A High-Resolution Flexible Tactile Imager System Based on Floating Comb Electrodes

Flexible high-resolution contact force imagers are needed in many applications for robotic grippers and gait analysis, but its intrinsic intimate contact requirement often causes breaking of top metallization layers and failure in a short time. The use of floating electrodes has significantly improved the reliability of traditional quad-cell capacitive tactile sensing devices. In this paper we present a new type of high-resolution (676-sensors) flexible pressure/shear imager array based on floating combs. Each sensing cell consists of two sets of orthogonal comb electrodes connected in a differential capacitance configuration. The shear sense direction (+x, -x, +y, -y) is determined by the amount of asymmetric comb overlap. Pressure readouts are obtained from the net capacitance of the cell. The new comb configuration multiplies the shear capacitive signal by the number of combs per cell. The imager is read using a high-speed switched-capacitor circuit with a 12-bit resolution at full frame rates of 100 Hz (similar to 0.8Mb/s).