A Dual Sensing Modes Capacitive Tactile Sensor For Proximity and Tri-Axial Forces Detection

This study designs and implements a capacitive-type dual-mode (proximity-sensing and force-sensing modes) tactile sensor (Fig. 1) based on the TSMC 0.18 µm 1P6M standard CMOS process. Merits of the dual-mode tactile sensor design are (Fig. 2): (1) Proximity sensing mode: through fringe capacitance change between top electrodes, (2) Tri-axial forces sensing mode: through the gap-closing capacitance change between top and bottom electrodes. Thus, both conductive and non-conductive objects could be detected by capacitive proximity sensing, and normal/shear forces are decoupled by four capacitive sensing elements. Measurements show 4 mm sensing distance in proximity and less than 5% overall crosstalk in tri-axial force sensing.