From Piezoelectric Nanogenerator to Non-Invasive Medical Sensor: A Review

The document reviews the development and application of Piezoelectric Nanogenerators (PENGs) as non-invasive medical sensors. PENGs convert mechanical energy into electricity and can detect pathophysiological changes. They have been used in various medical sensing applications, including monitoring body fluids, gases, and physiological characteristics. The document discusses the use of different materials in PENGs, such as zinc oxide, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), and barium titanate (BTO), chosen for their flexibility, biosafety, and piezoelectric effect. PENGs have been used in respiratory sensors, cardiovascular monitoring, and wound healing. For instance, a PENG-based sensor was developed for real-time monitoring of blood glucose concentration in human saliva. Despite some limitations, such as vulnerability to environmental influences, PENG-based sensors offer a promising new way to monitor health conditions. The review also suggests future work could focus on improving the energy conversion efficiency and extending the lifetime of the devices.