Bio-inspired tactile sensing arrays

Abstract

This work presents the development of tactile sensing arrays, inspired by cutaneous sensing in humans, for the fingertips of a humanoid robot. The tactile sensing arrays have been developed in two phases. Microelectrode arrays (MEA), having 32 sensing elements - each epoxy adhered with 25μm thick piezoelectric polymer (PVDF-TrFE) film, were fabricated in the first phase. When connected to the gate of FET devices (external to the chip), each element on MEA acts like an extended gate; thereby facilitating modulation of charge in the induced channel by the charge generated in PVDF-TrFE film - as a result of applied force. Thus, each sensing element converts force into voltage. The tactile sensing arrays developed in second phase work on the same principle but are free from any extended gate. These arrays (having 25 sensing elements) use POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistors) touch sensing elements - in which, piezoelectric polymer film is directly spin coated on the gate area of the FET devices. Thus, a POSFET touch sensing element 'senses and partially processes at same site' - as is done by receptors in human skin. The spatial-temporal performance of these chips is similar to that of skin in the human fingertips.