Power delivery and locomotion of untethered micro-actuators

This paper presents a micro-actuator that operates free of any physically restraining tethers. We show how capacitive coupling can be used to deliver power to MEMS devices, independently of the position and orientation of those devices. Then, we provide a simple mechanical release process for detaching MEMS devices from the fabrication substrate once chemical processing is complete. To produce these untethered micro-actuators in a batch-compatible manner while leveraging existing MEMS infrastructure, we have devised a novel post-processing sequence for the PolyMUMPS process. Through the use of this sequence, we show how to add, post hoc, a layer of dielectric between two previously-deposited polysilicon films. We have demonstrated the effectiveness of these techniques through the successful fabrication and operation of untethered scratch drive actuators. Locomotion of these actuators is controlled by frequency modulation, and the devices achieve speeds of over 1.5 mm/sec.