Experimental Characterization of Microfabricated Thermoelectric Energy Harvesters for Smart Sensor and Wearable Applications

Dunham, M.T., Barako, M.T., Cornett, J.E., Gao, Y., Haidar, S., Sun, N., Asheghi, M., Chen, B., Goodson, K.E., 2018, "Experimental Characterization of Microfabricated Thermoelectric Energy Harvesters for Smart Sensor and Wearable Applications," Advanced Materials Technologies, Vol. 28, 1803689.  DOI: 10.1002/admt.201700383.

Download PDF

Microfabricated thermoelectric generators (μTEGs) are excellent candidates for sustainable power delivery for the next generation of smart sensors and wearable devices through harvesting of waste heat. However, the assembly process and inherently small contact areas for thermal and electrical transport introduce losses which can significantly reduce the effective figure of merit ZT. Further, the form factor of μTEGs makes these losses extremely challenging to quantify. The relative contributions of the thermoelectric film and interfaces greatly impact the choice of materials, device geometry, and maximum power point operation. A comprehensive study of μTEG devices including microfabrication, detailed modeling and optimization, and electrical, structural, and thermal characterization of modules and their constituent films is presented. Using a combination of novel infrared microscopy and thin-film characterization techniques, the average thermoelectric material properties and the power output as a function of the true temperature difference across the device are isolated. Power outputs as high as 1 mW for a μTEG with 13.8 mm2 footprint and device ΔT of 7.3 K are measured. An order of magnitude reduction in figure of merit for the devices (ZT ≈ 0.03) compared to the constituent thermoelectric films (zT ≈ 0.3), with implications for the selection of maximum power point operation, is demonstrated.

Related Projects

A key to improving vehicle efficiency is recovering a fraction of the energy lost with the hot exhaust gases, and a promising strategy is to integrate thermoelectric generators with the exhaust...
Interface thermal transport is arguably the leading fundamental challenge for the design and implementation of advanced nanostructure technologies for energy conversion, computation, and data storage...
The most innovative energy conversion technologies, ranging from solar and thermoelectrics to lasers (which convert electric energy to light), are benefitting from nanostructures and/or...