Designing maneuverable micro-swimmers actuated by responsive gel

Abstract

We use computational modeling to design a self-propelling micro-swimmer that can navigate in a low-Reynolds-number environment. Our simple swimmer consists of a responsive gel body with two propulsive flaps attached to its opposite sides and a stimuli-sensitive steering flap at the swimmer front end. The responsive gel body undergoes periodic expansions and contractions leading to a time-irreversible beating motion of the propulsive flaps, which propels the micro-swimmer. We examine the effects of body elasticity and flap geometry on the locomotion of the swimmer and show how they can be tailored to optimize the swimmer propulsion. We also probe how the swimmer trajectory can be controllably changed using the steering flap that bends when exposed to an external stimulus. We demonstrate that the steering occurs due to two effects: steering flap bending and periodic beating. Furthermore, our simulations reveal that the turning direction can be regulated by changing the stimulus strength.