Engineered PWM Drives for Achieving Rapid Step and Settle Times for MEMS Actuation

Microelectromechanical systems (MEMS) provide engineers with a rich palette of technical solutions to a wide range of actuation and sensing challenges. MEMS devices are low cost, easily integrated with sense and drive electronics, are robust, and can be designed to respond to electrical, mechanical, or chemical stimuli. Because they are mechanical, MEMS devices suffer from being relatively slow in comparison with purely electronic devices. However, it has been shown that by using feedforward drives developed using controls theory approaches, it is possible to significantly improve the step and settle time of MEMS actuators. This paper uses this technique to demonstrate the use of pulse width modulation to linearly drive MEMS. Furthermore, it demonstrates an overdrive method capable of improving the step and settle time of a commercial MEMS device by a factor of 1500. The approach is general and can be used for a wide range of devices and actuation methods, such as electrostatic, electromagnetic, and thermal actuation. This provides engineers a simple method to design high Q MEMS devices with sub-millisecond response times, opening the phase space for more micromechanical solutions.