Scientists at the Harbin Institute of Technology, Shenzhen (in China), have developed a small, flexible device capable of converting the heat emitted by human skin into electrical energy . In their research, the team showed that the device was capable of turning on an LED light in real time when worn on a bracelet.
The device consists of a thermoelectric generator (TEG) that uses temperature gradients for power generation.
Specifically, in this design, the scientists, whose research has been published in the journal ‘Cell Reports Physical Science’, use the difference between the warmest body temperature and the relatively colder environmental environment to generate energy.
According to the experts, we would be facing a field with great potential, since thermoelectric generators could recover the energy that is lost as waste heat and, with it, improve the rate of energy use .
Unlike what happens with traditional generators, which tend to use the energy of movement for energy production, in the case of TEGs they do not have moving parts, which makes them essentially free of any type of maintenance. These generators are installed in machines located in remote areas, and we often find them in space probes for power supply.
Scientists have been working for years on the design of thermoelectric generators. But, with wearable devices (like fitness trackers) becoming increasingly popular, the team wanted to explore whether TEGs could replace the battery traditionally present in these devices, including biosensors, smart watches, and fitness trackers .
However, during the development of the research they encountered a problem: traditional thermoelectric generators are usually rigid and can withstand little bending. To overcome this limitation, by making the device more adaptable to smartwatches, the scientists attached the core electrical components to a much more adhesive, stretchable polyurethane material .
In turn, the new design avoids the use of bismuth, a rare type of metal that does not tend to occur naturally in large quantities, being partially replaced with a magnesium-based material , being very useful in reducing the substantially the cost of large-scale production.
Finally, the researchers designed a prototype of a self-powered electronic system , connecting an LED to a TEG band 11.50 centimeters long and 2.80 centimeters wide, and wrapping the TEG band around the wrist of a person whose body temperature measured 34 ºC under ambient conditions.
With a difference in temperature, the generator was able to collect the heat emitted by the skin and successfully turned on the LED strip .
As scientists agree, the prototype presented would already have a good performance if it is introduced on the market at this time. So it would only be enough to add the appropriate voltage converter so that the system could power common portable electronic devices, such as pulse sensors or smart watches.
Looking to the not-too-distant future, scholars plan to improve the design so that the device can absorb heat even more efficiently. So when you consider that there is a growing demand for greener energy, and thermoelectric generators fit the bill, they could convert wasted heat into energy.
Furthermore, unlike solar energy (which can only be produced when there is sun), TEGs can produce energy in practically any setting, as long as there is a difference in temperature .
