This tiny robot from Harvard microrobotics engineers Sam Felton and Robert Wood is a self-assembling plastic robot that is capable of walking — it’s really more of a scooting motion — away in four minutes.
The robot starts as a completely flat, vaguely crab-shaped (technically butterfly-shaped) piece of shape memory plastic. This type of plastic—this is key—changes shape when it’s heated.
The microcontrollers are used to heat the copper tracks, which causes the plastic to fold along the embedded hinges, allowing the robot to move into a standing position. Once it’s all set, the motors allow it to “walk” (scuttle?) on its own.