Ibuki Kawamata | Searcharxiv

arXiv2026

Semantic analysis of behavior in a DNA-functionalized molecular swarm

In this paper, we propose applying semantic embedding to learn the range of behaviors exhibited by molecular swarms, thereby providing a richer set of features to optimize such systems. Specifically, we consider a standard molecular swarm where the individuals are cytoskeletal filaments (called microtubules) propelled by surface-adhered kinesin motors, with the addition of DNA functionalization for further control. We extend a microtubule model with that additional interaction and show that the extracted semantic atoms from simulation results match the expected behaviors. Moreover, the decomposition of each frame in the simulations accurately describes the expected impact of the external control values. Those results provide relevant leads towards the explainability of simulated experiments, making them more reliable for designing and optimizing in-vitro systems.

cs.RO↗

arXiv2026

Self-Viscophoresis: Autonomous Motion by Biasing Thermal Fluctuations via Self-Generated Viscosity Asymmetry

Microscale transport often relies on ubiquitous yet intrinsically random thermal fluctuations. Understanding how such fluctuations can be biased into directed motion has long been a central theme of nonequilibrium physics. Here, we introduce self-viscophoresis, a mechanism of autonomous motion based on the rectification of thermal fluctuations in a self-generated nonequilibrium viscosity field. Asymmetric colloidal particles dispersed in a thermoresponsive polymer solution induce local heating under uniform illumination, producing a spatially asymmetric viscosity profile around the particle and resulting in persistent directed motion. To elucidate the physical origin of this behavior, we develop a minimal Langevin model coupling isotropic thermal fluctuations to a dynamically updating temperature-viscosity field. The model shows that viscosity asymmetry anisotropically damps stochastic dynamics, effectively biasing thermal fluctuations into a net drift. It thus reproduces the observed directed motion without invoking deterministic propulsion terms associated with effective potentials or environmental fluid flows. Our results distinguish self-viscophoresis from conventional self-propulsion mechanisms and establish it as a general framework enabling reversible control of both the direction and dimensionality of motion.

cond-mat.soft↗