Sustainable, Flexible, and Biocompatible Enhanced Piezoelectric Chitosan Thin Film for Compliant Piezosensors for Human Health

The necessity to continuously and seamlessly monitor human health is calling for compliant, comfortable, and safe wearables. The employment of piezoelectric biopolymers in form of thin film perfectly matches with these needs due to their inherent flexibility, sensitivity, and biocompatibility. Among them, chitosan is a low cost, highly sustainable, and biocompatible material with a great potential for applications in compliant wearables. However, chitosan and biopolymers in general show relatively low piezoelectric coefficients and processing difficulties. Here, it is shown a facile approach to increase more than twice the piezoelectric coefficient of thin chitosan film and to process this promising biomaterial for the fabrication of the first set of thin chitosan film-based ultrasound transducers. This work leverages the exploitation of environmental-friendly biopolymers in the development of compliant wearable transducers and thus represents a step forward in the development of completely biodegradable, transparent, thin, and flexible piezoelectric macro- and microtransducers.