Here are wireless battery-free robots that are powered by electromagnetic fields. Researchers at Wyss Institute at Harvard University developed these flat and thin bots to take on complex, repeatable movements. As they explain:

team’s robots are flat and thin (resembling the paper on which they’re based) plastic tetrahedrons, with the three outer triangles connected to the central triangle by hinges, and a small circuit on the central triangle. Attached to the hinges are coils made of a type of metal called shape-memory alloy (SMA) that can recover its original shape after deformation by being heated to a certain temperature. When the robot’s hinges lie flat, the SMA coils are stretched out in their “deformed” state; when an electric current is passed through the circuit and the coils heat up, they spring back to their original, relaxed state, contracting like tiny muscles and folding the robots’ outer triangles in toward the center.

These bots have folding motions that are repeatable and can be controlled to enable complex movements. They may be used in the future inside the body and in other fields.

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