Distributed Tactile Sensors for Palmar Surfaces of Prosthetic Hands

Abstract

Sensory feedback provided by prosthetic hands shows promise in increasing functional abilities and promoting embodiment of the prosthetic device. However, sensory feedback is limited based on where sensors are placed on the prosthetic device and has mainly focused on sensorizing the fingertips. Here we describe distributed tactile sensors for the palmar surfaces of prosthetic hands. We believe a sensing system that can detect interactions across the palmar surfaces in addition to the fingertips will further improve the experience for the prosthetic user and may increase embodiment of the device as well. This work details the design of a compliant distributed sensor which consists of PiezoResistive and PiezoElectric layers to produce a robust force measurement of both static and dynamic loads. This assembled sensor system is easy to customize to cover different areas of the prosthetic hand, simple to scale up, and flexible to different fabrication form-factors. The experimental results detail a load estimation accuracy of 95.4% and sensor response time of less than 200ms. Cycle tests of each sensor shows a drifting of within 10% of sensing capability under load and 6.37% in a no-load longitudinal test. These validation experiments reinforce the ability of the DualPiezo structure to provide a valuable sensor design for the palmar surfaces of prosthetic hands.