Chemotaxis of two chiral squirmers

Abstract

External gradients can strongly influence the collective behavior of microswimmers. In this paper, under an external linear chemical gradient, we study the behavior of two hydrodynamically interacting self-propelled chiral swimmers in the low-Reynolds number regime. We use the generalized squirmer model called the chiral squirmer, a spherically shaped body with an asymmetric surface slip velocity, to represent the swimmer. We find that the external gradient favors the attraction between the swimmers and, in some situations, leads to a bounded state in which the swimmers move in a highly synchronous manner. Furthermore, due to this cooperative motion, these swimmers reach the chemical target faster than individual swimmers. This study may help in understanding the collective behavior of chiral swimmers and in designing synthetic microswimmers for targeted drug delivery.