A Completely Autonomous TEG-Based Node for Thermal Gradient Measurements

This paper presents a fully autonomous measurement system based on thermoelectric generators (TEGs). The system implements a battery-less device that, by using a TEG, harvests energy from a thermal gradient and it is able to perform measurements with the same transducer. The device implements a conditioning circuit to harvest energy using an ultra-low-power system on chip (SoC) provided by STMicroelectronics. The SoC plays the role of sensing the harvested energy to activate a Bluetooth Low Energy radio as soon as the harvested energy is enough for transmission. The measuring method exploits the proportionality between the thermal gradient and the frequency of the transmitted beacons. The reading of the measurement data uses a convenient time-domain readout approach. Results and experiments evince the suitability of the proposed solution with the possibility to adopt and disseminate the device in various environments and for application in an industrial scenario.