Purcell's three-link microswimmer based on IPMC: Simulations in COMSOL Multiphysics

One of the few possible mechanisms for self-propulsion at low Reynolds number (henceforth, Re) is undulations of an elastic tail, as proposed in the classical work of Purcell in 1977. This paper studies this effect by investigating a variant of Purcells three-link swimmer model where the lateral links are flexible, specifically fabricated by ionic polymer metal composite (IPMC), by means of simulations in COMSOL Multiphysics. Firstly, a model of the material is developed in COMSOL and simulated in comparison with results that can be found in the literature. The proposed model presents some benefits against other existing models: 1) it allows actuator displacement, so it can be integrated in the model of a mobile robot; 2) it satisfies Euler-Bernoulli theorem; and 3) it incorporates the interaction of the actuator with a fluid in which the robot is immersed. Based on this model, a Purcell's three-link microswimmer is built whose lateral links are of IPMC within a fluid under low Re conditions. The displacement of the robot is analyzed for one of the classical primitives of motion, namely, the circular primitive. The results demonstrate that the swimmer is able to perform a non-reciprocal motion and, consequently, propel itself within the fluid.