Modeling and Experimental Characterization of an Active MEMS Based Force Sensor

Abstract

Active force sensors are based on the principle of force balancing using a feedback control. They allow, unlike passive sensors, the measurement of forces in a wide range with nanoNewton resolutions. This capability is fundamental when dealing with the mechanical characterization of samples with a wide range of stiffness. This paper deals with the modeling and the experimental characterization of a new active MEMS based force sensor. This sensor includes folded-flexure type suspensions and a differential comb drive actuation allowing a linear force/voltage relationship. A control oriented electromechanical model is proposed and validated experimentally in static and dynamic operating modes using a stroboscopic measurement system. The sensor has a resonant frequency of 2.2 kHz, and a static passive measurement range of $\pm 2.45\mu \mathbf{N}$. This work is the first step toward new dynamic measuring capabilities and sensing at the micro/nano-scales when high dynamic, large measurement range and nanoNewton resolution are required.