Sustainable Sensors Prepared by Environmentally Benign Means for Improving the Environmental Footprint of Wearable Electronics

Abstract

Sustainable electronic devices offer the virtue of energy efficiency. However, their fabrication is often reliant on environmentally deleterious methods and materials that overshadow the environmental benefits the devices provide. Toward improving the overall environmental footprint of devices, stretchable and conductive substrates for enabling wearable electronics are fabricated predominately from both sustainable and biodegradable materials (chitosan and sorbitol) along with an environmental benign solvent: water. Indeed, the >95 wt.% of the stretchable and bendable sensor consists of sustainable and biodegradable materials. By blending a collectively self-doped and water-soluble conductive homopolymer during processing, stretchable films with a transverse resistance as low as 0.08 MΩ are obtained. Both the conductivity and mechanical properties of the films including elongation at break and Young's modulus are contingent on the chitosan molecular weight. The elongation at break of the films prepared from high molecular weight chitosan is upward of 200%, with the optical transmission of 60% above 500 nm, and minimal conductive hysteresis with stretching. Both the mechanical compliance and conductivity of the sustainable films are ideal for enabling wearing electronics. This is demonstrated by their use as strain sensors for tracking both human movement and phonation detection.