Folding and stretching a thermoelectric generator

As we are at the verge of entering the era of Internet-of-Things (IoT), there is a clear need to produce continuous power supply to the huge amount of electronic devices that must be wirelessly interconnected and operate uninterruptedly. At the same time, new mechanical constrains arise from the fact that these devices should be ubiquitous, which leads to the need of lightweight and mechanical compliance to any shape or surface. As an important renewable energy source, a mechanically adaptable thermoelectric generator (TEG) can make use of the usually wasted thermal differences between ambient and technology-users to power-up such systems. With this idea in mind, we have developed a simple approach to fabricate TEGs, based on commonly available substrates (paper or polymers) and assisted through simple folding and cutting techniques (born from origami and kirigami) to form strategic structures (serpentine, helical, spiral, etc.) with the mechanical advantage of foldability and over 100% demonstrated stretchability. The use of these methods and structures allows the mechanical reconfigurability of the devices to, for example, increase the temperature difference in a TEG, thus its power, or allow a more efficient use of area and therefore increase the power density. We will discuss the strategies to effectively integrate folding and cutting techniques with common materials and the basic TEG configuration, as well as demonstrate the devices' implementation and characterization. Finally, we believe our simple integration approach offers an interesting and versatile methodology, which can be easily extrapolated to new materials and technologies for a greater variety of applications.