Programmable Acoustofluidic-Powered Miniaturized Robot for Two-Dimensional Swimming

Miniaturized swimming robots have been widely explored for navigation and precise manipulation in low Reynolds number fluids, showing great potential in biomedical applications. In this work, we propose an asymmetric-pattern Lamb wave resonator (LWR) at an operating frequency of 148 MHz and demonstrate it as a wireless driver for two-dimensional swimming robotics. Experimental results show that the resonator immersed in water could generate strong acoustic streaming with highly directional drag forces even under applied powers of ~100 mW. The LWRs are fabricated with standard semiconductor process, leading to convenient design of the operating frequency and device layout. Both the linear motion with a speed of several mm/s and rotation with a speed of more than $100~^{\circ }$ /s have been realized using a four parallelly connected LWR array as the driver. Therefore, by precisely controlling the movement direction and speed of the robot, flexible two-dimensional swimming has been achieved. This work presents a strategy of microscale acoustofluidic principle for the development of miniaturized two-dimensional swimming robots, inspiring the exploration of tiny robots in minimally invasive surgery and drug delivery domains.[2024-0183]