Inspired by Zebra Stripes, Researchers Solve Size Constraints of TEGs

Taking notes from nature, Gwangju Institute of Science and Technology (GIST) researchers have developed a new thermoelectric generator (TEG) that is flexible, lightweight, and biodegradable. Typical TEG technology normally relies on “out-of-plane” temperature gradients, creating bulky and rigid devices that aren’t suited for many situations. Now, the TEG produced by GIST scientists has the potential to open the doors for new applications for TEGs.

 

The newly-developed device solves many conventional TEG issues, such as size and flexibility, by transforming the TEG to use an in-plane vs. an out-of-plane gradient. Image used courtesy of GIST

 

In order to understand GIST's innovation, this article covers the status quo for TEG design and fabrication and how the GIST design aims to solve some of the most important problems. In addition, we'll discuss the specific operation of the GIST TEG to give readers a sense of how the technology can be improved for use in day-to-day life.

 

A Trio of Effects Driving TEGs

As is so often the case with semiconductor phenomena, thermoelectric devices rely on quantum effects to generate or convert an electric voltage. In this case, three effects provide a background on the operation of TEGs: the Seebeck, Peltier, and Thomson effects.

 

Commercial TEGs leverage three quantum effects and rely on an out-of-plane temperature gradient. Because of this, natural convection can quickly cause the TEG not to function as an effective generator. Image used courtesy of Applied Thermoelectric Solutions

 

While each effect is named after a different person, they all tend to describe the same principle: a temperature difference between two connected metals produces a measurable voltage or current. Conversely, passing a current through a metal-metal junction will produce a temperature gradient. These effects are typically combined with semiconductor technology to realize TEGs.

While traditional TEGs perform well in some applications, they are not all-encompassing. One of the major drawbacks of traditional TEGs is their rigid nature, making them unsuitable for wearable applications. In addition, their use of out-of-plane temperature gradients allows for natural convection to ultimately reduce the effectiveness of the generator.

 

Small-but-effective Generation

To solve the out-of-plane gradient problem, GIST researchers took inspiration from zebra stripes to develop their TEG solution. By carefully applying absorptive and reflective materials, they generated an in-plane temperature gradient that produced electricity.

 

Performance summary of the GIST TEG. The graph shown in G highlights the improved power generation ability of the zebra-inspired TEG. Image used courtesy of Science Advances (Click to enlarge)

 

The flexible, lightweight, and biodegradable nature of the GIST TEG makes it an attractive solution for the next generation of wearables, whereby body heat may be used as a power source to keep the devices charged. In addition, the improved performance of the TEG devices may allow for them to be used as an off-grid renewable energy source, thereby adding a new alternative to renewables.

 

Time to Change Your Stripes

While it’s yet to be seen how effective the GIST TEG may be in a practical application, the improvements in power generation are certainly a step in the right direction for self-charging wearables. In addition, GIST researchers have targeted personal climate control as a potential application, further solidifying the potential for the zebra-inspired TEG to become a critical component in smart wearables.

Regardless of the niche in which it finds itself, the GIST TEG seems to support a bevy of qualities that will make it ripe for future research and development. Previous trends for TEGs in wearable electronics indicate that this research brings us one big step closer to an efficient and practical wearable power solution.