Robot Leg Motion in a Planarized-SOI, 2 Poly Process

With the ultimate goal of creating autonomous microrobots, we have developed a new five-mask process that combines two polysilicon structural layers with 35 μm thick SOI structures and a backside substrate etch. The polysilicon layers provide 3D hinged structures, high compliance structures, and electrical wiring. The SOI structural layer yields much stronger structures and large-force actuators. On an 8mm x 3mm robot, we have demonstrated polysilicon hinges with SOI electrostatic inchworm motors. This combination allowed us to demonstrate 200 μm out-of-plane motion of a hinged SOI robot leg. Using an off-chip controller, the robot leg was actuated through almost 30o. In addition, we have completed static friction tests of polysilicon flaps to more accurately model the frictional forces of the linkages.