Single mask, large force, and large displacement electrostatic linear inchworm motors

We have demonstrated a family of large force and large displacement electrostatic linear inchworm motors that operate with moderate to high voltages. The inchworm motor design decouples actuator force from total travel and allows the use of electrostatic gap-closing actuators to achieve large force and large displacement while consuming low power. A typical inchworm motor measures 3 mm x 1 mm x 50 mum and can lift over 130 times its own weight. One motor has achieved a travel of 80 mum and a calculated force of 260 muN at 33 V. The force density of that motor was 87 muN/mm(2) at 33 V and the energy efficiency was estimated at 8%. Another motor displaced the shuttle at an average velocity of almost 4 mm/s and achieved an estimated power density of 190 W/m(3). Motors were cycled 23.6 million times for over 13.5 h without stiction. This family of motors is fabricated in silicon-on-insulator (SOI) wafers using a single mask.