Biodegradable Chitosan-Cellulose Sub-spherical nanocrystals composite piezoelectric thin film with d33 as high as 30 pC/N

Recently, research has increasingly focused on eco-friendly innovations in sensor and actuator technologies, emphasising the importance of using safe, high-performance, environmentally sustainable, flexible and biocompatible materials in biomedical devices. Our study explores the potential of a composite made of cellulose and chitosan, in developing biodegradable piezoelectric ultrasound transducers. As the piezoelectric technology becomes more common in flexible biomedical devices, the need for sustainable alternatives to traditional synthetic and petroleum-based polymers grows more urgent. The developed biodegradable piezoelectric composites offer a chance to create environmentally friendly solutions that are safe for biological tissues and to support a plastic-free future. By integrating sub-spherical piezoelectric cellulose nanocrystals CNCs into a chitosan matrix, we significantly improve the piezoelectric properties of flexible thin films. The resulting chitosan/CNC composite is fully biodegradable and shows a d₃₃ value of 30 pC/N comparable to synthetic polymers like polyvinylidene fluoride (PVDF). This enables these films to be processed to produce effective ultrasound transducers, making them promising for various biomedical applications, including non-invasive imaging and wearable health monitoring. These developments represent a significant step toward sustainable, high-performance piezoelectric devices that fulfil the growing needs of next-generation medical technologies.