Millirobot Based on a Phase-Transformable Magnetorheological Liquid Metal

Droplet robots have attracted much attention in recent
years due
to their large-scale deformability and flexible mobility in confined
spaces. However, droplet robots are always difficult to maintain rigid
shapes, making them difficult to manipulate objects with large inertia.
Moreover, their low conductivity makes them unable to complete tasks
such as circuit repair. Herein, a millirobot made from magnetorheological
liquid metal is proposed to address the problems. Specifically, the
magnetorheological liquid metal (MLM) robot is made by engulfing iron
particles into gallium–indium alloy, and the mass fraction
of the MLM robot is determined by microscopic observation and rheological
test. The MLM robot possesses both solid and liquid properties, enabling
the robot with plasticity, large-scale deformability, good conductivity,
motion flexibility, and good object manipulation. The MLM robot can
achieve almost all of the functions of existing droplet robots, including
splitting, merging, navigating in narrow channels, and pushing objects.
In addition, it can also accomplish some other tasks that are difficult
for existing droplet robots, such as pulling large objects, repairing
damaged circuits selectively and reversibly, and repairing suspended
circuits through plasticity. The demos show that MLM robots can traverse
narrow spaces and repair circuit damage selectively and reversibly.
It is believed that MLM robots can enrich diverse functionalities
in the future.