Sustainable Printed Electrodes for Energy Harvesting from Urine to Power IoT Sensor Nodes in Smart Diapers

The expansion of Internet of Things (IoT) devices is rapidly increasing across various aspects of life, notably in wearable healthcare. With billions of already deployed IoT sensor nodes, this figure is anticipated to escalate into the hundreds of billions in coming years. One of the most significant challenges is how to economically power these devices by adopting sustainable and environment-friendly solutions as the conventional power sources are inadequate to meet the demands of this vast IoT ecosystem. In recent years, innovative approaches have emerged to design energy-optimized electronic systems, opening a pathway for applications based on energy harvesting. In this study, a novel energy harvesting solution is proposed by developing sustainable and disposable harvesting electrodes, leveraging the capabilities of printed electronics technology. These electrodes are engineered to harvest energy from human urine, a readily available resource, to power the energy-efficient wearable IoT sensor nodes of smart diapers. A comprehensive characterization of these harvesting electrodes is conducted using pseudo-urine as an electrolyte within a controlled laboratory environment. The results demonstrate great promise for the development of self-powered IoT sensor nodes of smart diapers, with the capacity for overnight operations lasting up to 12 hours.