University of Washington Engineers Develop Flexible Thermoelectric Device to Power Wearables

Engineers from the University of Washington have developed a flexible thermoelectric device that can turn wasted heat energy into electricity to power wearable electronics. Unlike current flexible thermoelectric devices designed using inextensible copper electrodes and carbon-based composites, this thermoelectric generator (TEG) is durable for long-term use and can bend, twist and stretch over 15,000 bending cycles at 30% deformity.

“It’s a 100% gain if we harvest thermal energy that would otherwise be wasted to the surroundings. Because we want to use that energy for self-powered electronics, a higher power density is needed,” explains UW assistant professor Mohammad Malakooti. “We leverage additive manufacturing to fabricate stretchable electronics, increase their efficiency and enable their seamless integration into wearables while answering fundamental research questions.”

The team designed the TEG using 3D-printed elastomer composites with engineered functional and structural properties on each layer with filler material that contains liquid metal alloys to provide high electrical and thermal conductivity. It’s those alloys that mitigate the limitations in previous devices, including an inability to stretch, inefficient heat transfer and a complex fabrication process. The device is also outfitted with embedded hollow microspheres to channel the heat to the semiconductors at the core and reduces the weight of the device.

The engineers demonstrated that they could print the TEGs on flexible textiles and curved surfaces without sacrificing energy, suggesting that future devices could be incorporated into clothing and other flexible objects in the near future.