Fully biodegradable piezoelectric nanogenerator based on cellulose/PLLA electrospun fibers with high-performance for mechanical energy harvesting

Research efforts are intensifying to employ fully biodegradable piezoelectric nanogenerators (PENGs) as self-powered medical implanted devices and health monitoring products. Poly(L-lactic acid) (PLLA) shows significant promise for biological applications owing to its natural biodegradability, particularly when fabricated as nanofibrous structures via electrospinning. However, PLLA faces inherent limitations related to its relatively weak piezoelectric properties, specifically characterized by a low shear piezoelectric coefficient (d₁₄), which is the familiar form. In this study, a fully biodegradable PLLA nanofiber incorporated with cellulose was applied as piezoelectric film by electrospinning approach. Cellulose/PLLA film exhibits remarkable enhancements in piezoelectric performance, showcasing a 1.6-fold increase in the longitudinal piezoelectric coefficient (d₃₃∼64.2 pm/V) and a substantial boost of nearly 250 % in output voltage. Soil burial experiments conducted over a period of 120 days validate the film's superior biodegradability, with a degradation rate exceeding 93.6 %. Furthermore, the optimized cellulose/PLLA fiber-based PENG demonstrates a maximum open-circuit voltage of 10.3 V and robust mechanical stability, enduring 30,000 cycles without degradation. Notably, the cellulose/PLLA nanofiber-based piezoelectric sensor exhibits efficient detection capabilities, evidenced by distinct output signals in response to varying airflow pressures. Taking into account the advantages of facile fabrication and the utilization of readily available sustainable materials, the proposed cellulose/PLLA device presents a promising eco-conscious alternative for self-powered electronic skin and implantable medical applications.