A group of Korean researchers have created a flexible, lightweight power solution for wearable devices in the form of a wristband. This small device uses the body’s own heat to produce energy to power devices with an output power density that is several tens of times higher than any other flexible thermoelectric generator to date, while still taking up little space, weighing very little, and exhibiting impressive flexibility. From Phys.org:
The concept and design technique involves building a thermoelectric (TE) generator that minimizes thermal energy loss. The release pointed out that thermo-elements are not new. To date two types of TE generators have been developed.
“The organic-based TE generators use polymers that are highly flexible and compatible with human skin, ideal for wearable electronics. The polymers, however, have a low power output. Inorganic-based TE generators produce a high electrical energy, but they are heavy, rigid, and bulky.”
The distinguishing feature of the KAIST team’s device is that their thermo-element is lightweight, high in electric power production efficiency, and is made with glass fiber. Said Prof. Cho: “The glass fabric itself serves as the upper and lower substrates of a TE generator, keeping the inorganic TE materials in between. This is quite a revolutionary approach to design a generator. In so doing, we were able to significantly reduce the weight of our generator (~0.13g/cm2), which is an essential element for wearable electronics.”
The KAIST team’s thermoelectric generator can be bent as many as 120 times, it was reported, but still showing high performance. The release noted its flexibility: “It is so flexible that the allowable bending radius of the generator is as low as 20 mm. There are no changes in performance even if the generator bends upward and downward for up to 120 cycles.”