SUSTEG · Sustainable Thermoelectric Generators for Low-Power Applications

The Internet of Things (IoT), where everyday objects sense their environment and communicate with each other, is a key drive of digitalization expected to make our society safer, more sustainable, and more competitive. The full deployment of the IoT requires sustainable and long-lasting energy solutions to minimize e-waste. Thermoelectrics (TEs) can convert the ubiquitous waste heat into electricity and could complement or even replace batteries to meet the renewable energy needs of IoT nodes. However, commercially available TEs are expensive, rely on raw critical materials, and present a limiting form factor (small, rigid, and flat) preventing their application on curved and dynamic surfaces. This research proposes the development of cost-effective and sustainable flexible TEs to power IoT devices. The devices will involve exclusively environmentally friendly materials, namely conducting polymers dissolved in non-toxic solvents, along with a compostable substrate to minimize e-waste. Fabrication will be carried out using brush and inkjet printing, performed at ambient conditions and temperatures below 150 °C. The process flow will be limited to 5-6 simple steps, avoiding post-treatment with harmful chemicals or energy-intensive procedures. Despite their minimalistic processing, the devices performance will be comparable to the state-of-the-art organic TE generators. They will generate a ~ 100 nW/cm^2 from a temperature difference of 20 K, a condition easily met in daily life scenarios such as contact with a wall heater, proximity to a motor, or mounted on human or pets skin. This power density over surface areas of a few cm^2 is sufficient to operate low-power IoT edge devices like low-sense rate accelerometers, pacemakers, RFID tags, thermometers, or light sensors.