Melamine-Derived Carbon Nitride-Functionalized Polyurethane Nanomesh-Based Triboelectric Nanogenerator for Self-Powered Respiration Monitoring

Herein, a highly sensitive self-powered wearable pressure sensor (SPWPS) for ultra-low pressure respiration monitoring is proposed, based on a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{g}-\mathrm{C}_{3}\mathrm{N}_{4}$</tex> -functionalized polyurethane (PU) nanomesh serving as a highly positive triboelectric layer. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{g}-\mathrm{C}_{3}\mathrm{N}_{4}$</tex> incorporation in PU resulted in an enhancement in capacitance and charge accumulation through the synergistic effects between the semiconductive fillers and the polymer, leading to improved charge density in the nanocomposite. Moreover, the large internal surface area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{g}-\mathrm{C}_{3}\mathrm{N}_{4}$</tex> further amplifies the charge-donating capability while minimizing dielectric loss. The developed self-powered, tympanic membrane-inspired wearable pressure sensor exhibited a sensitivity of 0.5150 V/kPa within a low-pressure range of 0.3 to 1.7 kPa and a power density of 2.89 Wm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup>. The sensor was successfully demonstrated as a real-time, non-invasive, wearable diagnostic approach for monitoring breathing patterns and inhalation-exhalation activities via smartphone applications.