Autonomous Self-Propelling Microcircuit Particles

摘要

We show that various types of miniature semiconductor diodes floating in water act as self-propelling particles when powered by external alternating electric field. The millimeter-sized diodes rectify the voltage induced between their electrodes. The resulting electro-osmotic force propels them in the direction of either the cathode or the anode depending on their surface charge. The motion of these rudimentary self-propelling micromachines can be controlled by internal logic. The semiconductor elements could emit light or respond to light, move at internally controlled speed and could be used as propellers for rotating freely-suspended 'gears' and future autonomous micromachines. Diodes embedded into walls of microfluidic channels provide locally distributed pumping or mixing functions powered by a global external field. The combined application of AC and DC fields in such devices allows decoupling the velocity of the particles and the liquid and could be used for on-chip separations.