Details of the Researcher

PHOTO

Soichiro Tottori
Section
Graduate School of Engineering
Job title
Assistant Professor

Research History 1

  • 2023 - Present
    東北大学 工学部 機械知能・航空工学科

Education 1

  • Ph.D. (ケンブリッジ大学)

Professional Memberships 1

  • 応用物理学会

Research Areas 1

  • Nanotechnology/Materials / Nano/micro-systems /

Papers 23

  1. Modeling and design of integrated circuits based on ionic bipolar junction transistors

    Soichiro Tottori, Rohit Karnik

    Physical Review Applied　2025/11/26

    DOI： 10.1103/7r6s-731v 　

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    Biological systems rely on ions and molecules as information carriers rather than electrons, motivating the development of devices that interface with biochemical systems for sensing, information processing, and actuation via spatiotemporal control of ions and molecules. Iontronics aims to achieve this vision by constructing devices composed of ion-conducting materials such as polyelectrolyte hydrogels, but advancing beyond simple single-stage circuit configurations that operate under steady-state conditions is a challenge. Here, we propose and model more complex ionic circuits, namely bistable flip-flop and ring oscillators, consisting of multiple ionic bipolar junction transistors (IBJTs). We begin by modeling and characterizing single IBJTs using both a simplified one-dimensional Nernst-Planck model and a more-detailed two-dimensional Poisson-Nernst-Planck model, elucidating the effects of geometry, size, and fixed charge on the IBJT performance and response time. The one- and two-dimensional models exhibit good agreement, indicating negligible transverse inhomogeneities. Additionally, these models show that reducing the base width improves current amplification, a behavior analogous to electronic BJTs. Building on this understanding, by using the IBJTs as voltage inverters and buffers, we design and model more complex ionic circuits that dynamically change their states in response to ionic signals. Specifically, we demonstrate that the ionic flip-flop retains one-bit memory and that the ring oscillator achieves autonomous periodic self-oscillation without an external clock. Our work provides a foundation for designing dynamic iontronic circuitry using ionic conductors, enabling biochemical signal processing and logic operations based on ionic transport.

  2. Water-triggered self-wrapping and immobilization of an all-organic hydrogel-based cuff electrode

    Shin-ichiro Osawa, Fumiya Imamura, Natsuki Nozaki, Tenyo Ko, Shuto Osaki, Soichiro Tottori, Atsuhiro Nakagawa, Matsuhiko Nishizawa

    Materials Today Bio　2025/10

    DOI： 10.1016/j.mtbio.2025.102248 　

    ISSN： 2590-0064

  3. Porous microneedles: Transdermal salt bridge for biomedical device engineering

    Gaobo Wang, Yuina Abe, Soichiro Tottori, Shuto Osaki, Matsuhiko Nishizawa

    Current Opinion in Biomedical Engineering　2025/09

    DOI： 10.1016/j.cobme.2025.100593 　

    ISSN： 2468-4511

  4. Flexible porous microneedle array for bioelectric skin patch

    Soichiro Tottori, Mirai Matsuura, Sae Ichinose, Haechang Cho, Tarryn Galloway, Natsuho Moriyama, Matsuhiko Nishizawa

    Biomedical Microdevices　2025/06

    DOI： 10.1007/s10544-025-00749-y 　

    ISSN： 1387-2176 1572-8781

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    <jats:title>Abstract</jats:title> <jats:p>Microneedles with porous internal structures can provide pathways for transdermal ionic current and drug delivery by penetrating the stratum corneum of the skin. However, conventional porous microneedle arrays are typically monolithic and rigid, limiting their flexibility and adaptability to curved skin surfaces. To address the issue, a method to directly integrate an array of porous microneedles to a flexible substrate is proposed, preserving their skin penetration capability while enhancing flexibility. The resulting array conforms to curved skin surfaces while effectively reducing transdermal ionic resistance. Numerical and analytical modeling demonstrates that the limited number of needles on a flexible array is sufficient to reduce transdermal resistance. Further, an enzymatic battery is combined to create a fully organic, porous microneedle-based bioelectric skin patch that can generate stable transdermal current suitable for stimulation and drug delivery applications.</jats:p>

  5. Recent advances in iontophoresis-assisted microneedle devices for transdermal biosensing and drug delivery

    Gaobo Wang, Natsuho Moriyama, Soichiro Tottori, Matsuhiko Nishizawa

    Materials Today Bio　2025/04

    DOI： 10.1016/j.mtbio.2025.101504 　

  6. Tunable Electroosmotic Pumping via Electrical Double Layer Charging

    Gaobo Wang, Chenxing Li, Yunhao Sun, Soichiro Tottori, Matsuhiko Nishizawa

    ACS Materials Letters　2025/03/03

    DOI： 10.1021/acsmaterialslett.4c02135 　

    ISSN： 2639-4979

  7. Quantitative evaluation of accelerated transdermal drug delivery by electroosmosis via frustoconical porous microneedles

    Soichiro Tottori, Sae Ichinose, Fumika Sakai, Reiji Segawa, Taiki Yokoyama, Gaobo Wang, Matsuhiko Nishizawa

    Journal of Materials Chemistry B　2025

    DOI： 10.1039/d4tb02583k 　

    ISSN： 2050-750X 2050-7518

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    <jats:p>Performance of electroosmotic flow-based transdermal drug delivery <jats:italic>via</jats:italic> frustoconical porous microneedles is evaluated by quantitative fluorescent analysis of the molecules delivered into skin.</jats:p>

  8. Mussel-inspired thermo-switchable underwater adhesive based on a Janus hydrogel

    Hiroya Abe, Daichi Yoshihara, Soichiro Tottori, Matsuhiko Nishizawa

    NPG Asia Materials　2024/10/11

    DOI： 10.1038/s41427-024-00569-1 　

    ISSN： 1884-4057

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    <jats:title>Abstract</jats:title><jats:p>On-demand underwater adhesives with excellent adhesive and gentle detachment properties enable stable connections to various biomedical devices and biointerfaces and avoid the risk of harmful tissue damage upon detachment. Herein, we present a Janus hydrogel adhesive that can reversibly switch its adhesion strength, which is controlled by temperature, using a thermoresponsive polymer and mussel-inspired molecules. This thermoswitchable adhesive (TSA) hydrogel displays both strong adhesion and gentle detachment with an over 1000-fold gap in underwater adhesion strength onto glass, titanium, aluminum, and Teflon substrates when exposed to temperatures above and below the lower critical solution temperature (LCST). The adhesion switch is possibly caused by the change in toughness of the TSA hydrogels with temperature because the Janus hydrogel possesses gradient crosslinked structures. Moreover, the lowermost surface is sufficiently soft to gently detach from the substrate below the LCST. The electrode-integrated hydrogel remains on human skin, and electrical signals are continuous over 10 min above the LCST. In contrast, commercially available hydrogel electrodes quickly swell and detach from the skin. The thermoswitchability of the TSA hydrogel, with its robust adhesion and gentle detachment, offers significant potential for biomedical applications characterized by minimally invasive procedures.</jats:p>

  9. Bilaterally Aligned Electroosmotic Flow Generated by Porous Microneedle Device for Dual‐Mode Delivery

    Gaobo Wang, Kosuke Kato, Sae Ichinose, Daisuke Inoue, Airi Kobayashi, Hitoshi Terui, Soichiro Tottori, Makoto Kanzaki, Matsuhiko Nishizawa

    Advanced Healthcare Materials　2024/09

    DOI： 10.1002/adhm.202401181 　

    ISSN： 2192-2640 2192-2659

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    <jats:title>Abstract</jats:title><jats:p>Here, a novel porous microneedle (PMN) device with bilaterally aligned electroosmotic flow (EOF) enabling controllable dual‐mode delivery of molecules is developed. The PMNs placed at anode and cathode compartments are modified with anionic poly‐2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid and cationic poly‐(3‐acrylamidopropyl) trimethylammonium, respectively. The direction of EOF generated by PMN at the cathode compartment is, therefore, reversed from cathode to anode, countering the unwanted cathodal suctioning of interstitial fluid caused by reverse iontophoresis. With the bilateral alignment of EOF, the versatility of the proposed device is evaluated by delivering molecules with different charges and sizes using Franz cell. In addition, a 3D printed probe device is developed to ease practical handling and minimize electrical stimulation by integrating two PMNs in closed proximity. Finally, the performance of the integrated probe device is demonstrated by dual delivery of a variety of molecules (methylene blue, rhodamine B, and fluorescein isothiocyanate–dextran) using pig skin and vaccination using mice with delivered ovalbumin.</jats:p>

  10. Transdermal drug delivery using a porous microneedle device driven by a hydrogel electroosmotic pump

    Gaobo Wang, Kosuke Kato, Izuru Aoki, Sae Ichinose, Daisuke Inoue, Soichiro Tottori, Matsuhiko Nishizawa

    Journal of Materials Chemistry B　2024

    DOI： 10.1039/d3tb02208k 　

    ISSN： 2050-750X 2050-7518

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    <jats:p>Integrating a hydrogel electroosmotic pump with a parylene C-coated porous microneedle (PMN) is developed for transdermal drug delivery applications.</jats:p>

  11. Channel-length dependence of particle diffusivity in confinement

    Soichiro Tottori, Karolis Misiunas, Vahe Tshitoyan, Ulrich F. Keyser

    Soft Matter　2021

    Publisher: Royal Society of Chemistry ({RSC})

    DOI： 10.1039/D1SM00289A 　

  12. Irreversible hydrodynamic trapping by surface rollers

    Alexander Chamolly, Eric Lauga, Soichiro Tottori

    Soft Matter　2020

    Publisher: Royal Society of Chemistry ({RSC})

    DOI： 10.1039/C9SM02250C 　

  13. Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles

    Soichiro Tottori, Karolis Misiunas, Ulrich F. Keyser, Douwe Jan Bonthuis

    Physical Review Letters　123　(1)　2019/07/01

    Publisher: American Physical Society ({APS})

    DOI： 10.1103/PhysRevLett.123.014502 　

  14. Controlled Propulsion of Two‐Dimensional Microswimmers in a Precessing Magnetic Field

    Soichiro Tottori, Bradley J. Nelson

    Small　2018/06

    DOI： 10.1002/smll.201800722 　

  15. High-Resolution Vertical Observation of Intracellular Structure Using Magnetically Responsive Microplates

    Tetsuhiko Teshima, Hiroaki Onoe, Soichiro Tottori, Hiroka Aonuma, Takeomi Mizutani, Koki Kamiya, Hirotaka Ishihara, Hirotaka Kanuka, Shoji Takeuchi

    Small　12　(25)　3366-3373　2016/07

    Publisher: Wiley

    DOI： 10.1002/smll.201600339 　

    ISSN： 1613-6810

  16. Formation of liquid rope coils in a coaxial microfluidic device

    Soichiro Tottori, Shoji Takeuchi

    RSC Advances　5　(42)　33691-33695　2015

    Publisher: Royal Society of Chemistry ({RSC})

    DOI： 10.1039/c5ra01037c 　

    ISSN： 2046-2069

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    <p>The coiling of viscous liquid threads in a coaxial microfluidic device is explored and used to fabricate helical hydrogel microfibers.</p>

  17. Wireless Actuation of Micro/Nanorobots for Medical Applications

    Soichiro Tottori, Li Zhang, Bradley J. Nelson

    Nanomedicine　171-189　2014

    Publisher: Springer New York

    DOI： 10.1007/978-1-4614-2140-5_9 　

    ISSN： 1571-5744 2197-7976

  18. Artificial helical microswimmers with mastigoneme-inspired appendages

    Soichiro Tottori, Bradley J. Nelson

    Biomicrofluidics　7　(6)　061101-061101　2013/11

    Publisher: {AIP} Publishing

    DOI： 10.1063/1.4827915 　

    ISSN： 1932-1058

  19. Assembly, Disassembly, and Anomalous Propulsion of Microscopic Helices

    Soichiro Tottori, Li Zhang, Kathrin E. Peyer, Bradley J. Nelson

    Nano Letters　13　(9)　4263-4268　2013/09/11

    Publisher: American Chemical Society ({ACS})

    DOI： 10.1021/nl402031t 　

    ISSN： 1530-6984 1530-6992

  20. Magnetic Helical Micromachines

    Kathrin E. Peyer, Soichiro Tottori, Famin Qiu, Li Zhang, Bradley J. Nelson

    Chemistry - A European Journal　19　(1)　28-38　2013/01/02

    Publisher: Wiley

    DOI： 10.1002/chem.201203364 　

    ISSN： 0947-6539

  21. Bio-inspired microrobots

    Famin Qiu, Li Zhang, Soichiro Tottori, Klaus Marquardt, Krzysztof Krawczyk, Alfredo Franco-Obreg{\'{o } }n, Bradley J. Nelson

    Materials Today　15　(10)　463-463　2012/10

    Publisher: Elsevier {BV}

    DOI： 10.1016/s1369-7021(12)70201-8 　

    ISSN： 1369-7021

  22. Magnetic Helical Micromachines: Fabrication, Controlled Swimming, and Cargo Transport

    Soichiro Tottori, Li Zhang, Famin Qiu, Krzysztof K. Krawczyk, Alfredo Franco-Obreg{\'{o } }n, Bradley J. Nelson

    Advanced Materials　24　(6)　811-816　2012/02/07

    Publisher: Wiley

    DOI： 10.1002/adma.201103818 　

    ISSN： 0935-9648

  23. Selective control method for multiple magnetic helical microrobots

    Soichiro Tottori, Naohiko Sugita, Reo Kometani, Sunao Ishihara, Mamoru Mitsuishi

    Journal of Micro-Nano Mechatronics　6　(3-4)　89-95　2011/06

    Publisher: Springer Science and Business Media {LLC}

    DOI： 10.1007/s12213-011-0035-8 　

    ISSN： 1865-3928 1865-3936

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Books and Other Publications 1

  1. Wireless Actuation of Micro/Nanorobots for Medical Applications (Nanomedicine: Principles and Perspectives)

    Soichiro Tottori, Li Zhang, Bradley J. Nelson

    Springer　2014

    ISBN: 146142139X

Presentations 8

  1. 生体電気スキンパッチのための柔軟多孔質マイクロニードルアレイ

    鳥取 聡一郎, 松浦 未来, 一瀬 彩栄, Cho Haechang, Galloway Tarryn, 森山 夏帆, 西澤 松彦

    第72回応用物理学会春季学術講演会　2025/03/15

  2. Breaking the 500-Dalton Rule of Transdermal Drug Delivery by Locally Stretching Skin with Porous Micropost Array

    Soichiro Tottori, Sae Ichinose, Fumika Sakai, Kotaro Ishikawa, Natsuho Moriyama, Gaobo Wang, Matsuhiko Nishizawa

    PRiME 2024　2024/10/11

  3. Dual-Mode Drug Delivery By Electroosmotic Flow with Bipolar Porous Microneedles

    Sae Ichinose, Kosuke Kato, Natsuho Moriyama, Gaobo Wang, Soichiro Tottori, Matsuhiko Nishizawa

    PRiME 2024　2024/10/11

  4. Water-Triggered Self-Wrapping Cuff Electrodes for Nerve Stimulation

    Fumiya Imamura, Natsuki Nozaki, Soichiro Tottori, Shin-ichiro Osawa, Yuki Anzai, Gaobo Wang, Atsuhiro Nakagawa, Matsuhiko Nishizawa

    PRiME 2024　2024/10/10

  5. Flexible Array of Rigid Porous Microneedles for Bioelectric Skin Patch

    Mirai Matsuura, Soichiro Tottori, Sae Ichinose, Tomoya Nomaguchi, Haechang Cho, Gaobo Wang, Matsuhiko Nishizawa

    PRiME 2024　2024/10/08

  6. Spatiotemporally Controllable Chemical Delivery Via Hydrogel Electroosmotic Pump

    SUN Yunhao, Chenxing Li, Natsuho Moriyama, Gaobo Wang, Soichiro Tottori, Matsuhiko Nishizawa

    PRiME 2024　2024/10/08

  7. Reversible Electrically Modulated Electroosmotic Flow Via Carbon Nanotube Membrane

    Chenxing Li, SUN Yunhao, Natsuho Moriyama, Gaobo Wang, Soichiro Tottori, Matsuhiko Nishizawa

    PRiME 2024　2024/10/08

  8. Iontophoresis Patch with Bipolar Porous Microneedles for Transdermal Dual Delivery

    Soichiro Tottori, Gaobo Wang, Kosuke Kato, Sae Ichinose, Matsuhiko Nishizawa

    IEEE NEMS 2024　2024/05/03

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Research Projects 3

  1. 生体親和性の高い柔軟性を有するイオントロニックデバイスの創成

    鳥取 聡一郎

    System: 公益財団法人 中谷財団 奨励研究 助成金

    2025/04 - 2027/03

  2. イオンダイオードを用いたイオントロニックシステムの構築

    鳥取 聡一郎

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 研究活動スタート支援

    Institution: 東北大学

    2024/07 - 2026/03

  3. 生物を模倣した知的なイオンマシンの創成

    鳥取 聡一郎

    Offer Organization: 公益財団法人 栢森情報科学振興財団

    System: 研究助成

    2020 -

Teaching Experience 2

  1. Experiment 2　Tohoku University, Faculty of Engineering

  2. Experiment I　Tohoku University, Faculty of Engineering