A High Dynamic Range Closed-Loop Stiffness-Adjustable MEMS Force Sensor

We present a microelectromechanical system (MEMS)-based closed-loop force sensor, capable of measuring bidirectional forces along one axis of motion. The device comprises an on-chip electrothermal displacement sensor and electrostatic actuators. It features a voltage-controlled stiffness-adjustment mechanism, providing the user with an additional means of tuning the sensor's characteristics. This siliconon-insulator device is an improvement on our previous design, offering a better dynamic range and a less complex calibration process. The sensor is fabricated based on a standard SOI MEMS process. It is then fully characterized and instrumented with a feedback controller. The closed-loop characterization reveals a 1σ-resolution of 4.74 nN and a force sensing range of -211.7μN to 211.5μN, leading to a dynamic range of 92.9 dB. [2019-0248].