A novel polymer filled CMOS-MEMS inductive-type tactile sensor with wireless sensing capability

This study presents a novel wireless inductive type CMOS-MEMS tactile sensing unit composed of underneath sensing coil and deformable polymer layer. The advantages of the proposed tactile sensing unit are as follows, (1) No released sensing diaphragm on the sensing unit. Thus, the residual stress caused by CMOS-MEMS process can be avoided. (2) The sensing coil underneath is protected by the above polymer layer, so the sensing unit would not be damaged under applied load. (3) Wireless sensing capability due to the magnetic coupling. (4) Sensing range can be modulated by varying the stiffness of the polymer (e.g. changing the ratio of pre-polymer and curing agent). This tactile-sensing unit is implemented using TSMC 0.18μm 1P6M CMOS process, in-house post-CMOS releasing, and polymer filling. Experiments show the tactile sensor has the sensitivity of 0.02%/mN within the sensing range of 0-80mN, and the wireless sensing ability is also demonstrated.