A High-Resolution MEMS Capacitive Force Sensor With Bionic Swallow Comb Arrays for Ultralow Multiphysics Measurement

Precise force sensing is essential for the mechanical characterization and robotic micromanipulation of biological targets. In this work, a high-resolution microelectromechanical system capacitive force sensor is proposed for measuring ultralow multiphysics. A bionic swallow structure that contained multiple feathered comb arrays is designed for reducing chip dimension and eliminating undesirable mechanical cross-coupling effect. The comb structure is optimized for maximum sensitivity, linearity, and compact chip size. Utilizing a novel interconnection configuration, interferences derived from parasitic capacitance and electrostatic forces exerted negligible effects on the sensor output. The proposed bionic force sensor is fabricated following a simple three-mask process and integrated with application-specific integrated circuit readouts. Its measuring sensitivity is 7.151 fF/nm, 0.529 aF/nN, and 4.247 pF/g for displacement, force, and inclination measurements, respectively. The proposed sensor has a large measurement range of 1000.00 nm and 13.83 μN with a high linearity of 0.9998. The 1-σ resolution is 0.0328 nm and 0.4436 nN, and the noise floor resolution is 0.0044 nm
$\sqrt {\mathbf{Hz}} $
and 0.0597 nN/
$\sqrt {\mathbf{Hz}} $
for displacement and force measurements, respectively. The bias stability of Allan deviance is 0.0050 nm and 0.0678 nN at an integration time of 0.65 s. The proposed bionic swallow sensor exhibits considerable improvement over existing capacitive sensors and feasibility for ultralow multiphysics measurement in biomedical applications.