Microbots could carry sensors and perform medical functions

Developed at the Georgia Institute of Technology, the robots are around 2mm in length, 1.8mm wide and 0.8mm thick, and weigh about five milligrams. They can be powered by vibrations from on-board piezoelectric generators, ultrasound sources or audio speakers. Their developers believe they may be able to work in swarms to sense environmental changes, move materials or even repair injuries inside the human body.

The technology arose from research led by Azadeh Ansari, from Georgia Tech’s School of Electrical and Computer Engineering. “We are working at the intersection of mechanics, electronics, biology and physics. It’s a very rich area and there’s a lot of room for multidisciplinary concepts,” she said.

Each robot consists of a piezoelectric actuator based on lead zirconate titanate (PZT), which vibrates when electric voltage is applied to it. This is glued onto a polymer body which is 3D printed using the process two-photon polymerisation lithography (TPP), which has springy legs that move up and down in response to the vibrations of the actuator: external vibrations from below the surface on which the robot is standing also generates the same effect. The size, diameter, design and overall geometry of the legs determines which frequency the robot will respond to, and the amplitude of vibration determines the speed at which they move. Ansari has created robots that can cover four times their own length in a second.