Practical Issues in the Design of Wireless Sensors Supplied by Energy Harvesting Thermoelectric Generators

The use of energy harvesting for supplying wireless sensors becomes a new market opportunity. During last years, new low power transmitters, and also power conversion ICs specifically designed for energy harvesting, have become commercially available. However, as any other power supply circuit, the specific load behavior affects to the power converter, doing that just joining the two parts takes to a nonfunctional device. In this paper, we will measure experimentally the transmitter current of some technologies, for the several sensor states. Some practical issues that affect directly the sensor design will be shown. With this information, some required modifications in the power stage will be proposed. A complete temperature sensor design and assembly is showed. The sensor has been tested in a tandem cold mill, and several experimental results are included.