Fin Thruster on Acoustic Resonator (Ftar) for Micro Swimming Robots

This paper presents a fin thruster on acoustic resonator (FTAR) having the following unique advantages: (1) strong propulsion demonstrating up to ~60 cm/s swimming speed; (2) long longevity due to encapsulated cavity resonator, (3) no requirement for ultra flexibility in the device material; and (4) good frequency tunability allowing for activating only desired thrusters among many by matching the resonant frequencies and thus for multi-direction steering of a microswimmer when equipped with multi FTARs. The FTAR has an acoustic resonator encapsulated by a thin diaphragm on which fins are mounted. The oscillation of fins amplified by the resonator diaphragm oscillation generates strong propulsion. The characterizations in propulsion and longevity of the designed and fabricated FTARs are presented. By selectively activating 2 FTARs in an untethered microswimming robot, remotely controllable 2-D steered navigations in a microchannel are demonstrated.