Wearable electret based metal oxide nanostructure for self-powered respiration monitoring

Abstract

Exhaled human breath contains information regarding metabolic and physiological data, and its monitoring can play a crucial role in the early clinical diagnosis and treatment of diseases. An energy-autonomous breath monitoring device was designed by anodizing Al sheet (Nose Bridge), present in existing commercial, medical, and industrial masks for monitoring breath. The electrochemically grown porous anodic alumina (PAA) film acts as the electret layer for generating and trapping charge carriers and has the dual function of energy harvesting and sensing. The device is based on the principle of a triboelectric nanogenerator (TENG), where PAA and Polydimethylsiloxane (PDMS) were used as tribo-electrodes, generating a peak-to-peak voltage of 225 V and a short circuit current of 1 μA with a power density of 110.75 mW/m2. PAA with small pore diameter, depth, and long-range ordering exhibit the best performance. The nanoporous structure of PAA provides an exceptionally high surface area of 14.31 m2/g, significantly enhancing the performance. The device exhibits an exceptionally high sensitivity of −15.84/RH% in the 25–90 RH% detection range, with a hysteresis of 2.2% at 65 RH%. This research paves the way for developing personalized healthcare monitoring systems by integrating anodized nose bridges in medical and industrial masks that provide mechanical support and can be used for energy harvesting and breath monitoring.