Persistent, single-polarity energy harvesting from ambient thermal fluctuations using a thermal resonance device with thermal diodes

There is a pressing need for durable energy harvesting techniques that are not limited by intermittency, and capable of persistent and continuous operation in a variety of environments. Our laboratory has previously identified ambient thermal fluctuations as potentially abundant, ubiquitous sources of such energy. In this work, we present a mathematical theory for the operation and design of a thermal resonator interfaced with optimized thermal diodes on its external boundaries with the environment. We show that such a configuration is potentially able to produce single polarity temperature difference drastically exceeding that of previously reported thermal resonators by a factor of 5. We further introduce an experimental testbed of mechanical thermal switches capable of mimicking thermal diodes with a possibility to tune thermal rectification in a broad range. The testbed allows us to identify additional design rules for our system dictated by material properties. Lastly, our theory establishes a generic performance metrics over thermal diodes available in the literature. The established framework will help to design novel thermal elements, build efficient thermal harvesting systems, and compose nonlinear thermal circuits. ; The authors acknowledge the Office of Naval Research (ONR), under award N00014-16-1-2144, and King Abdullah University of Science and Technology (KAUST), under award OSR-2015-Sensors-2700, for their financial support regarding this project. The authors also acknowledge Gerald Hughes and Justin Raymond at MIT for their help with temperature data collection on MIT's campus. Lastly, we acknowledge Mark Derome at MIT Haystack Observatory for his help collecting the drone flight data. Correspondence and requests for materials should be addressed to M.S.S.