A Linear-Response CMOS-MEMS Capacitive Tactile Sensor

A linear-response capacitive tactile sensor is presented in this work. The sensor was fabricated by the TSMC 0.35 mu m CMOS process and our self-developed MEMS post-process. The structure of the sensor consisted of one pair of parallel electrodes, with the central part of the membrane electrode hollowed out. A pillar with four beams at each side was set at the center to support the membrane electrode. This structure enhanced the uniformity of the deflection, and thus improved the linearity of the response. The wider dynamic range was also obtained because of the stiffer structure. In addition, the buckling of the membrane was lessened. The performance of this design was compared with the conventional parallel plate one. The measured linearity was 0.9728, and the dynamic range was 400mmHg, with the relieved buckling of 0.22 mu m.