Body heat could power Google Glass and other wearables

As the attention turns towards wearable devices like Google Glass and smart watches, how to ensure power supply in a stable and reliable manner is one of the most critical issues facing the developers.

What about a light, tiny generator that can produce electricity from the heat emanating from the human body?

Possible.

A team of researchers have proposed a solution to this problem by developing a glass fabric-based thermoelectric (TE) generator that is extremely light and flexible and produces electricity from the heat of the human body.

In fact, 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," claimed Byung Jin Cho, a professor of electrical engineering at KAIST (formerly also known as Korea Advanced Institute of Science and Technology) in South Korea.

The team came up with a new concept and design technique to build a flexible TE generator that minimises thermal energy loss but maximises power output.

"The TE generator has a self-sustaining structure, eliminating thick external substrates (usually made of ceramic or alumina) that hold inorganic TE materials," Cho explained.

Till date, two types of TE generators have been developed based either on organic or inorganic materials.

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 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," Cho noted.

This flexible, light and high-performance TE generator has further applications in scale-up systems such as automobiles, factories, aircrafts, and vessels where we see abundant thermal energy being wasted, the researchers concluded in a paper published in the journal Energy & Environmental Science.