Smart clothing may reduce energy needs for heating, cooling
What if you could wear personalized climate-controlled clothing, thereby reducing the need for heating and air conditioning and the energy costs that come with it? Scientists at the University of California San Diego in the United States are asking that question, and they say they’ve developed a prototype that may make the “smart clothing” a reality.
The soft, stretchy wearable patch is made from thermoelectric alloys made of bismuth and telluride, connected by tiny copper electrodes that use the electricity to create temperature differences. They are layered between two elastomer sheets made of Ecoflex, which contain aluminium nitride powder because the material has a high thermal conductivity. The patch uses the current to transfer heat from one sheet layer to the other.
Developed by nanoengineering professor Sheng Xu and his team, the flexible patch has its own self-powering battery pack and can be embedded in clothing to maintain a constant temperature whether you’re at home, commuting to work, at the office or out with friends.
The research team tested the prototype by creating a mesh armband holding the patch. It cooled the male subject’s skin to 89.6 degrees Fahrenheit within two minutes and kept it at that level as the temperatures in a controlled space where changed in a range between 71.6 and 96.8 Fahrenheit.
“If wearing this device can make you feel comfortable within a wider temperature range, you won’t need to turn down the thermostat as much in the summer or crank up the heat as much in the winter,” said Renkun Chen, whose materials research was published May 17 in the journal Science Advances.
“To do cooling, we have the current pump heat from the skin side to the layer facing outside,” he explained. “To do heating, we just reverse the current so heat pumps in the other direction.”
As one example, Chen said that if a building thermostat was set significantly higher in the summer months, then cooling costs could be reduced by up to 70 percent.
Lead author Sahngki Hong, who completed his doctoral work with Chen, said the idea is to use multiple patches at strategic body points to create clothing that’s more practical than any existing thermal alternatives.
Each square patch has 5-centimeter sides and uses up to 0.2 watts of energy. The researchers think it will take 144 patches to create a cooling vest, for a total of 26 watts needed to stay cool on an average hot day. In extreme heat, that would rise to 80 watts, about the same as a laptop – and far less than standard building air conditioning systems use.
The research team in San Diego, which includes battery and wearables experts as well as the nanoengineers, hopes to take the technology to market in just a few years. In a world of rising temperatures, where climate change is already driving public health and economic concerns over the future of work, the smart clothing may be a breakthrough development with many use cases.
“We’ve solved the fundamental problems, now we’re tackling the big engineering issues—the electronics, hardware, and developing a mobile app to control the temperature,” Chen said.
