Robust polymer-HfO ₂ thin film laminar composites for tactile sensing applications

Abstract

Abstract A method for high resolution tactile sensing for robotic end-effectors used in variable environmental conditions is required for practical robotic applications, such as heavy industry, construction, military and space applications. In this work, a robust, flexible tactile sensor based on a capacitive sensing mechanism with high sensitivity and stability that can operate between −60 °C and 120 °C was developed. The active sensing thick film was composed of a 2:2 connective polymer-ceramic laminar composite. A stress-sensitive elastomer (Arathane 5753 A/B) was used as the primary compliant layer within the laminar architecture, and a HfO 2 thin film was used as the dominating dielectric layer to improve the sensitivity of the sensor. The sensors were fabricated on a flexible polyimide film (Kapton) to conform to the end-effector geometry. The fabricated sensor showed good sensitivity and cycle stability (between 0 and 360 kPa). The capacitance change due to temperature variations were studied in detail. Three different capacitive sensor architectures were developed to study the influence of the HfO 2 layer on the sensitivity of the sensor. Thermomechanical loading cycles were performed with in situ electrical acquisition to characterize the sensor. Chemical and structural characterization of the HfO 2 layer deposited on a flexible substrate was implemented using conductive atomic force microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy, and the optical properties were analyzed by the ultra-violet visible spectrophotometer.