Corrugated Compliant Capacitor towards Smart Bandage Application

Abstract

The focus of this study is to characterize a soft elastomeric capacitor (SEC) capable of monitoring large levels of deformation towards smart bandage applications. The SEC is a highly compliant, low cost, and scalable strain gauge, designed to transduce strain into a measurable change in capacitance. Early work on the SEC was conducted on untextured versions, where the dielectric was sandwiched between two flat electrodes. It has been shown that the use of currugated surfaces significantly improves the sensor's sensitivity, linearity, and resolution, and that the sensor could be used to effectively monitor elongation in intact (i.e., unwounded) canine skin. In this paper, work on the SEC technology is extended to evaluate the use of corrugated SEC as a smart bandage capable of monitoring strain and reducing stresses on soft tissue. A series of experimental tests is conducted on two corrugated patterns, namely a reentrant hexagonal honeycomb pattern (auxetic pattern) and a symmetric diagonal grid pattern, to further characterize the signal of the corrugated sensor under various levels of localized strain resembling an opening wound. After, prior numerical investigations on canine skin are extended to study opportunities in leveraging corrugation to improve stress distribution around a wound. Results show that corrugation significantly improves both the signal and stress distribution onto soft tissue, with the auxetic pattern exhibiting best performance, therefore demonstrating the promise of the corrugated SEC as a smart bandage.