Self-powered Sensor Systems Based On Small Temperature Differences: Potential For Building Automation And Structural Health Monitoring

Sensors are the eyes and ears in the service of people - especially in inaccessible areas where regular maintenance or battery replacement is extremely difficult. By using thermoelectric generators, which are capable of directly converting heat flux into electrical energy, self-powered sensor systems can be established wherever temperature differences of a few Kelvin exist. After installation of the sensors, they collect and transmit their data without any need for further maintenance like battery replacement. Intelligent building automation for instance is the key for significant energy reduction in buildings. Through precise control of sun blinds and set temperature for thermostats and air conditioning, radio signal sensors help to increase a building's efficiency massively. Thermoelectric self-powered sensors have the additional potential to introduce more flexibility in the area of building technology as complex wiring is avoided. Buildings can easier be adapted to altered utilization. Structural health monitoring is another field where energy autarkic sensors could be of vital use. In-situ measurements of e.g. temperature, humidity, strain and cracks of buildings are essential in order to determine the condition of construction materials. Respective sensors are hardly accessible, wiring or battery replacement is costly or even impossible. Sensors that are driven by thermoelectric generators are maintenance-free and can help enhancing the longevity of buildings as well as reducing the maintenance costs. Furthermore, leakages in water transport systems can be reduced by in-situ monitoring by self-powered sensors and thus, reduce unnecessary water losses. The large progress in the development of low-power sensors, power management and radio communication combined with the availability of high efficiency thermoelectric generators opens the possibility to run a self-powered sensor node with temperature gradients as low as 0.8K. This potential will be presented with respect to selected fields of application.