My ultimate goal for my research is understanding the way living structures are made up.
If I say living structures, many people will imagine life on earth, say animals, plants, and so on. But what I mean with living structures also includes nations, societies, and relationships with friends in more familiar things. They have small units that behave independently and also almost randomly. However, through local interactions between such active units, mass of such units behaves as if it has other intention, and it has distinct order. I'd like to understand mechanisms and underlying universality that promotes such structure formation.
To consider such phenomena especially from a view standpoint of physics, statistical mechanics and thermodynamics are key field. Statistical mechanics can be said to be a field which succeeded in predicting the collective behavior of simple and ideal units, such as molecules. One key for this success is that extraordinary larger number of units constitutes a group. Another field, thermodynamics, puts observation of macroscopic physical quantity as a start point. It is with dare to ignore internal details, and succeed in finding a relation between these macroscopic observable.
These field in common assumes that a system is in a thermal equilibrium condition. This is strikingly useful concept/approximation. However, the unit which constitutes living structure is under continuous input of energy, and many are not in a thermal equilibrium situation. Moreover, in many cases, it has also input of constituents particles. Such a system us called as nonequilibrium open system, or far from equilibrium system.
In a nonequilibrium open system, the concept of a thermal equilibrium can be used only locally. So the understanding of a nonequilibrium open system is still on-going. On the other hand in a nonequilibrium open system, a various phenomenon with amazingly beautiful pattern formation occurs, as well as in human societies.
I am using the technique of the both sides of an experiment and theory to understand this nonequilibrium open system, and aim to unveil the physical side of a life process.
Here, if there is inhomogeneous surfactant distribution, there occurs sear stress to make flows that reduce this inhomogeneity. This phenomenon is called solutal Marangoni effect (Please check solutal Marangoni page (under construction) ). This solutal Marangoni effect is one of chemo-mechanical energy transduction systems under isothermal condition. Through analysis of this system, I want to reveal physics of chemo-mechanical energy transduction.
(More including movies)
Phys. Rev. Lett., 94, 068301 (2005)
Movie Page from Mr. Ken Nagai
Phys. Rev. E, 71, 065301 (2005)
"Rotational motion of a droplet induced by interfacial tension",
Phys. Rev. E 87, 013009 (2013).
 H. Kitahata, N. Yoshinaga, K. H. Nagai and Y. Sumino
"Spontaneous motion of a Belousov-Zhabotinsky reaction droplet coupled with a spiral wave",
Chem. Lett. 41, 1052-1054 (2012).
 N. Yoshinaga, K. H. Nagai, Y. Sumino and H. Kitahata
"Drift instability in the motion of a fluid droplet with a chemically reactive surface driven by Marangoni flow",
Phys. Rev. E 86, 016108 (2012).
T. Yamaguchi, H. Muroo, Y. Sumino, and M. Doi
"Asymmetry-symmetry transition of double-sided adhesive tapes",
Phys. Rev. E 85, 061802 (2012).
 Y. Sumino, H. Shibayama, T. Yamaguchi, T. Kajiya and M. Doi
"Failure of film formation of viscoelastic fluid: Dynamics of viscoelastic fluid in a partially filled horizontally rotating cylinder",
Phys. Rev. E 85, 046307 (2012).
 Y. Sumino, K. H. Nagai, Y. Shitaka, D. Tanaka, K. Yoshiakwa, H. Chaté and K. Oiwa
"Large-scale vortex lattice emerging from collectively moving microtubules",
Nature 483, 448–452 (2012)
Nature News&Views "Biological physics: Swarming microtubules" by Tamás Vicsek Nature 483, 411-412 (2012)
Press Release by CEA (English), by NICT (Japanese), by CEA (French)
 Y. Sumino, H. Kitahata, Y. Shinohara, N. L. Yamada and H. Seto
"Formation of a multi-scale aggregate structure through spontaneous blebbing of an interface",
Langmuir 28,3378−3384 (2012)
 H. Kitahata, N. Yoshinaga, K. H. Nagai, and Y. Sumino
"Spontaneous motion of a droplet coupled with a chemical wave",
Phys. Rev. E 84, 015101(R)(2011)
Presented as PRE Kaleidoscope Images: July 2011
 Y. Sumino, H. Kitahata, H. Seto and K. Yoshikawa
"Dynamical blebbing at a droplet interface driven by instability in elastic stress: a novel self-motile system",
Soft Matter 7, 3204-3212 (2011)
Presented as Hot article.
 H. Kitahata, K. Kawata, S. Takahashi, M. Nakamura, Y. Sumino and S. Nakata
"Synchronized motion of the water surfaces around two fixed camphor disks",
J. Colloid and Interface Sci. 351, 299-303 (2010).
 Y. Sumino, H. Kitahata, H. Seto, S. Nakata and K. Yoshikawa
"Spontaneous deformation of an oil droplet induced by the cooperative transport of cationic and anionic surfactants through the interface",
J. Phys. Chem. B 113, 15709-15714 (2009)
 H. Kitahata, J. Taguchi, M. Nagayama, T. Sakurai, Y. Ikura, A. Osa, Y. Sumino, M. Tanaka, E. Yokoyama and H. Miike
"Oscillation and Synchronization in the Combustion of Candles",
J. Phys. Chem. A 113, 8164-8168 (2009)
 S. Nakata, K. Ishibashi, K. Kawata, Y. Sumino, S. Nakanishi and K. Sonoda
"A liquid/liquid interface excited by stimulation with water",
J. Colloid and Interface Sci. 332, 254-257 (2009)
 Y. Sumino and K. Yoshikawa
"Self-motion of an oil droplet: A simple physico-chemical model of active Brownian motion",
Chaos 18, 026106 (2008)
 H. Kitahata, K. Kawata, Y. Sumino and S. Nakata
"Oscillation of a water surface in contact with a fixed camphor disk",
Chem. Phys. Lett. 457, 254 (2008)
 Y. Sumino, H. Kitahata, H. Seto and K. Yoshikawa
"Blebbing dynamics in an oil-water-surfactant system through the generation and destruction of a gel-like structure",
Phys. Rev. E 76, 055202 (2007)
 K. Nagai, Y. Sumino and K. Yoshikawa
"Regular self-motion of a liquid droplet powered by the chemical marangoni effect",
Colloid. Surf. B 56, 197-200 (2007)
 K. Nagai, Y. Sumino, H. Kitahata, and K. Yoshikawa
"Change in the Mode of Spontaneous Motion of an Alcohol Droplet Caused by a Temperature Change",
Prog. Theor. Phys. Suppl. 161, 286-289 (2006)
 Y. Sumino, N. Magome and K. Yoshikawa
"An oil droplet that spontaneously climbs up stairs",
Prog. Theor. Phys. Suppl. 161, 348-351 (2006)
 H. Kitahata, Y. Sumino, K. Nagai and K. Yoshikawa
"Autonomous motion of droplet powered by chemical potential and by photon-flux",
2005 IEEE International Symposium on Micro-NanoMechatronics and Human Science 115-119 (2005)
 Y. Sumino, H. Kitahata, K. Yoshikawa, M. Nagayama, S-i. M. Nomura, N. Magome, and Y. Mori
"Chemosensitive Running Droplet",
Phys. Rev. E 72, 041603 (2005)
 K. Nagai, Y. Sumino, H. Kitahata and K. Yoshikawa
"Mode Selection in the Spontaneous Motion of an Alcohol Droplet",
Phys. Rev. E 71, 065301 (2005)
 Y. Sumino, N. Magome, T. Hamada and K. Yoshikawa,
"Self-Running Droplet: Emergence of Regular motion From Nonequilibrium Noise."
Phys. Rev. Lett. 94, 068301 (2005)
Nature News&Views "Oiled Acrobatics" by Magdalea HelmerNature 433,693 (2005)
Physical Review Focus 15, story 7
"Pattern Formations and Oscillatory Phenomena" Elsevier, Chapter 3 "Dynamics of Droplets"
Grant-in-aid for Research Activity Start-up, 23840019
Research fellowship from the Japan Society for the Promotion of Science (JSPS) for Young Scientists (DC1)(Apr. 2006 - Mar. 2009)
Research fellowship from the Japan Society for the Promotion of Science (JSPS) for Young Scientists (PD)(Apr. 2009 - Mar. 2012)
Satellite meeting of Statphys25 "Patterns & waves in populations of cells and active particles"
Wetting and Capillarity in Complex Systems (WCCS13)
Instabilities and Control of Excitable Networks: From macro- to nano-systems(ICENet2012)
Phase Transition Dynamics in Soft Matter :Bridging Microscale and Mesoscale
International Symposium on Complex Systems 2011
DYNACT11 Collective Dynamics and Pattern Formation in Active Matter Systems.
18th Ostwald Kolloquium: Dynamic Wetting of Complex Liquids.
Korea University-the University of Tokyo 1st Joint Workshop on Bio-Soft Matter
ICSF2010 Satellite Meeting - Contact and stick-slip dynamics in sliding friction
International Symposium on Non-Equilibrium Soft Matter 2010
5th Pacific Rim Conference of Rheology
First GSC Tanabata Meeting
International Soft Matter Conference
Solvay International Workshop on ``Chemo-hydrodynamic patterns and instabilities''
Workshop on Active Matter - Physics of Biokinetics -
Gordon Research Conference on Oscillations and Dynamic Instabilities In Chemical Systems
International Symposium on Non-Equilibrium Softmatter
2008 AAAS Annual Meeting
Nonlinear Collective Behaviour: Networks, Swarming and Reaction Diffusion Dynamics
Gordon Research Conference: Oscillations and Dynamic Instabilities in Chemical Systems
9th Tamura Symposium, Frontiers in Dynamics: Physical and Biological Systems
Dynamics Days 2006
International Symposium on Physics of Non-Equilibrium Systems
Summer School on Design and Control of Self-Organization in Physical, Chemical and Biological Systems
International Symposium on Oscillation, Chaos and Network Dynamics in Nonlinear Science (Poster Presentation)
International Workshop on Dynamics of Complex Fluid (Poster Presentation)