Driving modes and characteristics of biomedical micro-robots

Micro-robots (MRs) are miniature machines with dimensions smaller than 1 mm and have semi- or fully-autonomous capabilities, including sensing, decision-making, and performing operations. These MRs have garnered significant attention in the precision medicine and personalized treatment field due to their ability to navigate narrow areas of the human body with non-desirable fluid flow. Specifically, MRs are actuated by a mechanism that generates propulsive force through the interaction between MRs' actuation modules and external energy sources in a specific direction. This driving mechanism enables the precise execution of medical treatment such as targeted drug delivery and minimally invasive surgeries. Nonetheless, MRs currently encounter certain challenges in clinical practice, including reliance on external energy sources, short lifespan, and difficulties in degradation or recovery within the human body. This article aims to review the common components and characteristics of driving mechanism for MRs' actuation modules, propose possible solutions to address current clinical challenges, and ultimately, explore the desirable structural and functional composition for the future development of MRs. Through these efforts, this review hopes to provide guidance for the future development of MRs in the field of precision medicine.