On the detection interfaces for inductive type tactile sensors

Abstract

This study presents the investigation of detection interface for the inductive type tactile sensor consisted of a polymer encapsulated CMOS chip with coils and a magnetic bump. The normal tactile load will change the distance between the magnetic bump and coils, and the tactile load is then detected by the magnetic flux change of the coils. Thus, the detection interfaces include (1) the magnetic bump which acts as the contact interface, and (2) the coils (on the CMOS chip) which act as the signal pick-up interface. For the contact interface, the size and material of the magnetic bump will influence the magnetic flux of the inductive tactile sensor. The signal outputs resulted from the magnetic tactile bumps of different materials and sizes are studied. Moreover, the force responses, hysteresis measurements, and misalignment issues for magnetic bumps of different sizes are also investigated. For signal pick-up interface, two coil designs are presented to offer different sensing approaches for the inductive tactile sensor. Since the CMOS chip is implemented using the commercially available standard process (the TSMC 0.35 μm 2P4M CMOS process), multi-layer coils are achieved by using the four metal films.