Autonomous sensor system with RF link and thermoelectric generator for power harvesting

Autonomous sensing system is a promising approach in applications that do not allow cabled solutions and the use of battery has maintenance problems. In this paper an autonomous sensor system with low power electronics for RF communication and with an energy harvesting module is presented. The sensored system is proposed for temperature measurements, but it can be used with other sensor types to measure different quantities. When the autonomous sensor is placed on a heat source, a thermoelectric module harvests energy, powering the autonomous sensor. In this condition no external electromagnetic field is necessary, the temperature measurement is performed and the data are saved in non-volatile memory. When the readout unit is active the electromagnetic field is used to power the autonomous sensor system and to communicate the data. An experimental set-up has been arranged to compare the temperature data of the heat source collected by the autonomous sensor and a referenced thermoresistance. The experimental measurements shows good agree between the two measured temperature data. The wake-up signals demonstrate that the autonomous system works correctly for a temperature gradient of less than 9degC, and with a readout distance of few centimeters. The presented autonomous sensor system can be efficiently used for measurements into close environment in which a temperature difference is present.