Vertically Integrated Multiple Electrode Design for Sensitivity Enhancement of CMOS-MEMS Capacitive Tactile Sensor

Abstract

This study presents novel capacitive tactile sensor designs with vertically integrated double deformable electrodes array (Fig. 1) based on the standard CMOS platform. The proposed designs have also been implemented by the TSMC 0.18 μm 1P6M standard CMOS process and in-house post-CMOS fabrication. The merits of the presented tactile sensors are as follows, (1) vertically integrating double deformable structures with embedded sensing electrodes (Fig. 1c) by using the multi-stacked thin films of CMOS process; (2) electrically connecting the deformable and fixed electrodes to enhance the initial capacitance C ₀ and the capacitance change ΔC under the same footprint; (3) discretizing the sensor into a 5×5 sensing unit array to dramatically reduce the warpage of deformable structures introduced by residual stresses; (4) enhancing sensitivity of tactile sensor using the design of deformable structures. Measurement results show a sensitivity of 0.8%/N for the double-membrane design, and 1.4%/N for the membrane-spring design.