Cilia metasurfaces for electronically programmable surface-driven microfluidic manipulation*

We report here active metasurfaces of electronically-actuated artificial cilia that can create arbitrary flow patterns in liquids near a surface. We first create voltage-actuated cilia that generate non-reciprocal motions to drive surface flows at tens of microns per second at actuation voltages of 1V. We then show a cilia unit cell that can locally create a range of elemental flow geometries. By combining these unit cells, we create an active cilia metasurface that can generate and switch between any desired surface flow pattern. Finally, we integrate the cilia with a light-powered CMOS clock circuit to demonstrate wireless operation. As a proof of concept, we use this circuit to output voltage pulses with various phase delays to demonstrate improved pumping efficiency using metachronal waves. These powerful results demonstrated experimentally and confirmed using theoretical computations, illustrate a new pathway to fine-scale microfluidic manipulations, with applications from microfluidic pumping to micro-robotic locomotion