KEIO RESEARCHERS INFORMATION SYSTEM

Message from the Faculty Member 【 Display / hide 】

Message from the Faculty Member 【 Display / hide 】

• I received B.S, and Ph.D. in Applied Physics and Physico-Informatics at Keio University in 2005 and 2009 working with Prof. Yasuhiro Koike on the development of novel polymer optical fibers with the highest bandwidth in the world. I was selected as a Research Fellow of the Japan Society for the Promotion of Science for 2009-2011. After working with Prof. Mitsuhiro Shibayama in University of Tokyo on the gelation mechanism of Tetra-PEG gel in simulation and experiment, I joined the Kumar group as a postdoctoral research scientist in Spring 2013. My current project is self-assembly of polymer grafted nanoparticles. From May 2017 I joined Keio University as Project Assistant Professor with joint appointment as research scientist at Columbia University.

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2019.10

  -

  Present

  Arclev, Inc., Co-Founder / CEO

• 2013.05

  -

  Present

  Columbia University in the City of New York, Chemical Engineering, Research Scientist

• 2017.05

  -

  2019.03

  Keio University, Faculty of Science and Technology, Project Assistant Professor

• 2011.04

  -

  2013.03

  The University of Tokyo, Institute of The Solid State Physics, Research Scientist

• 2009.04

  -

  2011.03

  Keio University, Faculty of Science and Technology, Research Fellow of the Japan Society for the Promotion of Science

Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 2001.04

  -

  2005.03

  Keio University, Faculty of Science and Technology, Applied Physics and Physico-Informatics

  University, Graduated, Other

• 2005.04

  -

  2006.09

  Keio University, School of Integrated Design Engineering

  Graduate School, Completed, Master's course

• 2006.09

  -

  2009.03

  Keio University, School of Integrated Design Engineering

  Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• B.S (Engineering), Keio University, Coursework, 2005.03

• M.S (Engineering), Keio University, Coursework, 2006.09

• Ph.D (Engineering), Keio University, Coursework, 2009.03

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Natural Science / Biophysics, chemical physics and soft matter physics

Research Keywords 【 Display / hide 】

Research Keywords 【 Display / hide 】

• Soft Matter, Self-Assembly, Nanoparticles, Active Matter, Gels, Polymers, Glass Transition

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Elasticity Measurement of Chemical Gel With Laser-Induced Microbubble Dynamics

  Zhao J., Ando K., Asai M., Katashima T., Sakai T.

  Macromolecular Chemistry and Physics 227 ( 1 )  2026.01

  ISSN  10221352

  　View Summary

  The elasticity of Tetra-PEG chemical gel deformed by the oscillation of a laser-induced microbubble was obtained through comparison to a bubble dynamics model. An infrared nanosecond laser pulse was focused into the gel to nucleate a spherical microbubble whose subsequent free oscillation (at frequency of order (Formula presented.)) was recorded using a high-speed camera. The evolution of the bubble radius is found to be symmetric between the growth and shrinkage phases, suggesting that the gel structure is not damaged by finite-amplitude oscillations of the bubble. The radius evolution in the first collapse phase (from the maximal to the minimal size) was compared with the Rayleigh–Plesset (RP) equation equipped with neo-Hookean and quadratic Kelvin–Voigt (qKV) constitutive models, allowing for the determination of the shear modulus under high-frequency deformation. When the maximum radius of the bubble is sufficiently small, the measured shear modulus agrees with values from previous conventional rheometer studies, indicating frequency-independent behavior of the chemical gel above a certain deformation rate threshold. On the other hand, when the maximum radius exceeds a threshold, the neo-Hookean model fails to capture the elastic response, and comparison with the RP equation with the qKV model, reveals pronounced stiffening under large deformation.

  • Access to Document (DOI)

• Oil-sealed RGD-modified alginate hydrogel microwell array for analysis of single-cell-derived extracellular vesicles and particles

  Yamagata C., Hamazaki Y., Nakazato T., Itai S., Honjo M., Kato M., Kurashina Y., Asai M., Hoshino A., Onoe H.

  Microsystems and Nanoengineering 11 ( 1 )  2025.12

  　View Summary

  We propose an oil-sealed, arginine-glycine-aspartic (RGD) -modified alginate hydrogel microwell array for the analysis of single-cell-derived extracellular vesicles and particles (EVPs) secreted by adherent cells cultured in enclosed spaces. Taking advantage of the mesh structure of alginate hydrogel, we developed a microwell array with size-selective permeability that allows nutrients to pass through the hydrogel while preventing EVPs from doing so. Continuous single-cell culture in sealed microwells (>19 days) has been achieved, while retaining the EVPs inside the microwells. The single-cell-derived EVPs were collected from sealed microwells using a glass capillary to analyze surface membrane proteins. We believe that our oil-sealed RGD-modified alginate hydrogel microwell array will contribute to revealing the heterogeneity of cells, thereby advancing our understanding of the mechanisms of various diseases.

  • Access to Document (DOI)

• Three-Dimensional Shape Optimized Seesaw-Type Force Sensor Fabricated with a Micro-Scale 3D Printer

  Sato S., Nakahara Y., Kagawa G., Asai M., Takahashi H.

  Proceedings of IEEE Sensors  2024

  ISSN  19300395

  　View Summary

  This paper proposes a force sensor that utilizes three-dimensional (3D) shape optimization and 3D printing technology. Introduction of micro-scale 3D printing technology have simplified the fabrication processes of microdevices with complex geometries. At the same time, there have also been advancements in the optimization of 3D structures to achieve desirable performances. This study combined these two technologies to develop a force sensor for measuring the force of a soft actuator. The force sensor combines a typical probe geometry with a laser displacement sensor. Due to the millimeter-order scale of the sensor, the low rigidity of the resin material causes undesired torsional deformation. Through 3D shape optimization, a beam design with more than 70 % torsional displacement reduction was achieved without changes in spring constant. Furthermore, a beam printed by a micro-scale 3D printer showed elasticity. The relationship between the input force and laser displacement sensor output showed linear characteristics, indicating its suitability as a force sensor.

  • Access to Document (DOI)

• Oil-Sealed Rgd-Modified Hydrogel Microwell Array with Size-Selective Permeation for Analysis on Exosomes from Single Cells

  Yamagata C., Itai S., Kurashina Y., Asai M., Hoshino A., Onoe H.

  Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems MEMS 2023-January   319 - 322 2023

  ISSN  10846999

  　View Summary

  We propose an oil-sealed arginine-glycine-aspartate (RGD)-modified hydrogel microwell array for analyzing exosomes secreted from single cells. Our device realizes the collection of exosomes from single cells in parallel. The size-selective permeation of the RGD-modified alginate hydrogel allows both stable cell culturing of single or few cells in closed wells and the confinement of exosomes secreted in each space. The nutrients (< 20 nm) that are necessary for cell culture can pass through the hydrogel, while exosomes (30-150 nm) do not permeate the walls of microwells. The cell culture property and the permeability of our device were examined, showing the capability to collect exosomes from single cells. We believe that our device would contribute to understanding the mechanisms of various diseases.

  • Access to Document (DOI)

• Impact of free energy of polymers on polymorphism of polymer-grafted nanoparticles

  Ishiyama M., Yasuoka K., Asai M.

  Soft Matter 18 ( 34 ) 6318 - 6325 2022.07

  ISSN  1744683X

  　View Summary

  Colloidal crystals have gathered wide attention as a model material for optical applications because of their feasibility in controlling the propagation of light by their crystal structure and lattice spacing as well as the simplicity of their fabrication. However, due to the simple interaction between colloids, the colloidal crystal structures that can be formed are limited. It is also difficult to adjust the lattice spacing. Furthermore, colloidal crystals are fragile compared to other crystals. In this study, we focused on polymer-grafted nanoparticles (PGNP) as a possible solution to these unresolved issues. We expected that PGNPs, composed of two distinct layers (the hard core of a nanoparticle and the soft corona of grafted polymers on the surface), will demonstrate similar behaviors as star polymers and hard spheres. We also predicted that PGNPs may exhibit polymorphism because the interaction between PGNPs strongly depends upon their grafting density and the length of the grafted polymer chains. Moreover, we expected that crystals made from PGNPs will be structurally tough due to the entanglement of grafted polymers. From exploration of crystal polymorphs of PGNPs by molecular dynamics simulations, we found face-centered cubic (FCC)/hexagonal close-packed (HCP) and body-centered cubic (BCC) crystals, depending on the length of the grafted polymer chains. When the chains were short, PGNPs behaved like hard spheres and crystals were arranged in FCC/HCP structure, much like the phase transition observed in an Alder transition. When the chains were long enough, the increase in the free energy of grafted polymers was no longer negligible and crystals were arranged in BCC structure, which has a lower density than FCC/HCP. When the chains were not too short or long, FCC/HCP structures were first observed when the volume fraction of system was small, but a phase transition occurred when the system was further compressed and the crystals arranged themselves in a BCC structure. These results most likely have laid strong foundations for future simulations and experimental studies of PGNP crystals.

  • Access to Document (DOI)

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• Entropy-Driven Self-Assembly of Soft Materials

  2020.04

  -

  2025.03

  MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

Awards 【 Display / hide 】

Awards 【 Display / hide 】

• International Young Scientist Fellowship

  2018.04, Chinese Academy of Science, Institute of Physics

  Type of Award： International academic award (Japan or overseas),  Country： China

• International Young Scientist Fellowship

  2018.04, Chinese Academy of Science, Institute of Physics

  Type of Award： International academic award (Japan or overseas),  Country： China

• the Marie Sklodowska-Curie Actions Seal of Excellence

  Makoto Asai, David Wales, 2018.03, European Commission, Entropy Driven Self-Assembly of Soft Materials

  Type of Award： International academic award (Japan or overseas)

• the Marie Sklodowska-Curie Actions Seal of Excellence

  Makoto Asai, David Wales, 2018.03, Entropy Driven Self-Assembly of Soft Materials

• the Marie Sklodowska-Curie Actions Seal of Excellence

  Makoto Asai, Daan Frenkel, 2017.04, European Commission, Predicting polymorphism in self-assembling soft materials

  Type of Award： International academic award (Japan or overseas)

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Courses Taught 【 Display / hide 】

Courses Taught 【 Display / hide 】

• FACTORY VISITING

  2026

• NEW SOCIAL SYSTEM AND TECHNOLOGIES OF SOCIETY5.0(MITSUBISHI CHEMICAL)

  2026

• NEW SOCIAL SYSTEM AND TECHNOLOGIES OF SOCIETY5.0(MITSUBISHI CHEMICAL)

  2025

• INTERNSHIP D(GLOBAL ENVIRONMENTAL SYSTEM LEADERS PROGRAM)

  2025

• INTERNSHIP C(GLOBAL ENVIRONMENTAL SYSTEM LEADERS PROGRAM)

  2025

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Courses Previously Taught 【 Display / hide 】

Courses Previously Taught 【 Display / hide 】

• 環境情報システム構築法

  Keio University

  2018.04

  -

  2019.03

  , 

  Spring Semester, Lecture, Lecturer outside of Keio, 20people

• Environmental Information System Architecture

  Keio University

  2017.04

  -

  2018.03

  , 

  Spring Semester, Lecture, Lecturer outside of Keio, 1h, 20people

Social Activities 【 Display / hide 】

Social Activities 【 Display / hide 】

• Reviewer of Japan Society for the Promotion of Science Postdoctoral Fellowship for Researchers in US and EU

  2016.06

  -

  Present

Memberships in Academic Societies 【 Display / hide 】

Memberships in Academic Societies 【 Display / hide 】

• American Physical Society, 

  2013

  -

  Present