Untethered Microgrippers for Precision Medicine

Microgrippers, a branch of micro/nanorobots, refer to motile miniaturized machines that are of a size in the range of several to hundreds of micrometers. Compared with tethered grippers or other microscopic diagnostic and surgical equipment, untethered microgrippers play an indispensable role in biomedical applications because of their characteristics such as miniaturized size, dexterous shape tranformation, and controllable motion, which enables the microgrippers to enter hard‐to‐reach regions to execute specific medical tasks for disease diagnosis and treatment. To date, numerous medical microgrippers are developed, and their potential in cell manipulation, targeted drug delivery, biopsy, and minimally invasive surgery are explored. To achieve controlled locomotion and efficient target‐oriented actions, the materials, size, microarchitecture, and morphology of microgrippers shall be deliberately designed. In this review, the authors summarizes the latest progress in untethered micrometer‐scale grippers. The working mechanisms of shape‐morphing and actuation methods for effective movement are first introduced. Then, the design principle and state‐of‐the‐art fabrication techniques of microgrippers are discussed. Finally, their applications in the precise medicine are highlighted, followed by offering future perspectives for the development of untethered medical microgrippers. Untethered microgrippers can be manipulated on a microscopic scale and can reach hard‐to‐access regions in the body, holding great promise in precision medicine and personalized medicine. This review is focused on the shape‐morphing mechanisms, actuation methods, design principles, and fabrication techniques of untethered microgrippers. Their representative biomedical applications are highlighted and future prospects are provided.