論文 - 三木　則尚

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

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© 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

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© 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