A MEMS based sensor for large scale force measurement

Recent advances on micro-engineering have accelerated the development of MEMS force sensors with large scale and high resolutions. To meet this demand, this paper presents the conceptual design of a new MEMS force sensor with dual-phase characteristics. In the first phase, the sensor possesses an ultra-high resolution that is enough for high precision force measurement. While in the second phase, the resolution is decreased, the measurement range is greatly improved such that the sensor can measure forces within large scale with high resolutions. This function is implemented through a specially designed compliant mechanism with carefully placed hard stoppers. The conceived force sensor features an SOI (Silicon-on-Insulator) body with an integrated capacitive sensor for displacement detecting. The obtained displacement signal is then converted to force information through a calibration procedure. This paper will first present the analytical modeling for both static stiffness and eigenfrequency of the sensor body. Then finite element simulations on both structural and electrical analysis will be demonstrated. Both the analytical and numerical results show that the proposed MEMS force sensor can measure forces ranging from nano-Newton to milli-Newton meanwhile keeps very fine resolutions.