Researchers from Georgia Tech have created microbots so tiny, they make a penny look massive -- and they could one day attack diseases in your body. According to the team's paper, which was accepted for publication in the Journal of Micromechanics and Microengineering, each of the 3D-printed microbots weighs just five milligrams, slightly more than a grain of sand. The team designed the bots to move in response to vibrations produced by anything from a small acoustic speaker to an attached piezoelectric actuator. "As the micro-bristle-bots move up and down, the vertical motion is translated into a directional movement by optimizing the design of the legs, which look like bristles," researcher Azadeh Ansari said in a press release. "The legs of the micro-robot are designed with specific angles that allow them to bend and move in one direction in resonant response to the vibration."