Advanced Microrobots Driven by Acoustic and Magnetic Fields for Biomedical Applications

Microrobots driven by magnetic and acoustic fields have shown great potential in multiple biomedical applications due to their excellent biocompatibility, wireless actuation, access to confined environments, and tissue penetration. A single physical actuation method often meets inevitable limitations and complications, such as the limited propulsion of the magnetic actuation and difficult direction control of the acoustic actuation. This review summarizes the current progress of hybrid magneto-acoustic actuation to address the limitations of single magnetic or acoustic actuation. First, we review the research on microrobots driven by single magnetic and acoustic fields and clarify the properties of each physical actuation. Then, we summarize 2 forms of hybrid magnetic-acoustic actuation: (a) magnetic steering and acoustic propulsion and (b) magnetic propulsion and acoustic manipulation. The state-of-the-art applications of magneto-acoustic microrobots, including targeted drug delivery, minimally invasive surgery, and medical imaging, are presented to demonstrate their great potential in biology and clinics. This article finally discusses current challenges and potential developments in magneto-acoustic robotics to provide a reliable path for designing and applying hybrid magneto-acoustic actuation methods.