Chitosan film based piezoelectric nanogenerator for ambient energy harvesting.

Herein, we report a flexible chitosan-based piezoelectric nanogenerator (CPENG) fabricated using a simple and scalable solution-casting method from commercially available chitosan, an abundant and environmentally friendly biopolymer. The CPENG efficiently converts low-frequency mechanical stimuli into electrical energy through the piezoelectric response of the chitosan matrix. Under repeated finger tapping, the device produces an open-circuit voltage of ~ 18 V and a short-circuit current of ~ 1.0 µA. The device also shows good signal reproducibility and stable performance under repeated mechanical deformation. Furthermore, the CPENG can harvest energy from different ambient mechanical stimuli, producing electrical responses of ~ 1.6 V under finger touch, ~ 1.2-1.5 V under mechanical vibrations induced by human body movement, and ~ 200-380 mV under airflow. The practical energy-harvesting capability of the device is demonstrated by charging a 1 µF capacitor to ~ 2.3 V within 20 s and powering 13 light-emitting diodes without an external power source. The combination of flexibility, biodegradability, simple fabrication, and effective energy conversion highlights the potential of chitosan-based piezoelectric nanogenerators for sustainable energy harvesting, wearable electronics, and self-powered sensing applications.