Interface electronics design for POSFET devices based tactile sensing systems

This work presents the development of novel POSFET (Piezoelectric Oxide Semiconductor Field Effect Transistor) devices based tactile sensing system. The tactile sensing system, primarily developed for the robotic applications, consists of 5×5 POSFET touch sensing array and the associated read out and data acquisition system. The POSFET touch sensing devices are obtained by spin coating piezoelectric polymer P(VDF-TrFE), poly(vinylidene fluoride – trifluoroethylene), film on the gate area of MOS (Metal Oxide Semiconductor) devices and polarizing the film in situ. To detect contact events, the taxels utilize the contact forces induced change in the polarization level (and hence change in the induced channel current) of piezoelectric polymer. Both, individual taxels and the array are designed to match spatio-temporal performance of the human fingertips. The data acquisition system is implemented with off-the-shelf electronic components and its design takes into account both the application related requirements as well as the constraints posed by existing hardware on the humanoid robot ‘iCub’. The biasing scheme for using POSFET devices and the problems thereof are also been discussed.