New harvester for organic thermoelectric generators

Nowadays, with the incipient growth of the internet of things (IoT) and its applications, like wearable devices or wireless sensor networks (WSNs), the need for portable, robust and sustainable power sources that allow devices to work without external energy sources arises.

Power consumption is a critical problem on these devices, limiting the device lifetime or forcing an increase in the battery size. In these cases, generators based on energy harvesting can extend the life of these batteries, or maybe replace them in certain cases.

However, energy harvesters based on thermoelectric generators have some drawbacks that have to be addressed, like low output voltages or low output power for devices with small areas. Hence, if these generators are used to supply conventional electronics, which may use voltages around 1.8 V, a power management stage is needed to extract the maximum possible power and step up the voltage obtained from the generator.

In this regard, my ESR project consists on designing this power management stage, as well as a low-power electronics control unit (ECU) to manage different sensors supplied by organic thermoelectric generators (OTEGs) designed by HORATES members, as a proof-of-concept for them. This ECU must be developed over a flexible substrate, using hybrid (silicon and printed) electronics.

Since starting at Eurecat, I helped design an ECU over a rigid substrate (FR4) to manage CO₂, humidity, temperature and O₃ sensors, and currently, I’m designing an RF-based harvester, used to supply smart labels, but fabricated over Kapton®/copper. In the future, this new harvester will be translated to a PET substrate, using conductive silver ink for the traces.

Furthermore, the goal of this work is not only to provide a proof-of-concept for the OTEGs, but to generate design rules for low-power printed electronic circuits future designs as well.