Metal-based folded-thermopile for 2.5D micro-thermoelectric generators

To help you access and share this work, we have created a Share Link – a personalized URL providing 50 days' free access to your article. Anyone clicking on this link before February 08, 2023 will be taken directly to the final version on ScienceDirect, which they are welcome to read or download. No sign up, registration or fees are required.Your personalized Share Link: https://authors.elsevier.com/a/1gHfL3IC9dBKJP; International audience; We report on the simulation and fabrication of 2.5D micro-thermoelectric generators (µTEGs) with a thermopile topology periodically folded and distributed on a multi-membrane template, capable of harvesting lost heat directly into useful electrical energy. The originality of the folded thermopile is multiple: i/ it uses low-cost and eco-friendly alloy-based thermoelectrics (TEs) in the form of a series of Ni90Cr10/Cu55Ni45 thermocouples (TCs), ii/ in each TC both TE layers are stacked on top of each other allowing a better integration, iii/ the TCs are electrically associated in series and in parallel, reducing drastically the electrical resistance, iv/ the choice of membrane number permits to tune the module thermal resistance. All this results in an improvement of the conversion efficiency of the µTEG compared to our former all-Silicon planar modules. A finite element simulation allows defining the temperature distribution profiles in the module as a function of its dimensions. Several 2- and 3-membranes based µTEGs were fabricated using CMOS-compatible Silicon technology and characterized. In the best µTEG, the harvesting of 1 Watt of heat results in an output power density of 108.3 µW/cm2. This corresponds to an efficiency factor of 6.82 10-3 µW.cm-².K-² which is better than state-of-the-art metal-based modules.