Novel Thermoelectric Energy Harvesting Circuit for Exploiting Small Variable Temperature Gradients Based on a Commercially Available Integrated Circuit

Nowadays there is an increasing demand in generating electrical power out of ambient sources, such as light, wireless power, vibrations or heat, to supply low power electronics of self-sustaining sensor nodes. The main problem is that if dealing in harsh environments, or at places with very little energy budgets and additional varying environmental conditions, sophisticated harvesting circuits are necessary. In this work a novel approach for such a circuit is described that deals with thermal gradients. It bases on a commercially available integrated circuit, but with an external wiring scheme, according to the presented modified block diagram of a general harvesting system. A detailed description is given how to analyze the energy requirements. Additionally, the importance of adequate matching of the thermo-electric generator to the input impedance of the circuit is pointed out and at last the wiring of external components to override the internally fixed switching scheme of the build in blocks of the integrated circuit is described. Measurements verify the function of the low power thermal energy harvesting unit and demonstrate in detail the solutions to the key challenges to exploit maximal power out of thermal gradients and to supply a sensor node electronics over a certain time.