Design of a MEMS-based resonant force sensor for compliant, passive microgripping

In this paper, a polysilicon double-ended tuning fork (DETF) is proposed for use as a force sensor for integration into a compliant, passive microgripper used in a microassembly of 3D MEMS structures. The force sensor is also designed to operate in a manner similar to scanning probe microscopy (SPM) that is commonly utilized to study surface properties and topography of material. The design, modeling, and performance characteristics of the resonant force sensor are addressed. The force sensor design has a resolution of 1.0 pN/√Hz: in absence of electronics and power noises. Furthermore, a gauge factor (i.e. sensitivity) of 1700 is obtained with applied force of 30 μN. A DETF excitation and detection technique is proposed to minimize parasitic capacitance effects.