Reconfigurable Liquid‐Bodied Miniature Machines: Magnetic Control and Microrobotic Applications

Soft miniature machines demonstrate multimodal actuation and morphology change capabilities in narrow spaces smaller than their dimension. The wirelessly controlled soft-bodied features make them promising candidates for microrobotic manipulation and targeted operation in a noninvasive manner. Liquid-bodied machine offers an ultrasoft body with extreme deformability owing to its fluid nature, enabling adaptive navigation with smooth contact with objects and environmental restrictions. Over the last decade of development, significant research progress has been achieved in wirelessly controlling liquid-bodied machines for diverse manipulation applications. Herein, an overview of the recent research results in magnetic control methods and diverse microrobotic applications of liquid-bodied machines is provided. Considering the control mechanisms and application challenges, ferrofluid-based, liquid metal-based, and liquid marble-based machines are mainly discussed with a brief discussion on droplet-based machines. The connection between control methods and applications is highlighted with a detailed analysis of machine-object and machine-environment interactions. The current challenges and research opportunities on liquid-bodied miniature machines are outlined, aiming at designing intelligent liquid-bodied machine-based microrobotic systems and promoting the development of small-scale robotics.