論文 - 三木　則尚

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

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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

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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

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© 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

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© 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

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© 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

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© 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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