（学術雑誌）, 共著, 査読有り

Tactile display for presenting stiffness distribution using magneto-rheological fluid

H. Ishizuka, N. Lorenzoni, and N. Miki

Mechanical Engineering Journal １ （ 4 ） FE0034 2014年08月

研究論文（学術雑誌）, 共著, 査読有り

A portable lipid bilayer system for environmental sensing with a transmembrane protein

R. Kawano, Y. Tsuji, K. Kamiya, T. Kodama, T. Osaki, N. Miki, and S. Takeuchi

PLOS ONE 9 （ 7 ） e102427 2014年07月

研究論文（学術雑誌）, 共著, 査読有り

A self-swimming microbial robot using microfabricated nanofibrous hydrogel

K. Higashi and N. Miki

Sensors and Actuators B: Chemical 202   301 - 306 2014年10月

研究論文（学術雑誌）, 共著

Characterization of surfaces virtually created by MEMS tactile display

Y. Kosemura, H. Ishikawa, J. Watanabe, and N. Miki

Japanese Journal of Applied Physics 53   06JM11 2014年05月

研究論文（学術雑誌）, 共著, 査読有り

Wearable line-of-sight detection system using micro-fabricated transparent optical sensors on eyeglasses

Masataka Ozawa, Kota Sampei, Cortes Carlos, Miho Ogawa, Akira Oikawa, Norihisa Miki

Sensors and Actuators A: Physical 205   208-214 2014年01月

研究論文（学術雑誌）, 共著, 査読有り

Droplet split-and-contact method for high-throughput transmembrane electrical recording

Y. Tsuji, R. Kawano, T. Osaki, K. Kamiya, N. Miki, S. Takeuchi

Analytical Chemistry 85 （ 22 ） 10913-10919 2013年11月

研究論文（学術雑誌）, 単著, 査読有り

Permeability and blood compatibility of nanoporous parylene film-coated polyethersulfone membrane under long-term blood diffusion

Gunawan Setia Prihandana, Hikaru Ito, Yuya Nishinaka, Yoshihiko Kanno, Norihisa Miki

Journal of Applied Polymer Science 131 （ 6 ） 40024 2014年03月

研究論文（学術雑誌）, 共著, 査読有り

Study of workpiece vibration in powder-suspended dielectric fluid in micro-EDM processes

G.S. Prinahdana, M. Mahardika, H.A. Shukor, W.Y. San, N. Miki, K. Mitsui

International Journal of Precision Engineering and Manufacturing 14 （ 10 ） 1817 - 1822 2013年10月

研究論文（学術雑誌）, 共著, 査読有り

A peristaltic micropump using traveling waves on a polymer membrane

K. Nakahara, M. Yamamoto, Y. Okayama, K. Yoshimura, K. Fukagata, N. Miki

Journal of Micromechanics and Microengineering 23   085024 (7pp) 2013年07月

研究論文（学術雑誌）, 共著, 査読有り

Antithrombogenicity of Fluorinated Diamond-Like Carbon Films Coated Nano Porous Polyethersulfone (PES) Membrane

Gunawan S. Prihandana, Sanada Ippei, Hikaru Ito, Mayui Noborisaka, Yoshihiko Kanno, Tetsuya Suzuki and Norihisa Miki

Materials 6 （ 10 ） 4309-4323 2013年09月

研究論文（学術雑誌）, 共著, 査読有り

Micropatterning of Silica Nanoparticles by Electrospray Deposition through a Stencil Mask

Kazuhiko Higashi, Kazuhiro Uchida, Atsushi Hotta, Koichi Hishida, Norihisa Miki

Journal of Laboratory Automation 19 （ 1 ） 75 - 81 2013年02月

研究論文（学術雑誌）, 共著, 査読有り

Automated Parallel Recordings of Topologically Identified Single Ion Channels

Ryuji Kawano, Yutaro Tsuji, Koji Sato, Toshihisa Osaki, Koki Kamiya, Minako Hirano, Toru Ide, Norihisa Miki, Shoji Takeuchi

Scientific Resports 3   1995 2013年06月

研究論文（学術雑誌）, 共著, 査読有り

Round-Tip Dielectrophoresis-Based Tweezers for Single Micro-Object Manipulation

Taiga Kodama,Toshihisa Osaki, Ryuji Kawano, Koki Kamiya, Norihisa Miki, and Shoji Takeuchi

Biosensors and Bioelectronics 47   206-211 2013年03月

研究論文（学術雑誌）, 共著, 査読有り

A microfluidic device for bacteria immobilization in a microporous carrier by dielectrophoresis

Kano, Tomonori; Inaba, Tomomi; Ye, Gu; Miki, Norihisa

Journal of Micro-Nano Mechatronics 7 （ 1-3 ） 61-68 2012年12月

研究論文（学術雑誌）, 共著, 査読有り

Droplet based lipid bilayer system integrated with microfluidic channels for solution exchange

Y. Tsuji, R. Kawano, T. Osaki, K. Kamiya, N. Miki and S. Takeuchi

Lab on a Chip 13 （ 8 ） 1476-1481 2013年

研究論文（学術雑誌）, 共著, 査読有り

Effects of Micromachining Processes on Electro-Osmotic Flow Mobility of Glass Surfaces

Yosuke Koga, Ryoko Kuriyama, Yohei Sato, Koichi Hishida, Norihisa Miki

Micromachines 4 （ 1 ） 67-79 2013年03月

研究論文（学術雑誌）, 共著, 査読有り

Microfabrication of Super Absorbent Polymer Structures by Nanoimprinting and Post Swelling Process

Tomomi Inaba, Tomonori Kano and Norihisa Miki

Japanese Journal of Applied Physics 52   06GL11 2013年06月

研究論文（学術雑誌）, 共著, 査読有り

Fabrication of Polymer Micro-needle Electrodes Coated with Nanoporous Parylene

Nishinaka Yuya, Rina JunZen, Gunawan Setia Prihandana, Norihisa Miki

Japanese Journal of Applied Physics 52 （ 6 ） 06GL10 2013年06月

研究論文（学術雑誌）, 共著, 査読有り

Manufacture of glass nanoparticles by electrospraying

K. Uchida, A. Hotta, K, Hishida, and N. Miki

Journal of Micromechanics and Microengineering 23   025023 (9pp) 2013年01月

研究論文（学術雑誌）, 共著, 査読有り

Flow type microbial chip for screening of a single bacterium

Tomonori Kano, Tomomi Inaba, Kazuhiko Higashi, Norihisa Miki

Micro Nano Letters 7 （ 12 ） 1213-1216 2012年12月

研究論文（学術雑誌）, 共著, 査読有り

Flexible Capacitive Sensor Encapsulating Liquids as Dielectric with a Largely Deformable Polymer Membrane

Nurul Adni Ahmad Ridzuan, Shun Masuda, Yasunari Hotta, Yuhua Zhang, and Norihisa Miki

Micro Nano Letters 7 （ 12 ） 1193-1196 2012年12月

研究論文（学術雑誌）, 共著, 査読有り

Polyethersulfone (PES) Membrane Coated with Nanoporous Parylene for Ultrafiltration

G.S. Prihandana, H. Ito, Y. Nishinaka, Y. Kannno, N. Miki

Journal of Microelectromechanical Systems 21 （ 6 ） 1288-1290 2012年12月

研究論文（学術雑誌）, 共著, 査読有り

Studies on the solution parameters for the fabrication of thinner silicone fibers by electrospinning

A. Nakano, N. Miki, K. Hishida, A. Hotta

Physical Review E 86   011801 2012年07月

研究論文（学術雑誌）, 共著, 査読有り

Development of a nanotechnology-based dialysis device

Yoshihiko Kanno and Norihisa Miki

Contributions to Nephrology 177   177-183 2012年05月

研究論文（学術雑誌）, 共著, 査読有り

Microtechnology-based three-dimensional spheroid formation

H. Ota and N. Miki

Frontiers in Bioscience, Elite 5   37-48 2013年01月

研究論文（学術雑誌）, 共著, 査読有り

Demonstration of vibrational braille code display using large displacement micro-electo-mechanical system actuators

Junpei Watanabe, Hiroaki Ishikawa, Xavier Arouette, Yasuaki Matsumoto, Norihisa Miki

Japanese Journal of Applied Physics 51   06FL11 2012年

研究論文（学術雑誌）, 共著, 査読有り

Effect of Microscale Surface Geometry of Electrodes on Performance of Microbial Fuel Cells

Tomonori Kano, Eiichi Suito, Koichi Hishida, and Norihisa Miki

Japanese Journal of Applied Physics 51   06FK04 2012年

研究論文（学術雑誌）, 共著, 査読有り

A Flexible Capacitive Sensor with Encapsulated Liquids as Dielectric

Yasunari Hotta, Yuhua Zhang, Norihisa Miki

Micromachines （MDPI AG）  3 （ 1 ） 137-149 2012年03月

研究論文（学術雑誌）, 共著, 査読有り

接触法による膜たんぱく質のアレイ化

辻祐太郎, 川野竜司, 大崎寿久, 佐々木啓孝, 三木則尚, 竹内昌治

電気学会論文誌Ｅ 131 （ 12 ） 419-424 2011年

研究論文（学術雑誌）, 共著, 査読有り

Rapid formation of size-controlled three dimensional hetero-cell aggregates using micro-rotation flow for spheroid study

Hiroki Ota, Taiga Kodama and Norihisa Miki

Biomicrofluidics 5   034105 2011年09月

研究論文（学術雑誌）, 共著, 査読有り

Microfluidic experimental platform for producing size-controlled three-dimensional spheroids

H. Ota and N. Miki,

Sensors and Actuators A 169   266-273 2011年10月

研究論文（学術雑誌）, 共著, 査読有り

Microscale Patterning of Single Crystal Diamond by Thermochemical Reaction between Sidero-Metal and Diamond

Yuko Morofushi, Hajime Matsushita and Norihisa Miki

Precision Engineering 35 （ 3 ） 502-507 2011年07月

研究論文（学術雑誌）, 共著, 査読有り

Theoretical analysis of 3D emulsion droplet generation by a device using coaxial glass tubes

Ye Gu, Hiroyuki Kojima, and Norihisa Miki

Sensors and Actuators A: Physical 169   326-332 2011年10月

研究論文（学術雑誌）, 共著, 査読有り

Formation of Polymer Microneedle Arrays Using Soft Lithography

Yoshimichi Ami, Hiroto Tachikawa, Naoki Takano, Norihisa Miki

Journal of Micro/Nanolithography, MEMS, and MOEMS 10 （ 1 ） 011503 2011年03月

研究論文（学術雑誌）, 共著, 査読有り

透過型光センサアレイを用いたウェアラブル視線検出システム

及川啓，室貴之，三木則尚

日本ロボット学会誌 29 （ 4 ） 369-375 2011年05月

研究論文（学術雑誌）, 共著, 査読有り

An Optimal Design of Epidermal Ridges to the Tacile Sensor for Sensitivity Enhancement during Shear Force Detecton

Y. Zhang and N. Miki

電気学会Ｅ部門論文誌 131 （ 4 ） 141-147 2011年04月

研究論文（学術雑誌）, 共著, 査読有り

Liquid Phase Formation of Silver Nanoparticles on a Glass Substrate Regulated by Gold Nanoparticles

K. Hanada, K. Uchida, D. Citterio, and N. Miki

Sensors and Materials 2010年

研究論文（学術雑誌）, 共著, 査読有り

Characterization of a Bonding-in-Liquid Technique for Liquid Encapsulation into MEMS Devices

Y. Okayama, K. Nakahara, A. Xavier, T. Ninomiya, Y. Matsumoto, Y. Orimo, A. Hotta, M. Omiya, and N. Miki

Journal of Micromechanics and Microengineering 20   095018 (6pp) 2010年

研究論文（学術雑誌）, 共著, 査読有り

Parallel formation of three-dimensional spheroid using micro-rotational flow

Hiroki Ota and Norihisa Miki

Journal of Robotics and Mechatronics 22 （ 5 ） 587-293 2010年

研究論文（学術雑誌）, 共著, 査読有り

Sensitivity enhancement of a micro-scale biomimetic tactile sensor with epidermal ridges

Yuhua Zhang and Norihisa Miki

Journal of Micromechanics and Microengineering 20   085012 (7pp) 2010年07月

研究論文（学術雑誌）, 共著, 査読有り

刺入型水分量測定センサを用いた植物水ストレス変化の検出

片柳仁，三木則尚

電気学会論文誌E 130 （ 9 ）  2010年

研究論文（学術雑誌）, 共著, 査読有り

Effect of tension and curvature of skin on insertion characteristics of microneedle array

H. Tachikawa, N. Takano, K. Nishiyabu, N. miki and Y. Ami

Journal of Solid Mechanics and Materials Engineering 4 （ 3 ） 470-480 2010年

研究論文（学術雑誌）, 共著, 査読有り

Dynamic Characteristics of a Hydraulic Amplification Mechanism for Large Displacement Actuators Systems

Arouette, X.; Matsumoto, Y.; Ninomiya, T.; Okayama, Y.; Miki, N.

Sensors 10   2946-2956 2010年03月

研究論文（学術雑誌）, 共著, 査読有り

Three-dimensional spheroid-forming lab-on-a-chip using micro-rotational flow

Hiroki Ota, Ryosuke Yamamoto, Koji Deguchi, Yuta Tanaka, Yutaka Kazoe, Yohei Sato, Norihisa Miki

Sensors and Actuators B: Chemical 147 （ 1 ） 359-365 2010年05月

研究論文（学術雑誌）, 共著, 査読有り

Needle-Type in situ Water Content Sensor with Polyethersulfone Polymer Membrane

T. Iwashita, H. Katayanagi, and N. Miki

Sensors and Actuators B: Chemical 154   41-45 2011年05月

研究論文（学術雑誌）, 共著, 査読有り

Fluorescence Imaging Technique of Surface Electrostatic Potential Using Evanescent Wave Illumination

Y. Kazoe, S. Miyakawa, N. Miki, and Y. Sato

Applied Physics Letters 95 （ 23 ） 234104 2009年12月

研究論文（学術雑誌）, 共著, 査読有り

液滴の拡散混合を利用した流れ方向濃度グラジエント生成デバイスの開発

鵜澤　翔平,有賀　啓二,三木　則尚

電気学会E部門誌 130 （ 2 ） 44-52 2010年02月

研究論文（学術雑誌）, 共著, 査読有り

Photochemically induced increase in endothelial permeablity regulated by RhoA activation

Hiroki Ota, Mimiko Matsumura, Norihisa Miki and Haruyuki Minamitami

Photochemical & Photobiological Sciences 8 （ 10 ） 1401-1407 2009年

研究論文（学術雑誌）, 共著, 査読有り

MEMS-based hydraulic displacement amplification mechanism with completely encapsulated liquid

T. Ninomiya, Y. Okayama, Y. Matsumoto, X. Arouette, K. Osawa and N. Miki

Sensors and Actuators A: Physical 166   277-282 2011年03月

研究論文（学術雑誌）, 共著, 査読有り

A multilayered microfilter using PES nano porous membrane applicable as the dialyzer of a wearable artificial kidney

Gu Ye and Norihisa Miki

Journal of Micromechanics and Microengineering 19   065031 (8pp) 2009年06月

研究論文（学術雑誌）, 共著, 査読有り

Site-Selective Deposition of Silver Nanoparticles Using Modified Silver Mirror Reaction and Surface Modification by Self-Assembled Monolayer

K. Hanada, K. Kurooka and N. Miki

Sensors and Materials 21 （ 3 ） 129-139 2009年

研究論文（学術雑誌）, 単著, 査読有り

　概要を見る

We developed a set of processes for depositing silver nanoparticles on a glass substrate that involves using a modified silver mirror reaction, whereby dispersants are added to a conventional silver mirror solution. The whole set of processes was completed in 15 minutes in a non-vacuum environment except the cleaning processes with oxygen plasma at 20 Pa and at a low cost. The processes can be applied to the site-selective deposition of silver nanoparticles by modifying the surface characteristics of glass substrates using a self-assembled monolayer (SAM). We used a microcontact printing method that incorporated a non-photolithographic top-down process to pattern a SAM. The proposed processes are readily applicable to promising applications of metal nanoparticles, such as ultrasensitive sensors and catalysts.

WATER-VAPOR PERMEABILITY CONTROL OF PDMS BY THE DISPERSION OF COLLAGEN POWDER

Y. Zhang, M. Ishida, Y. Kazoe, Y. Sato and N. Miki

TEEE：IEEJ Transactions on Electrical and Electronic Engineering 4 （ 2 ）  2009年03月

研究論文（学術雑誌）, 単著, 査読有り

　概要を見る

Polydimethylsiloxane (PDMS) has been widely used as a material for µTAS devices due to the superior nature of its manufacturability and chemical resistance, etc. PDMS is known to allow the permeation of gas and water-vapor. This characteristic was applied to ensure an efficient oxygen supply to cells cultivated in micro chambers and power-free sample injection into micro fluidic devices. Some applications, such as long-term experiments with aqueous samples, however, prefer to avert the permeation of water-vapor through PDMS. This paper reports on a new method to control the water-vapor permeability of PDMS by dispersing collagen powder (collagen/PDMS polymer). Firstly, we evaluated the manufacturability and material strength of the collagen/PDMS polymer to see whether the polymer could be employed as a material for µTAS devices. Subsequently, we designed and fabricated micro-fluidic devices to directly measure the amount of water-vapor permeating through a PDMS or collagen/PDMS membrane and evaluated the effect of the dispersed collagen. The use of the dispersed collagen powder successfully reduced the water-vapor permeability of PDMS by 54%.

Gastric-Fluid-Utilizing Micro Battery for Micro Medical Devices

Hikaru Jimbo and Norihisa Miki

Sensers and Actuators B: Chemical 134 （ 1 ） 219-224 2008年08月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

A variety of micro medical devices have been developed to provide more advanced and less invasive medical treatment. An effective power supply is crucial to the operation of these devices. Currently, two types of power supply are used: small batteries or radio power transmission. However, the former limit the operating time of the devices, while radio power transmission affects other medical devices due to the electromagnetic waves. In this paper, we report on a gastric-fluid-utilizing micro battery (GMB) that utilizes the gastric fluid in the stomach as an electrolyte. The GMB is designed to be used in the stomach and to generate electricity based on the principle of the voltaic cell. It consists only of biocompatible materials, including the electrodes, porous ceramic filter, and polydimethylsiloxane casing. Platinum deposited on a thin glass plate and a zinc plate work as positive and negative electrodes, respectively. Though zinc dissolves during the generation of electricity, it is an essential trace metal for humans and, given the small amount released, is not toxic. The porous ceramic filter placed between the electrodes filters out any foreign materials in the stomach fluid and holds the gastric fluid by capillary attraction. In experiments, GMB successfully generated 1.0 mW (0.42 V, 2.41 mA) with a 200-Ω external load. It generated a stable output voltage of 0.6 V for more than 39 minutes with a 5-kΩ external load. We demonstrated the feasibility of the GMB for medical applications by successfully supplying power to a telemetric system and a tiny DC motor that is commercially available.

Wearable Pupil Position Detection System Utilizing Dye-Sensitized Photovoltaic Devices

T. Shigeoka, T. Muro, T. Ninomiya, and N. Miki

Sensors and Actuators A 145-146   103-108 2008年

研究論文（学術雑誌）, 単著, 査読有り

　概要を見る

Detection of the line-of-sight (LOS) has a variety of applications, such as communication tools for elderly or disabled people, assisting drivers,
and effective location of traffic signs. To realize such promising applications, there is strong demand for an LOS detection system that does not
restrict users’ activities and inflicts no mental stress. The LOS can be obtained by combining the directions of the face and eyes, respectively,
where the detection of location and motion of the pupils is a critical technology. In this paper, we propose a novel wearable pupil position detection
system, featuring minimum disturbance to users, both physically and mentally, via the use of dye-sensitized photovoltaic devices. These latter are
transparent and generate voltage according to the incident light intensity. Arraying the devices on wearable eyeglasses, this system detects the
difference in the reflection light from the pupil and the white of the eye and hence determines the position of the pupil. It is wearable as an eyeglass,
meaning it does not disturb users’ activities or eyesight. More importantly, it involves minimal physical and psychological stress. We fabricated
the photovoltaic device and demonstrated their feasibility to determine the location of the pupil.We found it possible to meet the required reaction
time of 100 ms by reducing the size of the device and to improve the accuracy of pupil location detection by arraying the devices.

A microfilter utilizing a polyethersulfone porous membrane with nanopores

Ye Gu and Norihisa Miki

Journal of Micromechanics and Microengineering 17   2308-2315 2007年10月

研究論文（学術雑誌）, 共著

　概要を見る

We present a novel microfilter system used for solutes selective separation by molecular sizes of 1~2nm. The microfilter system consists two layers of micro chambers made of PDMS and one piece of porous membrane made of polyethersulfone (PES) by wet phase immersion method. The PES membrane at the centre of the two micro chambers acts as a barrier of molecules larger than its pores. A novel method of bonding the PES membrane to PDMS surface was developed in the device fabrication. Diffusion in the microfilter was derived theoretically and applied in the filtering evaluation. Filtering capacity of this microfilter for molecules with molecular sizes varying from 0.3nm to 8.4nm was evaluated using solution samples of sodium chloride (NaCl) and Fluorescein Isothiocyanate (FITC) Dextrans with molecular weights of 4k, 20k and 70k. The filtering experiments indicated that the optimal membrane used for the device was P2S2 (Table 1). This microfilter system with the optimal PES membrane was believed to be capable for the selective separation at a molecular size barrier of 1~2nm and have a potential for the use in portable hemodialysis systems.

Non-photolithographic Manufacturing Processes for Micro-channels Functioned by Micro-contact-printed

Saigusa H, Suga Y, Miki N

IEEJ Transactions on Sensors and Micromachines 126-E （ 11 ） 603-606 2006年11月

研究論文（学術雑誌）, 単著, 査読有り

　概要を見る

微小量のサンプルを効率的に反応させるためには、サンプルの微小液滴をいかにハンドリングするかがキーとなる。本論文では微小液滴を、マイクロ流路表面の表面エネルギ制御により、パッシブに位置決め、移動させる方法を論じている。特に表面エネルギの制御をおこなう、自己組織単分子膜（SAM）のマイクロコンタクトプリントによる局所的転写技術を開発した。

Wafer Bonding Techniques for MEMS

N. Miki

SENSOR LETTERS （American Scientific Publishers）  3 （ 4 ） 263-273 2005年12月

研究論文（学術雑誌）, 単著, 査読有り,  ISSN  1546-198X

　概要を見る

ウエハボンディング技術は，MEMSにおいてパッケージングや3次元構造の製作において高く期待されており，一部では実用化が始まっている．本論文は，2004年までのウエハボンディング技術に関する研究をまとめた総説である．特に本論文では，ウエハボンディング技術を、直接接合、陽極接合、接着層を用いた接合、および表面活性接合の４つに分類し、それぞれについて解説した。

Effect of nanoscale surface roughness on the bonding energy of direct-bonded silicon wafers

MIKI N and Spearing SM

Journal of Applied Physics （AMER INST PHYSICS）  94 （ 10 ） 6800-6806 2003年11月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0021-8979

　概要を見る

シリコンウエハ接合の性能を決定する要因の一つに，ナノスケールの表面粗さがある．本論文では，表面粗さの評価パラメータとして，表面の一番高い点からある深さまでに含まれる面積を表すBearing Ratioを導入した．適切な深さを選択すると，Bearing Ratioはウエハ接合における両ウエハの接触面積を表す．ウエハ接合の性能は接合エネルギにより定量化され，これは接触面積に比例すると考えられる．薬品により任意の表面粗さをもつウエハを製作し，これらの接合実験によりBearing Ratioと接合エネルギが比例することを示し，ナノスケール表面粗さとウエハ接合の性能を初めて定量的に関連付けた．

Enhancement of rotordynamic performance of high-speed micro-rotors for power MEMS applications by precision deep reactive ion etching

Miki N, Teo CJ, Ho LC, Zhang X

SENSORS AND ACTUATORS A-PHYSICAL （ELSEVIER SCIENCE SA）  104 （ 3 ） 263-267 2003年05月

研究論文（学術雑誌）, 単著, 査読有り,  ISSN  0924-4247

　概要を見る

高性能Power MEMSデバイスの実現には，微小ロータの高速回転が不可欠である．ロータの回転性能を決定する要因の一つは，ロータのインバランスである．本論文において，ロータのインバランスがDeep Reactive Ion Etchingによる製作プロセスに依存していることを実験から証明した．さらにDRIEプロセスを最適化することにより，ロータのインバランスを軽減し，回転性能が向上することを示した．

Soft-magnetic rotational microwings in an alternating magnetic field applicable to microflight mechanisms

Miki N, Shimoyama I

JOURNAL OF MICROELECTROMECHANICAL SYSTEMS （IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC）  12 （ 2 ） 221-227 2003年04月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  1057-7157

　概要を見る

微小機構の飛行には，外部場からのエネルギ供給が有効であり，外部交流磁場により回転する磁性体回転翼はその条件を満たす．磁性体材料としてMEMS製作技術により成膜が容易，かつ姿勢制御にも利用可能な軟磁性体が優れている．回転中の磁性体翼のダイナミクスを実験，計算を通じて解析した．また微小回転翼の飛行特性を評価し，微小飛行機構への応用可能性を示した．

Multi-stack silicon-direct wafer bonding for 3D MEMS manufacturing

Miki N, Zhang X, Khanna R, Ayon AA, Ward D, Spearing SM

SENSORS AND ACTUATORS A-PHYSICAL （ELSEVIER SCIENCE SA）  103 （ 1-2 ） 194-201 2003年01月

研究論文（学術雑誌）, 単著, 査読有り,  ISSN  0924-4247

　概要を見る

シリコンウエハの直接接合プロセスは，強い接合力，および接着剤が必要ないことから，3次元構造をもつMEMSデバイス，特に　　Power MEMS デバイスなど高温，高圧下で使用されるMEMSデバイスの製作に有効である．本論文では，特に複数枚のシリコンウエハの直接接合によるMEMSデバイスの製作プロセスに付随する問題点，およびその解決方法を示した．

Preliminary development of a hydrocarbon-fueled catalytic micro-combustor

Spadaccini CM, Zhang X, Cadou CP, Miki N, Waitz IA

SENSORS AND ACTUATORS A-PHYSICAL （ELSEVIER SCIENCE SA）  103 （ 1-2 ） 219-224 2003年01月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  0924-4247

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マイクロ燃焼システムにおいては，燃料のチャンバ内における滞在時間が短いことによる燃焼効率の低下が問題となる．本論文では，触媒を利用したマイクロ燃焼システムを提唱し，実験により有効性を示した．三木はこの論文において，シリコンベースのマイクロ燃焼システムの開発に携わった．

Dynamics of a microflight mechanism with magnetic rotational wings in an alternating magnetic field

Miki N, Shimoyama I

JOURNAL OF MICROELECTROMECHANICAL SYSTEMS （IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC）  11 （ 5 ） 584-591 2002年10月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  1057-7157

　概要を見る

微小機構の安定した飛行には，姿勢制御が最も重要となる．本論文は，微小機構のボディ部分に形状磁気異方性をもつ磁性体を成膜し，交流磁場による磁気異方性トルクを利用した姿勢制御を提唱している．交流磁場は回転翼の駆動にも使用される．MEMS製作技術を用いて，微小飛行機構を製作し，交流磁場中において安定した飛行を実現した．また高速度カメラにより飛行を観察し，微小機構の飛行ダイナミクスを解析した．交流磁場により，同時に回転翼の駆動と姿勢制御をおこなうことにより，微小機構の簡素化，軽量化が可能となり，飛行が実現されたと結論した．

交流磁場中で回転するマイクロ磁性体回転翼

三木 則尚下山勲

日本電気学会，センサ・マイクロマシン準部門誌 121-E （ 4 ） 221-229 2001年

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

マイクロロボット移動用の回転翼に使用される磁性体は軟磁性体であり，回転中に磁化の大きさ，方向ともに変化する．本論文において，回転中の磁化および磁気トルクの変化を，計算および数ミリサイズのラージスケール磁性体翼による実験から解析した．磁性体の磁気特性とともに，形状磁気異方性が重要な役割を担っていることを明らかにした．また翼長0.9ミリメートルの磁性体回転翼をMEMS (Microelectromechanical Systems) 製作技術を用いて実現した．

Study on micro-flying robots

Miki N, Shimoyama I

ADVANCED ROBOTICS 13 （ 3 ） 245-246 1999年

研究論文（学術雑誌）, 共著,  ISSN  0169-1864

　概要を見る

マイクロロボットの移動には，地面との摩擦がなく，かつ３次元の移動が可能な飛行が有効である．本論文では，推力を得る方法として，交流磁場中で回転する磁性体回転翼を提唱し，数ミリサイズのラージサイズモデルによる実験を通じ，実現可能性を示した．

Effective Dissolution of a Gaseous Odorant in Liquid Using Gas Flow

Nakane T., Osaki T., Mimura H., Takamori S., Miki N., Takeuchi S.

Advanced Materials Technologies 2024年

　概要を見る

Olfactory receptors are known for their high specificity, sensitivity, and nanometer-sized sensing element, making them ideal for in situ odorant sensor applications. However, one of the major limitations of these sensors is the requirement for an aqueous environment to maintain their function, while most odorants are poorly soluble in water. To address this issue, a microfluidic device consisting of a gas-flow channel and a microwell is proposed that enables the effective dissolution of a gaseous odorant in an aqueous solution. Computational simulations are used to design the gas-flow channel and the well, and the performance of the odorant dissolution is verified using the fabricated device. This study considers that convection in water induced by the gas flow enhances the dissolution of a gaseous odorant. The feasibility of the device is demonstrated for on-site detection of a gaseous odorant. This approach facilitates the development of highly responsive and portable sensors utilizing olfactory receptors, offering a promising solution to the limitations of current odorant sensors.

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Bubble-Assisted Re-Formation of Individual Lipid Bilayers in Arrayed Device

Hashimoto I., Osaki T., Mimura H., Takamori S., Miki N., Takeuchi S.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2023-January   279 - 280 2023年

ISSN  10846999

　概要を見る

This paper describes a method capable of individual and selective re-formation of ruptured BLMs (bilayer lipid membranes) by using air bubbles in arrayed devices. BLMs play an important role in membrane protein studies, biosensor applications, and drug screening. In such applications, data throughput is a key issue, but BLMs are easily ruptured by physical/electrical disturbance, which makes it difficult to operate a large BLM array. In this work, we propose a bubble-assisted BLM re-formation method: An aqueous phase is divided by a small air bubble covered with a lipid monolayer. After the bubble departed, the divided aqueous phases are brought into contact with the lipid monolayer, resulting in formation of BLM. This method enables selective BLM re-formation in a multichannel device. To verify individual and selective BLM re-formation using this method, we developed a 4ch bubble-assisted device and demonstrated repetitive BLM re-formation.

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Hand-Driven Device for Preparation of Linearly Aligned Hydrogel Sheets

Kato A., Oda H., Takamori S., Mimura H., Osaki T., Miki N., Takeuchi S.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2023-January   313 - 314 2023年

ISSN  10846999

　概要を見る

In this paper, we present a three-layered device for preparation of heterologous core layers linearly aligned in a hydrogel sheet by a simple four-step process without using pumps. Recently, cell-based sensors have been developed for detection of odorant molecules owing to the sensitivity and selectivity of olfactory receptors to chemical substances. To detect various odorant molecules with these sensors, it is necessary to array multiple types of sensor cells expressing different olfactory receptors. We therefore propose a sheet-shaped sensor chip for a sensor-cell array. Previously, hydrogel sheets with heterogeneous cell patterns were produced using microfluidic devices with syringe pump systems, causing loss of both sample volumes and time for settings. Here, we develop a device that enables preparation of hydrogel sheets with a small amount of samples and with a single manual pipette.

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Gas-Flow Device for Effective Dissolution of Gas-Phase Odorants Utilized for Biohybrid Sensors

Nakane T., Osaki T., Mimura H., Takamori S., Miki N., Takeuchi S.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2023-January   293 - 294 2023年

ISSN  10846999

　概要を見る

This study describes a gas-flow device that enhances the solubility of gas-phase odorants into aqueous solution for cell-based sensors. Cell-based sensors using olfactory receptors have attracted attention because of their high sensitivity and selectivity. However, most of previous studies used liquid-phase odorants as a target sample due to their low solubility of gas-phase odorants even though the applications expect the gas-phase sensing. Therefore, we focus on gas-phase odorant detection using the gas-flow device. Here, we clarify the impact of the velocity of convection inside the solution to enhancement of the solubility, based on computational simulation. Moreover, we experimentally verify efficiency of odorant dissolution in two types of devices, compared with the negative control using a sample odorant.

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Cartridge Device Capable of Spontaneous Solution Exchange for Sensor Cell Production

Tanaka A., Takamori S., Mimura H., Osaki T., Miki N., Takeuchi S.

IEEE Symposium on Mass Storage Systems and Technologies （IEEE Symposium on Mass Storage Systems and Technologies）  2022-January   166 - 167 2022年

ISSN  21601968

　概要を見る

This paper reports a cartridge-type device to produce sensor cells with spontaneous solution exchange. Our group has developed a cell-based odorant sensor expressed olfactory receptors. These sensor cells presented excellent sensitivity and specificity, which would be useful for a wide range of sensor applications. However, production of such sensor cells requires multiple times of aseptic solution exchanges. In this work, we develop a cartridge-type cell culture device that utilizes capillary force for spontaneous solution exchange without pumps or tubes. When the cartridge is set to the exchange stage, the specified volume of solution is exchanged immediately. We experimentally examine the solution exchange, and demonstrate the response of a sensor cell to a chemical stimulus in the exchanged solution. We consider that the device would be useful to produce multiple types of sensor cells.

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Inverse problems in tactile displays

Miki N., Ishizuka H.

Proceedings of the International Display Workshops （Proceedings of the International Display Workshops）  27   929 - 930 2021年12月

ISSN  18832490

　概要を見る

Tactile displays, which present virtual surfaces and tactile information to the users, can potentially augment quality and quantity of information in human-computer interaction. In this presentation, we discuss how we solve the inverse problems of the tactile displays, i.e., how to derive the control parameters of the displays when the target tactile sensations are given, in which we propose the microfabricated tactile samples to deduce quantitative correlation between the surface properties and tactile perception.

Electropolishing parametric optimization of surface quality for the fabrication of a titanium microchannel using the taguchi method

Mahardika M., Setyawan M.A., Sriani T., Miki N., Prihandana G.S.

Machines （Machines）  9 （ 12 ）  2021年12月

　概要を見る

Titanium is widely used in biomedical components. As a promising advanced manufacturing process, electropolishing (EP) has advantages in polishing the machined surfaces of material that is hard and difficult to cut. This paper presents the fabrication of a titanium microchannel using the EP process. The Taguchi method was adopted to determine the optimal process parameters by which to obtain high surface quality using an L9 orthogonal array. The Pareto analysis of variance was utilized to analyze the three machining process parameters: applied voltage, concentration of ethanol in an electrolyte solution, and machining gap. In vitro experiments were conducted to investigate the fouling effect of blood on the microchannel. The result shows that an applied voltage of 20 V, an ethanol concentration of 20 vol.%, and a machining gap of 10 mm are the optimum machining parameters by which to enhance the surface quality of a titanium microchannel. Under the optimized machining parameters, the surface quality improved from 1.46 to 0.22 µm. Moreover, the adhesion of blood on the surface during the fouling experiment was significantly decreased, thus confirming the effectiveness of the proposed method.

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Design of microfluidic channels to prevent negative filtration in implantable hemofiltration devices

Kono R., Ota T., Ito T., Miyaoka Y., Ishibashi H., Kanno Y., Miki N.

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference （Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference）  2021   5051 - 5054 2021年11月

ISSN  1557170X

　概要を見る

In order to improve the quality of life of dialysis patients, our group have been developing an implantable hemofiltration device (IHFD) composed of multiple layers of dialysis membranes and microfluidic channels. To improve the hemodialysis performance of IHFD, preventing the negative filtration, which is caused by the oncotic pressure of blood, is mandatory. In this study, we fabricated IHFDs with five different microchannel designs and experimentally investigated the performance of each device in in vitro experiment. In addition, the successful IHFD was further evaluated by ex vivo experiments with a beagle dog. The experiments verified the effectiveness of the microchannel design, which will be used for the IHFD for in vivo experiments with pigs in the future.

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Micro Elastic Pouch Motors: Elastically Deformable and Miniaturized Soft Actuators Using Liquid-to-Gas Phase Change

Hirai S., Nagatomo T., Hiraki T., Ishizuka H., Kawahara Y., Miki N.

IEEE Robotics and Automation Letters （IEEE Robotics and Automation Letters）  6 （ 3 ） 5373 - 5380 2021年07月

　概要を見る

In the present study, we propose a largely deformable and miniaturized soft actuator that is made by an elastic rubber bladder (called a pouch) with a low-boiling-point liquid. When the temperature of the low-boiling-point liquid reaches 34 - C, the liquid inside the pouch evaporates, and the whole structure inflates. Thanks to the proposed fabrication method, we can make a miniaturized pouch of approximately 5 mm in diameter with a thin rubber membrane, and the pouch can inflate to a volume of 86 times or more compared to its initial volume and can generate approximately 20 N at maximum. We calculated the deformation model and developed the fabrication process through investigation of the thickness and the inflation volume of the pouch with respect to the process parameters. We then experimentally characterized the actuator with respect to the generated force, time response, and repeatability of the inflation. We believe that micro elastic pouch motors will contribute to soft robotic systems as a new component as a result of having unique characteristics, such as millimeter size and large deformability.

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Efficient Gas-to-Liquid Partition Using Gas-Flow Channels for Cell-Based Gaseous Odorant Detection

Nakane T., Osaki T., Mimura H., Miki N., Takeuchi S.

21st International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2021 （21st International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2021）     763 - 766 2021年06月

ISSN  9781665412674

　概要を見る

Cell-based sensors using olfactory receptors have attracted attention because of their high sensitivity and selectivity. A challenge is efficient partition of gaseous samples to the aqueous solution where the cell-based sensors reside. In this paper, we developed a device with a gas-flow channel, which allowed inflow of gaseous odorants over a well filled with aqueous solution. We considered that shear stress induced by the gas-flow at the gas-liquid interface initiate convectional mixing inside liquid and in turn, promotes partitioning of gaseous odorants into the solution. Solubility of a gaseous odorant was experimentally found to increase with the mixing strength. We further demonstrated efficient detection of a gaseous odorant using the sensor cells with the developed gas-flow device.

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Unsupervised Learning Enables Extraction of Tactile Information from Text Database

Nagatomo T., Hiraki T., Ishizuka H., Miki N.

IEEE Access （IEEE Access）  2021年

　概要を見る

In this work, we propose a new approach to tactile research using natural language processing of archival word corpus as the database. Tactile perception, or assessment of surfaces, is recognized as a language. Thus, by extracting touch-related words and sentences from a text corpus and learning their relationships, we can ultimately learn how humans perceive surfaces. We selected 6 adjectives and 42 onomatopoeias in Japanese as our tactile words. The adjectives represent physical properties, such as roughness and hardness, while onomatopoeias, such as “zara-zara” and “tsuru-tsuru,” are widely used to describe surfaces in Japanese and can correspond to both physical texture cognition and affective cognition. First, using natural language processing of word corpora, we successfully mapped the onomatopoeias with respect to the 6 adjectives, which matched well with the results based on an enquete-based survey. This verified the effectiveness of natural language processing for tactile research. In addition, principal component analysis revealed new tactile dimensions based on onomatopoeias, which we presumably assessaffective tactile dimensions. The proposed approach using natural language processing of archival text databases can provide a large number of datasets for tactile research and culminate in new findings and insights.

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RELIABLE RE-FORMATION OF A LIPID BILAYER USING A GEOMETRICALLY GUIDED AIR BUBBLE

Hashimoto I., Osaki T., Sugiura H., Mimura H., Miki N., Takeuchi S.

MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences （MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences）     351 - 352 2021年

　概要を見る

This paper reports successful re-formation of a lipid bilayer using an air bubble. Lipid bilayers have been used for membrane protein studies and biosensor applications. Droplet-contact-method is a simple and effective method to form the bilayers. A major challenge in using the bilayers originates from their vulnerability against physical and electrical disturbance, which leads the bilayer rapture and the droplet fusion. We previously proposed a concept to re-form a bilayer by introducing an air bubble to cut-and-split the merged droplet. In this work, we investigated the key parameters to guide the bubble and drastically enhanced the yield up to 97%.

Rapid and Resilient Detection of Toxin Pore Formation Using a Lipid Bilayer Array

Ito Y., Osaki T., Kamiya K., Yamada T., Miki N., Takeuchi S.

Small （Small）  16 （ 49 ）  2020年12月

ISSN  16136810

　概要を見る

An artificial cell membrane is applied to study the pore formation mechanisms of bacterial pore-forming toxins for therapeutic applications. Electrical monitoring of ionic current across the membrane provides information on the pore formation process of toxins at the single pore level, as well as the pore characteristics such as dimensions and ionic selectivity. However, the efficiency of pore formation detection largely depends on the encounter probability of toxin to the membrane and the fragility of the membrane. This study presents a bilayer lipid membrane array that parallelizes 4 or 16 sets of sensing elements composed of pairs of a membrane and a series electrical resistor. The series resistor prevents current overflow attributed to membrane rupture, and enables current monitoring of the parallelized membranes with a single detector. The array system shortens detection time of a pore-forming protein and improves temporal stability. The current signature represents the states of pore formation and rupture at respective membranes. The developed system will help in understanding the toxic activity of pore-forming toxins.

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Pipette Based Viscometer with Pressure Sensor Element

Cho S., Nguyen T.V., Miki N., Takahashi H.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2020-January   646 - 648 2020年01月

ISSN  9781728135809

　概要を見る

© 2020 IEEE. This paper reports a simple viscometer, whose principle utilizes the relationship between liquid viscosity and the suction speed in a tube. The proposed viscometer is composed of an air chamber and a glass tube. A steel ball is attached to the silicone membrane of the chamber and an electromagnetic magnet is used to provide the volume change. A MEMS pressure sensor element is attached to the chamber to measure its pressure change. When a step-response volume change is applied, the chamber pressure decreases so that the liquid sticking to the tube gradually ascends at a speed depending to the viscosity. Thus, the viscosity can be calculated by measuring the gradient of the pressure change. The proposed method can be applied to micropipettes so that viscosity is easily measured with a simple device.

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Bubble-Assisted in-Situ Re-Formation of Artificial Bilayer

Hashimoto I., Sugiura H., Osaki T., Yamada T., Mimura H., Miki N., Takeuchi S.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2020-January   1022 - 1023 2020年01月

ISSN  9781728135809

　概要を見る

© 2020 IEEE. This paper proposes a technique to reconstitute a lipid bilayer membrane by injecting an air bubble onto the raptured spot. Our group has been studying the artificial bilayer that can host membrane proteins and can be a fundamental to analyze their functions. The only drawback of the lipid bilayer formed at the interface of two water-in-oil droplets is its sustainability, namely, the bilayer often collapses and the droplets merges by the disturbance like self-exerted oscillation or sloshing. To overcome this issue, the newly proposed technique utilizes a bubble at approximately 4μL in volume. When the bubble is injected and retracted, the new artificial bilayer is reconstituted. The major advantage of this technique is the in-situ reconstitution of the bilayer during the electrical measurement of the membrane proteins. The proposed technique was successfully verified by confirming the emergence of nanopore membrane proteins.

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'Coat Pop': On-Substrate Two-Step Composition Patterning Method of Liquid Metal Alloys for Flexible Devices

David R., Miki N.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2020-January   946 - 948 2020年01月

ISSN  9781728135809

　概要を見る

© 2020 IEEE. We have developed a novel on-substrate composition patterning process of room-temperature liquid metal alloys via a simple two-step method: 'coat pop'. This work present for the first time the integration of a single or several noble metals (Au, Ag or Cu) on Ga-based liquid metal droplets on a single substrate, by using a spontaneous chemical reaction then simple mechanical compression, to form biphasic and liquid composition patterns. The controllable deposition of noble metals encapsulation patterns and formation of several interfaced conductive biphasic intermetallic alloys on a single substrate were successfully demonstrated.

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Towards realization of implantable dialysis system

Miki N.

Journal of Japan Institute of Electronics Packaging （Journal of Japan Institute of Electronics Packaging）  23 （ 5 ） 393 - 397 2020年

ISSN  13439677

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Synthesis of sub-micrometer biphasic Au-AuGa<inf>2</inf>/liquid metal frameworks

David R., Miki N.

Nanoscale （Nanoscale）  11 （ 44 ） 21419 - 21432 2019年11月

ISSN  20403364

　概要を見る

© 2019 The Royal Society of Chemistry. A novel biphasic sub-micrometer Au-AuGa2/liquid metal framework, consisting of solid nanoparticles encapsulating liquid metal (LM) droplets, is introduced. By utilizing oxide-free galvanic replacement of a Ga-alloy LM with alkaline KAuBr4, the controllable process of gold-based encapsulation of individual sub-micrometer LM droplets capped with polyvinylpyrrolidone, lysozyme or sodium alginate is demonstrated. The morphology, structure and composition of the encapsulated droplets are characterized in-depth via scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. For the first time, the existence of two kinetic regimes leading to the controllable synthesis of either intermetallic AuGa2 or Au nanoparticles to encapsulate LM droplets is highlighted via the study of the evolution of the pH of the reaction medium. The as-formed biphasic sub-micrometer Au-LM frameworks demonstrate moderate stability in an aqueous environment and formidable structural and chemical stability in ambient air at room temperature. The encapsulation process can be adapted to the micro-patterning of LM droplet surfaces to produce conductive Au-encapsulated LM droplets then sintered to recover LM lines, while the sub-micrometer Au-LM droplets can be reintegrated onto larger LM surfaces and volumes to create multi-metallic and multi-scale biphasic structures with controllable electrical properties. The adaptability of the encapsulation process to the macro-, micro- and nanoscale of liquid metal features with a wide range of surfactants could in principle allow its use in various systems and applications.

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EEG-Hat with Candle-like Microneedle Electrode

Kawana T., Yoshida Y., Kudo Y., Miki N.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS （Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS）     1111 - 1114 2019年07月

ISSN  9781538613115

　概要を見る

© 2019 IEEE. This paper reports the EEG-Hat, the hat-type EEG device with candle-like dry microneedle electrodes. Current wearable EEG devices have two major problems; 1) no adjustability to every participant and 2) no ability to measure EEG at hairy part. If these problems are solved, health care technologies in daily life will be developed drastically. The EEG-Hat potentially solves these problems. This device can adjust the electrodes to different size and shape of human head. This device has shutter-like structures to separate hair, so using this device, it is possible to measure EEG without separating hair by hand. First, we quantified the force to press the electrodes and the amount of separating hair. Then, the EEG-Hat fabricated based on the findings successfully measured EEG from 3 hairy parts without manual separation.

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Thermal Sensation Display with Controllable Thermal Conductivity

Hirai S., Miki N.

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII （2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII）     1659 - 1661 2019年06月

ISSN  9781728120072

　概要を見る

© 2019 IEEE. We demonstrate a thermal sensation display that can present various thermal sensation by varying the thermal conductivity of the display. Thermal sensation, i.e., cold/cool/warm/hot, is one of the major tactile sensations and needs to be further investigated to advanced VR/AR systems. Although many reports on the tactile displays present hot/cold surfaces by changing the surface temperature, the proposed display is the first one that can control thermal conductivity. The device contains liquid metal, whose contact to the top titanium plate determines the thermal conductivity of the device and thus, the thermal sensation presented to the users. This device can be a good platform for the study of thermal sensation.

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Quad Lipid Bilayer Module with 1-Gω Series Resistors Toward Quantitative Stochastic-Biosensors

Ito Y., Osaki T., Kamiya K., Yamada T., Miki N., Takeuchi S.

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII （2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII）     6 - 8 2019年06月

ISSN  9781728120072

　概要を見る

© 2019 IEEE. This work designs and demonstrates the lipid bilayer-based ultra-sensitive biosensor capable of short-time detection in a quantitative manner, which is achieved by connecting multiple sensor elements in parallel.Artificial cell membranes with functional membrane proteins can form sensitive/selective biosensors. But the sensors suffer lengthy detection time at low concentration of analytes because the sensing mechanism relies on stochastic phenomena.In this work, we connected independent membrane sensors in parallel, where the ionic current through the multiple membranes was monitored by a single detector. With this format, the detection time is shortened based on the number of the array and the sensing can be quantitative. We developed a quad sensor assembling four membranes in parallel, and examined detection time of a single membrane sensor, the quad sensor, and four parallel quad-sensors. 1-Gω resistor was installed in series with each membrane to avoid overload current caused by membrane rupture. The results showed significant improvement in the detection time and deviation by the parallelization, which promises quantitative monitoring with the stochastic sensor.

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A Flexible Tactile Sensor to Detect Stiffness Distribution Without Measuring Displacement

Nagatom T., Miki N.

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII （2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII）     551 - 553 2019年06月

ISSN  9781728120072

　概要を見る

© 2019 IEEE. In this study, we developed a flexible tactile sensor that scans the surface to detect the stiffness distribution. Note that the sensor does not need to know the displacement or strain of the target surface.Endoscopic palpation is a promising technology to detect tumors that have larger stiffness than normal tissues. The stiffness can be deduced by acquiring the load applied and the displacement, whereas the displacement or strain of the tissue is difficult to obtain given that endoscope has an arbitrary shape when in use and the tissue surface is not flat. In this study, we propose a new stiffness sensor composed of four strain gauges with different Young's modulus to detect the target without measuring the strain. The developed flexible sensor uses encapsulated liquid metal as the electrodes and can scan the surface.

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Electroencephalogram Measurement in Adapting Process to Inverse Vision

Onomoto T., Yoshida Y., Miki N.

2019 International Conference on Electronics Packaging, ICEP 2019 （2019 International Conference on Electronics Packaging, ICEP 2019）     134 - 137 2019年04月

ISSN  9784990218867

　概要を見る

© 2019 Japan Institute of Electronics Packaging. This paper describes investigation of the brain activity in an adapting process to inversion vision through electroencephalogram (EEG). In particular, we used Candle-like microneedle electrodes, which does not require any preparation for measuring high-quality EEG. Note that conventional wet electrodes require abrasion of stratum corneum and application of electrolyte paste as preparation for measurement of EEG and they give discomfort to subjects and take time for experimenters. In our previous study, the eye movement during the adapting process was measured and the progress of the process was successfully captured. In this study, we measured EEG during the pointing task under an inverse vision state to correlate the perceptual learning with EEG. We discovered that High β wave, Low γ wave and Mid γ wave had strong correlation with the process of adapting to inversed vision.

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Long-Term in vivo Experiment Protocol Using SD Rats

Ito T., Koya Y., Miki N.

2019 International Conference on Electronics Packaging, ICEP 2019 （2019 International Conference on Electronics Packaging, ICEP 2019）     144 - 148 2019年04月

ISSN  9784990218867

　概要を見る

© 2019 Japan Institute of Electronics Packaging. Our group has been developing implantable artificial dialysis system to decrease burden of chronic kidney disease patients. To evaluate the device, long-Term in vivo experiments are mandatory. However, we need to complete the detailed design of the devices prior to the long-Term tests, which range from the temporal change of the device performance to time to surgical procedures. To do so, we need to conduct mid-and long-Term in vivo experiments for multiple times to acquire sufficient information. It is useful to use small animals, such as rats, for in vivo experiment. However, there is no prior work that discusses mid-and long-Term coagulation ability control in small animals. In this study, we investigated the heparin administration to manage the coagulability. A simplified device was connected to SD rats under coagulability control and the blood coagulation in the device was characterized. And succeeded in blood clotting inhibition for 48 hours

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Tuneable Microparticle Filters

Iseri E., Kaya K., Di Dio G., Yasuga H., Miki N., Van Der Wijngaart W.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2019-January   290 - 291 2019年01月

ISSN  9781728116105

　概要を見る

© 2019 IEEE. We introduce microparticle filters with temperature tuneable size cut-off and surface energy. At room temperature, the filter cut-off is 164 \pm 23\ \mu \mathrm{m}, and the filter is water-absorbing/oil-repelling (hydrophilic). At 50 °C, the filter cut-off is 695\pm 31\ \mu \mathrm{m}, and the filter is oil-absorbing/water-repelling (hydrophobic).

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Stacking 2D Droplet Arrays for 3D Configurable Droplet Network

Yasuga H., Osaki T., Kamiya K., Iseri E., Van Der Wijngaart W., Takeuchi S., Miki N.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2019-January   387 - 388 2019年01月

ISSN  9781728116105

　概要を見る

© 2019 IEEE. Droplet interface bilayer (DIB) networks are expected to lead to tissue-like materials that can be designed from single droplets. Although various functions, such as sensors or computing, have been implemented into DIB networks, there remains a challenge in terms of configurability of constituent droplets in three-dimensional (3D). In this paper, we construct 3D DIB networks with defined droplet positions. We prepared 2D droplet arrays in paper-like substrates based on a method that we previously reported. Vertical stacking of the 2D arrays resulted in DIB formation between layers, i.e., a 3D DIB network.

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A Precise Sampling Strip with Microstructures

Kamiya H., Ota T., Yasuga H., Miki N.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS （Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS）  2018-July   3837 - 3840 2018年10月

ISSN  9781538636466

　概要を見る

© 2018 IEEE. This paper presents a precise sampling microstructure formed as a paper strip. We have been developing dialysis system that can be implanted into a human body as an artificial kidney. For the safe use of our artificial kidney, the patients' urine needs to be constantly monitored to detect the abnormal value of ion concentration essential for human life. We are conceiving the monitoring system based on sampling by a paper strip. In this study, we fabricated the strip consisting of slanted and interlocked micropillars for the sampling, known as synthetic microfluidic paper. The paper-like substrate can be fabricated with a well-controlled geometry and subsequently enables precise sampling. Through the conducted experiments, it was shown that synthetic microfluidic paper had better mechanical properties, showed more precision in sampling than paper filter as well as corresponding liquid holding capability to the paper filter. Our proposed paper-based sampling system is expected to lead to the development of minimally invasive ion monitoring system with quantitative sampling strip.

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Enfold-type connecting system of artificial blood vessels for micro implantable dialysis device

Watanabe A., Ota T., Kanno Y., Miki N.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS （Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS）  2018-July   5810 - 5813 2018年10月

ISSN  9781538636466

　概要を見る

© 2018 IEEE. This paper reports the connecting mechanism for the artificial blood vessels along with the recent development of the micro implantable dialysis device. Our group has been studying the micro implantable dialysis device, which will drastically improve the quality of life of dialysis patients. We expect to replace the device every couple of years, which will involve surgery. In order to simplify the surgery to reduce the load to the patients, we develop a connector for the artificial vessels, which allows the exchange of the device by low invasive surgery. The connector needs to be designed not to induce blood coagulation. We designed a connecting mechanism that enfolds the artificial vessels to allow blood to contact only to the surface of the artificial vessels. In order to verify effectiveness of the proposed connecting mechanism, we investigated the connector surfaces with SEM after blood circulation tests. Then, we evaluated blood coagulation capacity of the connecting system as well as the set of the connecting system and the micro dialysis device with respect to the activated partial thromboplastin time (APTT). No remarkable increase of blood coagulation at the connecting point was observed after 72 hours of blood circulation tests. Short-term experiments for 120 minutes to evaluate APTT showed a small decrease of APTT, which needs to be further investigated in a longer-term experiments.

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Automatic Planar Asymmetric Lipid Bilayer Membrane Formation toward Biological High-Throughput Assay

Gotanda M., Kamiya K., Osaki T., Fujii S., Misawa N., Miki N., Takeuchi S.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS （Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS）  2018-July   4496 - 4499 2018年10月

ISSN  9781538636466

　概要を見る

© 2018 IEEE. This paper describes automation of planar lipid bilayer formation by introducing a stepping motor to a microfluidic device. Planar lipid bilayers or lipid vesicles are useful to understand biological reactions and to investigate the interaction between lipids and proteins. Therefore, to acquire large amount of the information, high-throughput production of planar lipid bilayers or giant vesicles (GVs) is necessary. The droplet split-and-contact method, which enhances the efficiencies of both planar lipid bilayer formation and GV generation, needs to be automated for increasing the throughput. Previous droplet split-and-contact devices were manipulated manually; hence, the influence of manipulation on planar lipid bilayer formation was not evaluated quantitatively. First, to develop an automated system for generating asymmetric planar lipid bilayers, a stepping motor, which allows to control the angular speed of the rotor, is integrated into the droplet split- and-contact device (Fig. 1({b)). Next, we assessed planar lipid bilayer generation at various angular speeds and found the speed limit for bilayer formation. Finally, we generated asymmetric planar lipid bilayers that have different lipid composition on outer and inner leaflets using this automated device and confirmed the asymmetry of the planar lipid bilayers by generating GVs.

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Blood-Separating Device Without Energy Source for Implantable Medical Devices

Otsuki H., Ota T., Miki N.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS （Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS）  2018-July   4661 - 4664 2018年10月

ISSN  9781538636466

　概要を見る

© 2018 IEEE. Coagulation of blood inside the implanted medical device is quite a critical problem to limit the lifetime. In this paper, we propose a microfluidic blood separating device using curved and branched channels. It utilizes centrifugal force on curved flow and separates blood flow into blood cell rich and blood cell poor ones at the bifurcation. Though it cannot separate the plasma from blood cells completely, the blood with small concentrations of blood cells will have low coagulatibity and extend the lifetime of the implant medical device. The device does not require any external pumps or valves, i.e., the system does not need any power sources but the blood pressure. We conducted experiments with a titanium foil which contacted to human whole blood with different hematocrit values for 7 days. The device was experimentally characterized with respect to the channel design. The former experiments suggested that lower concentration of blood cells helps avoiding blood coagulations, and the latter showed that the separation by our device is mainly affected by the flow rate and channel curvature.

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Preparation-Free Measurement of Event-Related Potential in Oddball Tasks from Hairy Parts Using Candle-Like Dry Microneedle Electrodes

Yoshida Y., Kudo Y., Hoshino E., Minagawa Y., Miki N.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS （Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS）  2018-July   4685 - 4688 2018年10月

ISSN  9781538636466

　概要を見る

© 2018 IEEE. This paper reports successful measurement of even-related potential (ERP) using candle-like dry microneedle electrodes, which can acquire high-quality electroencephalogram (EEG) from hairy parts without any pretreatment. In our previous work, we successfully measured spontaneous EEG activity and its application to assess the stress state of the subjects. ERPs originate from electrophysiological response to stimulus and are one of the most important indices to capture the cognitive and sensory activities. In this work, using the candle-like dry microelectrodes, we demonstrate successful measurement of ERPs elicited by oddball tasks. Two oddball tasks using pure tone stimuli and speech stimuli were assigned to the subjects, where EEG was acquired from the parietal region (Cz in international 10-20 system). Note that no pretreatment, such as removal of hairs and abrasion of the scalp, was applied. As a result, P300 and mismatch negativity (MMN) were successfully measured in the both oddball tasks from the averaged EEG after the stimuli. Based on these results and given the attractive natures of the candle-like dry microneedle electrodes; they do not need any skin treatment and conductive gels and they can measure EEG from the hairy parts, the developed electrodes will accelerate cognitive neuroscience research using ERPs.

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Development of an automatic urine monitoring device using cross-selectivity sensing principle

Ioller B., Miki N.

2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018 （2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018）     324 - 327 2018年06月

ISSN  9784990218850

　概要を見る

© 2018 Japan Institute of Electronics Packaging. Despite today's race for IoT application dedicated to home care, and healthcare service, remote analysis of urine, one of the best bio-marker, remains quite challenging and can be improved. This paper demonstrates an automatic urine monitoring device using the capillarity effect inside a channel and cross-selectivity principle to create a modular and daily analysis solution. The developed device was tested on simulated urine and successfully determined its basic composition (ionic concentration and color). We finally proposed a realistic use-case for heatwave prevention in Japan by connecting our device with a ESP32 module to bring the daily result to a healthcare application.

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Reduction of parasitic capacitance of flexible tactile sensors

Nagatomo T., Miki N.

2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018 （2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018）     562 - 565 2018年06月

ISSN  9784990218850

　概要を見る

© 2018 Japan Institute of Electronics Packaging. In this study, we successfully reduced the parasitic capacitance of PDMS-based flexible tactile sensors by decreasing the dielectric constant of PDMS. UV exposure changes Si-CH3 bonds in PDMS to Si-O, which leads to the low dielectric constant. This simple but effective method can be readily applicable to improve signal-To-noise ratio of PDMS-based flexible sensors.

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Practical realization of enfold connecting system of artificial blood vessel for simplifying maintenance surgery evaluation of thrombus formation and blood coagulation capasity

Watanabe A., Ota T., Kanno Y., Miki N.

2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018 （2018 International Conference on Electronics Packaging and iMAPS All Asia Conference, ICEP-IAAC 2018）     141 - 144 2018年06月

ISSN  9784990218850

　概要を見る

© 2018 Japan Institute of Electronics Packaging. Evaluations for the enfold connecting system of system is developed to reduce and simplify the maintenance surgery of the artificial organ.The connector is designed not to contact the blood directly and the artificial blood vessel enfolds metal pipe in connector. Thanks to this design, the biocompatibility of the connector is comparable with an artificial vessel. We confirmed the blood coagulate protein which form a thrombus at the joint point of the connector with SEM. And we also measured a potential of blood coagulation by activated partial thromboplastin time (APTT). We didn't find the remarkable increase of blood coagulation on the connecting point for 72 hours. And APTT decreased a little in the experiment of a blood circulation system with the connector but we can't conclude that the connector causes a blood coagulation from results for 120 minutes. Additionally, we measured a potential of blood coagulation by APTT about the micro dialysis device which is developed in our group. We conducted the micro dialysis device experiments as with the same method of the connector experiments of APTT. We did not observe the remarkable disease of APTT for 120 minutes about the micro dialysis device as well. However, we found that the hemolysis was possible to be occurred in the micro dialysis device.

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Droplet microfluidics inside paper

Yasuga H., Guo W., Hansson J., Haraldsson T., Miki N., Van Der Wijngaart W.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2018-January   269 - 271 2018年04月

ISSN  9781538647820

　概要を見る

© 2018 IEEE. Here, we demonstrate, for the first time: the self-digitization, i.e. spontaneous formation, of microdroplets during the imbibition of paper; the on-demand merging of individual microdroplets in paper; and the on-demand ejection of individual microdroplets from the paper. Two technical novelties underlie these novel functions: the formation of free-standing synthetic microfluidic paper, i.e. a porous matrix of slanted and interconnected micropillars without bottom layer; and the hydrophobic surface modification of the paper. The ease of manipulation and the direct access to the microdroplets from the environment makes this an extremely versatile tool, with potential applications in liquid sample digitisation and microparticle generation.

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Triple-coaxial flow for continuous production of microtubes containing microbes for bioremediation

Fujimoto K., Higashi K., Onoe H., Miki N.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2018-January   1269 - 1271 2018年04月

ISSN  9781538647820

　概要を見る

© 2018 IEEE. This paper describes a microfluidic device to continuously produce a hydrogel microtube using triple-coaxial flow. In our prior work, double-coaxial flow was used to produce hydrogel microtubes, though continuous and mass production was a challenge. In this work, we also demonstrate bioremediation using the microtubes that encapsulate microbial suspension. The microenvironment created by the microtubes enabled efficient purification of aqueous sample solution and in addition, the microbes are maintained inside the microtube and are easily collected without contaminating the solution. The proposed technology can be applied to any types of microbes and can be of great benefit for various microbial processes.

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Liquid metal electrodes micro-array for electrical stimulation via direct contact

David R., Miki N.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2018-January   373 - 375 2018年04月

ISSN  9781538647820

　概要を見る

© 2018 IEEE. We have developed a novel liquid metal based electrodes micro-array for the electrical stimulation of biological tissues with a direct liquid metal - biological tissue contact surface. This work presents for the first time an effort to introduce Gallium based liquid metal components to the field of implantable electrical stimulation systems. The electrical performance and overall integrity of the liquid metal open micro-channel electrodes were fully characterized and analyzed in regard of the properties of the liquid metal used, the surrounding environment, and the stimulation signal. Stable direct contact stimulation electrodes down to a width of 50 μm were successfully produced and tested in-vitro.

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In vitro and in vivo tests of nanoporous membrane coated with biocompatible fluorine-doped diamond-like carbon for hemofiltration treatment

Ota T., Nakayama M., Kanno Y., Suzuki T., Miki N.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2018-January   412 - 414 2018年04月

ISSN  9781538647820

　概要を見る

© 2018 IEEE. In this report, we experimentally investigated the blood hemofiltration capacity of a nanoporous dialysis membrane (poly(ether sulfone), PES) whose surface was modified with fluorine-doped diamond-like carbon(f-DLC). Surface modification of the nanoporous membrane without clogging the nanopores is challenging. In vitro experiments revealed that the modified membrane successfully exhibited water permeability of one-tenth of the untreated. In vivo experiments with ultra-small hemofiltration devices composed of f-DLC PES membranes using SD rats were also conducted for the first time. The results proved that the f-DLC coated PES membrane can be used for hemofiltration, which will extend the lifetime of microfluidics-based implantable artificial kidney.

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Handheld nanopore-based biosensing device

Izawa Y., Osaki T., Kamiya K., Fujii S., Misawa N., Miki N., Takeuchi S.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) （Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)）  2018-January   2 - 5 2018年04月

ISSN  9781538647820

　概要を見る

© 2018 IEEE. This paper describes the development of a handheld device for long-term nanopore-based biosensing. Recently, membrane protein reconstituted in bilayer lipid membrane (BLM) has been applied for bio/chemical sensors because membrane protein intrinsically has a superior amplification mechanism. For mobile use of such devices, however, the bilayer requires mechanical robustness. Here, we propose a handheld BLM device aiming for a nanopore-based mobile sensor. BLM is formed at the tip of a glass capillary, which is contained in the solution trapped in a cup-like reservoir. This format achieved (i) formation of a sufficiently robust BLM for mobile use, (ii) solution exchange without rupturing BLM, and (iii) sustaining the small number of nanopores in the bilayer for accurate and long-term sensing. The handheld device successfully detected DNA translocations through the nanopores continuously for 75 minutes using 5 nanopores.

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Well-Controlled Cell-Trapping Systems for Investigating Heterogeneous Cell–Cell Interactions

Kamiya K., Abe Y., Inoue K., Osaki T., Kawano R., Miki N., Takeuchi S.

Advanced Healthcare Materials （Advanced Healthcare Materials）  7 （ 6 ）  2018年03月

ISSN  21922640

　概要を見る

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Microfluidic systems have been developed for patterning single cells to study cell–cell interactions. However, patterning multiple types of cells to understand heterogeneous cell–cell interactions remains difficult. Here, it is aimed to develop a cell-trapping device to assemble multiple types of cells in the well-controlled order and morphology. This device mainly comprises a parylene sheet for assembling cells and a microcomb for controlling the cell-trapping area. The cell-trapping area is controlled by moving the parylene sheet on an SU-8 microcomb using tweezers. Gentle downward flow is used as a driving force for the cell-trapping. The assembly of cells on a parylene sheet with round and line-shaped apertures is demonstrated. The cell–cell contacts of the trapped cells are then investigated by direct cell–cell transfer of calcein via connexin nanopores. Finally, using the device with a system for controlling the cell-trapping area, three different types of cells in the well-controlled order are assembled. The correct cell order rate obtained using the device is 27.9%, which is higher than that obtained without the sliding parylene system (0.74%). Furthermore, the occurrence of cell–cell contact between the three cell types assembled is verified. This cell-patterning device will be a useful tool for investigating heterogeneous cell–cell interactions.

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Three-dimensional rotation/translation microfluidic devices for sequential mixing

Tachibana T., Kamiya K., Osaki T., Misawa N., Fujii S., Miki N., Takeuchi S.

22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018 （22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018）  1   309 - 310 2018年

ISSN  9781510897571

　概要を見る

Copyright© (2018) by Chemical and Biological Microsystems Society.All rights reserved. This paper demonstrates a three-dimensional microfluidic device for sequence-controlled mixing of solutions. First, we designed and fabricated the device. The major characteristics of the device are pumpless and having three-dimensional network and mechanical components (rotate and translate) to control the fluidic paths. We injected four different solutions to each inlet of the device and generated the mixed three solutions in the designated orders by rotating and sliding the device. Successful parallel and sequential mixing was verified.

Improvement of microtas for directed evolution of NAD(P)-dependent oxidoreductases

Goto H., Kanai Y., Yotsui A., Shimokihara S., Shitara S., Einaga Y., Matsumoto Y., Miki N., Fujiwara K., Doi N.

22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018 （22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018）  4   2247 - 2249 2018年

ISSN  9781510897571

　概要を見る

Copyright © (2018) by Chemical and Biological Microsystems Society. All rights reserved. Here we report an improved μTAS based on electrochemical measurements and microbeads sorting for screening of NAD(P)-dependent oxidoreductases. By using this system, we measured the activity of model enzymes immobilized on microbeads by detection of NADH with a boron-doped diamond (BDD) electrode in each compartment (∼30 nL) of the microfluidic system. Then, we recovered the magnetic microbeads or the droplets containing genes of enzymes with higher activity by magnetophoretic or dielectrophoretic sorting, respectively. Our μTAS should be useful for directed evolution of various NAD(P)-dependent oxidoreductases with high activity and stability in the future.