October 1, 2022
  • October 1, 2022

Flexible device harnesses thermal energy to power portable devices

By on August 2, 2022 0
Wearable electronics, from health and fitness trackers to virtual reality headsets, are part of our daily lives. But finding ways to continuously power these devices is a challenge. University of Washington Researchers have developed an innovative solution: the first flexible and portable thermoelectric device that converts body heat into electricity. This device is soft and stretchy, yet sturdy and efficient – properties that can be difficult to combine.
“It’s a 100% gain if we harvest thermal energy that would otherwise be wasted in the environment. Because we want to use this energy for self-powered electronics, higher power density is needed” , said Mohammad Malakooti, ​​a U.W. assistant professor of mechanical engineering. “We are leveraging additive manufacturing to fabricate scalable electronic components, increase their efficiency, and enable their seamless integration into wearable devices while answering fundamental research questions.”
Even after more than 15,000 stretch cycles at 30% strain, the researchers’ prototype device remains fully functional, a highly desirable feature for wearable electronics and soft robotics. The device also shows a 6.5 times increase in power density over previous expandable thermoelectric generators. For more information, see the IDTechEx report on Recovery of thermoelectric energy and other zero-emission electricity from heat 2022-2042.

To create these flexible devices, researchers 3D printed composites with engineered functional and structural properties at each layer. The filler material contained liquid metal alloys, which provide high electrical and thermal conductivity. These alloys address the limitations of previous devices, including an inability to stretch, inefficient heat transfer, and a complex manufacturing process. The team also incorporated hollow microspheres to direct heat to the semiconductors at the core layer and reduce the weight of the device.

The researchers showed that they could print these devices on stretchable textile fabrics and curved surfaces, suggesting that future devices could be applied to clothing and other objects. The team is excited about the future possibilities and real world applications of wearable electronics.

“A unique aspect of our research is that it spans the entire spectrum, from materials synthesis to device fabrication and characterization,” said Malakooti, ​​who is also a research fellow at UW’s Institute of Nano-Engineering Systems. “It gives us the freedom to design new materials, design every step of the process, and be creative.”

Source and top image: University of Washington