A wearable air conditioner? Chinese team creates wristband that could help beat the summer heat

South China Morning Post


14 Apr 2022

Image Credit: Runners blueprint

A Chinese-led research team have developed a fabric that they say can generate power from heat for wearable electronics or help cool people in summer.

The thermoelectric textile, which looks like a wristband and can be twisted, knotted, bent and stretched, can generate power for a device such as a pedometer or LED array, according to the team.

“It feels like a normal wristband when worn on the wrist,” said Zhang Kun, corresponding author of the study and a professor at Donghua University’s school of textiles in Shanghai.

“Textiles can be a good foundation for wearable devices. We can use thermoelectric strings and textiles to make a comfortable thermoelectric generator that can create electricity and adjust the temperature of the body.”

The study was published in the monthly peer-reviewed journal Energy & Environmental Science in Britain last month.

Thermoelectric materials are used in many applications, including in aerospace, infrared detectors and computer chips, with differences in temperature between materials producing an electrical voltage.

Conversely, when a voltage is applied to the material, heat is transferred from one side to the other, creating a cooling effect on one side, a principle at work in heat pumps and some small refrigerators.

American smartwatch development company PowerWatch uses the heat of a wearer to power a watch that the company claims does not need charging and is a world first.

Thermoelectric materials are also expected to be used in industry to capture waste heat to generate electricity.

Zhang and his team looked into how these materials could be combined with textiles.

“Because of temperature differences between the body and the environment, thermoelectric textiles, in theory, can generate power around the clock,” Zhang said.

According to the study, the textile had excellent mechanical and thermoelectric properties, with an output voltage of about 0.28 volts at an outdoor temperature of around 8 degrees Celsius (46.4 degrees Fahrenheit), meaning that it could power small electrical devices.

More importantly, Zhang and his colleagues reported for the first time that they could use the technology to lower body temperatures by several degrees.

Zhang said his team was researching a type of flexible air-conditioned clothing that could lower temperatures by as much as 15 degrees Celsius.

“Summer temperatures in Shanghai can be as high as 45 degrees Celsius. In our experiment last summer, the thermoelectric textile could keep body temperatures at around 35 degrees,” he said.

“When we use air conditioners in summer, one person consumes the same amount of power as 10 people and much of that energy is wasted. If we can control body temperatures, then we can largely reduce power consumption.”