A switched actuation and sensing method for a MEMS electrostatic drive

MEMS technology is being investigated to improve the performance, integration and cost of nanopositioning systems. The most basic MEMS fabrication processes produce designs etched into a single layer of silicon and electrostatic transduction is often seen as the most viable actuation and sensing technology. This work provides a method to utilize the same electrostatic drive for both actuation and sensing functions. By combining both functions into the one drive, an effective increase in actuator force and sensor sensitivity can be achieved. The sensor utilizes a sigma-delta type arrangement to create a displacement-to-digital converter. With the actuator composed of a switching amplifier, this allows the nanopositioner to be controlled directly from a DSP platform. This work outlines the design of the nanopositioning system, provides the system modeling and identification and characterizes the open loop performance of the nanopositioner.