Investigation of Biodegradable Metals for Green and Sustainable Temperature Sensors

The management of electronics waste and the development of sustainable end-of-life strategies are key aspects of the green evolution of the electronics industry. To address this global issue, we implemented thin-film resistance temperature detectors (RTDs) using green sensing metals, such as Mg, Mo, and Zn, and poly-ether ether ketone (PEEK), as a biocompatible, flexible, and thermally resistant substrate. The environmentally friendly RTDs were characterized in a range of temperature, from 25 °C to 70 °C, showing consistent response and average sensitivities of 1.1\times 10^{-1} %/°C, 7\times 10^{-2} %/°C, and 5.8\times 10^{-2} %/°C for Mg, Mo, and Zn, respectively. At a constant temperature 25 °C, the effect of humidity variation from 10% to 90% on the resistance of the sensors was observed to be 2.0\times 10^{-5} %/relative humidity (RH), 3.4\times 10^{-2} %/RH, and 5\times 10^{-3} %/RH, respectively, for Mg, Mo, and Zn RTDs. Furthermore, the sensor's response to mechanical strain was evaluated by bending the devices down to a 10-mm bending radius. In addition, the dissolution of the green RTDs in water allows the reusability of the substrate for a new fabrication batch, minimizing the amount of electronics waste generated. Through this study, a promising solution to environmental concerns, realizing is endowed for realizing temperature sensors, with applications in green and sustainable wearable systems is demonstrated.