Wireless Electrohydrodynamic Actuators for Propulsion and Positioning of Miniaturized Floating Robots

Autonomous soft robots require compact actuators generating large strokes and high forces. Electro-fluidic actuators are especially promising, they combine the advantages of electroactive polymers (low-power consumption, fast response, and electrical powering) with the versatility of fluidic systems (force/stroke amplification). EHD (electrohydrodynamic) actuators are electro-fluidic actuators whose motion results from charges being induced and accelerated in a liquid. They are extremely compact, silent, and low power (<= 10 mW). They have been recently demonstrated in stretchable pumps and for the wireless propulsion of simple floating robots. This study demonstrates simultaneous wireless propulsion (2.5 mm s(-1)) and control of a 1 cm sized robot using a single DC signal. Voltage is applied between an electrode on the floating robot and a fixed one, both exposed to a dielectric liquid. Results support the underlying physical mechanism as EHD and characterize robot motion with different fluorocarbon liquids and voltages between 400 and 1800 V. Path following is demonstrated with a 3 x 3 array of electrodes. EHD actuators prove to be a simple, compact, low power alternative to magnetic and acoustic actuators for wireless powering and control of miniaturized robots, with applications in precision assembling at the micro/mesoscale, lab-on-chip, tactile displays, and active surfaces.