Researchers at the University of Washington have developed a microrobot with 512 feet. The robot is about the size of a fingernail and weighs about half a gram. Each of the 512 robot feet consists of an electrical wire sandwiched between two materials that expand differently under heat. By passing a current through the electrical wire, one material expands more than the other, making the feet curl.
The small size of the feet results in a very large surface area compared to their volume, which makes it possible to heat up or cool down the feet in less than 20 milliseconds, allowing the robot to take 20-30 tiny steps per second. Another advantage of the bi-metal feet is their strength, allowing the robot to carry more than seven times its own weight.
The researchers are now optimizing the robot for efficiency, to improve its current 10 minute power autonomy, as well as its speed which is currently limited to about 1m per hour.
More information at Robotics Trends