Ceramic–polymer capacitive sensors for tactile/force awareness in harsh environment robotic applications

Abstract

The need for force feedback and spatial awareness of contact in harsh environment applications, such as space servicing, has been unsatisfied due to the inability of current sensor technology to resist environmental effects. In this work, capacitive sensors based on a thick film 0:3 connectivity ceramic:polymer composite structure were evaluated for potential use in future operations within robotic end effectors, withstanding temperatures ranging from −80 ° C to 120 ° C and forces up to 350 kPa. A thick film design is utilized to allow for ease of embedding, allowing sensors to be implemented into exciting robotic hardware with minimal intrusion, and protecting sensors from electron bombardment, radiation, and point concentrations from metal-on-metal contact. Taguchi design of experiments allows composition variables including sensor thickness, ceramic composition, ceramic particle size, ceramic volume loading, polymer character, modifier character, and the polymer:modifier ratio to be evaluated simultaneously. Dynamic thermal and mechanical loading techniques were implemented to characterize the composite sensors with in situ electrical acquisition. Individual composition variables were linked to the sensor magnitude, sensitivity, drift, and hysteresis, showing that the sensor response is optimized with a thickness of single microns, 10 vol% loading of nano-particle ceramics, and high molecular weight polymers with a low content of simple architecture modifiers lacking glass or melting temperatures in the working range.