Remote Steering of Self-Propelling Microcircuits by Modulated Electric Field

Abstract

The principles and design of "active" self-propelling particles that can convert energy, move directionally on their own, and perform a certain function is an emerging multidisciplinary research field, with high potential for future technologies. A simple and effective technique is presented for on-demand steering of self-propelling microdiodes that move electroosmotically on water surface, while supplied with energy by an external alternating (AC) field. It is demonstrated how one can control remotely the direction of diode locomotion by electronically modifying the applied AC signal. The swimming diodes change their direction of motion when a wave asymmetry (equivalent to a DC offset) is introduced into the signal. The data analysis shows that the ability to control and reverse the direction of motion is a result of the electrostatic torque between the asymmetrically polarized diodes and the ionic charges redistributed in the vessel. This novel principle of electrical signal-coded steering of active functional devices, such as diodes and microcircuits, can find applications in motile sensors, MEMs, and microrobotics. The direction of self-propulsion of diodes floating on a water surface, powered by external alternating (AC) electric fields, can be controlled on-demand by electronically modifying the symmetry of the applied AC waveform. Changes in the duty cycle of the signal inducing short-lasting DC fields can be used to remotely reverse its direction of motion or make it move sideways.