Abstract
With the fast development of robot recently, various related sensors such as tactile and image sensors have received attention. The tactile sensor could enable the robot to realize the contact conditions which are critical to many applications. This study presents a tactile sensor design to enlarge the sensing range by vertically integrated capacitive and piezo-resistive sensing units. The smaller loads are detected by the relatively sensitive capacitive sensing unit with deformable electrode of lower stiffness. As the load exceeding a threshold, the deformable electrode will contact the reference electrode and cause the saturation of capacitive sensing. Meanwhile, the force will transmit to the supporting structure of piezo-resistive sensors. The larger loads are then detected by the piezo-resistive sensing units attached to a relatively stiff supporting structure. Thus, the sensing range of tactile sensor is improved. The presented design is implemented by the TSMC 0.18μm 1P6M standard CMOS process and in-house post-CMOS releasing. After process, the sensitivity and sensing range of tactile sensor can be furtherly tuned by PDMS polymer filled-in.