Study of anisotropic particles in active bath

Abstract

Brownian (passive) particles undergo random motion due to thermal agitation in the surrounding medium. In recent years, a lot of attention has been devoted to study active Brownian particles, i.e., microscopic particles capable of selfpropelling. Unlike simple passive particles, active particles feature an interplay between random fluctuations and active swimming. Thus, active particles are out of thermal equilibrium and, therefore, they explore their environment completely different from passive particles. Bacteria and other microorganisms are natural examples of active particles that take up energy from their environment and convert into directed (run) motion. Recently, there has been a lot of research progress in the realization of artificial active particles (microswimmers) due to their potential technological applications. We report the anomalous diffusion of anisotropic particles propelled by biological microswimmers (E. Coli Bacteria). The anisotropic particles of various shapes (L-shape, U-shape, cross-shape, Starshape and Z-shape) were fabricated using soft lithography method. We study the motion (translation and rotation) of various anisotropic shaped particles in the thermal and active bath. The results are compared with isotropic (spherical) particles. We observe that shape anisotropy in particle plays a vital role when they are suspended in the bath of E-Coli cells showing different diffusion behavior as the swimming pressure of E-Coli bacteria differs in the shape anisotropy.