Using Actuated Cilia to Regulate Motion of Microscopic Particles

Marine animals use microscopic elastic filaments, or cilia, to capture food particles that are suspended in the surrounding solution [1, 2]. In the respiratory tract, active cilial layers facilitate the transport of particulates such as dust or mucous. These motile cilia experience the surrounding fluid as a highly viscous, low Reynolds number environment, where the effects of inertia are negligible [2]. Nevertheless, by oscillating in a periodic, time-irreversible manner, the elastic cilia can generate net currents within the fluid and thereby, effectively transport and direct microscopic particles. The behavior of these biological cilia provides a useful design concept for creating microfluidic devices where actuated “synthetic cilia” would regulate the movement of micrometer-sized particles, such as biological cells and polymeric microcapsules.