Large-Displacement Vertical Electrostatic Microactuator Dynamics using Duty-Cycled Softening/Stiffening Parametric Resonance.

Electrostatic microactuators with large vertical scanning range (several hundred microns) at high frequency (hundreds to thousands of hertz) and chips sizes compatible with endoscopic microscopy have recently been demonstrated based on parametric resonance. This paper examines the use and modeling of mixed softening/hardening dynamics to help produce large ranges of motion in this class of mirrors. Origin of spring stiffening behavior in actuator design is described, followed by non-dimensional analysis of actuator motion trends. Experimental results are presented for a sample actuator design with up to 480 μm displacement at 1225 Hz and 60 V. Comparison to predicted trends and comments on benefits and limitations of modeling are provided.