A Steerable, Untethered, 250 × 60µm MEMS Mobile Micro-Robot

We present a steerable, electrostatic, untethered, MEMS micro-robot, with dimensions of 60 μm by 250 μm by 10 μm. This micro-robot is 1 to 2 orders of magnitude smaller in size than previous micro-robotic systems. The device consists of a curved, cantilevered steering arm, mounted on an untethered scratch drive actuator. These two components are fabricated monolithically from the same sheet of conductive polysilicon, and receive a common power and control signal through a capacitive coupling with an underlying electrical grid. All locations on the grid receive the same power and control signal, so that the devices can be operated without knowledge of their position on the substrate and without constraining rails or tethers. Control and power delivery waveforms are broadcast to the device through the capacitive power coupling, and are decoded by the electromechanical response of the device body. Individual control of the component actuators provides two distinct motion gaits (forward motion and turning), which together allow full coverage of a planar workspace (the robot is globally controllable). These MEMS micro-robots demonstrate turning error of less than 3.7◦/mm during forward motion, turn with radii as small as 176 μm, and achieve speeds of over 200 μm/sec, with an average step size of 12 nm. They have been shown to operate open-loop for distances exceeding 35 cm without failure, and can be controlled through teleoperation to navigate complex paths. A revised version of this paper has appeared in the proceedings of the 12th International Symposium of Robotics Research (ISRR 2005), San Francisco, CA, October 12th-15th, 2005. Dartmouth Computer Science Technical Report 2005-564 http://www/cs.dartmouth.edu/reports/abstracts/TR2005-564 2 B. R. Donald et al