Spike-Based Readout of POSFET Tactile Sensors

We present a low-power compact circuit for the event-driven readout of tactile sensors. The taxel is based on the POSFET device, a sensotronic unit where a piezo-electric material is deposited on the gate of a transistor, integrated with a Leaky-Integrate and Fire neuron circuit. This device encodes the applied force with trains of digital pulses, using the asynchronous Address Event Representation protocol. The instantaneous output spiking frequency is directly proportional to the force applied to the taxel. We show a full characterization of the device as well as quantitative measurements from a prototype fabricated on AMS CMOS 350-nm process. The taxel can reliably distinguish applied forces from 0.1 N up to 1.5 N.