A team of engineers at the University of San Diego has developed a wearable "patch" that provides personal 'air conditioning' by heating or cooling the body and keeping it at a constant temperature in all weather conditions.
The project was published yesterday in the magazine Science Advances.
In addition to providing comfort to the wearer, such a device has many prospects of use in terms of energy sustainability and savings: "With a constant and comfortable body temperature there is no longer the need to activate air conditioners," says Renkun Chen, the professor of mechanics e aerospace engineering who conducted the study.
There is a huge variety of stand alone heating or cooling systems to take with you. Table and floor fans, heaters, but no one before today was wearable, flexible and easily integrated into clothes.
The patch is made of thermoelectric materials inserted as in a sandwich between two layers of elastomers made with Ecoflex, a soft material based on powdered aluminum nitride, which has great electrical conductivity. The device heats up or cools down to the temperature chosen by the wearer.
It can be placed in areas of the body that have faster thermal variations than others: the back, neck, feet or hands, to get relief from the cold or heat.
Sahngki Hong, co-author of the project.
The tests
The researchers integrated a prototype of the 'heat patch' into an elastic bracelet and tested it on a volunteer in a controlled temperature environment. In just 2 minutes the device brought the subject's body temperature to 32 ° C, keeping it constant while the surrounding environment varied from 22 to 36 degrees.
The vanguard of a smart suit
The ultimate goal of the project is to combine multiple parts of this 'patch' to create a smart suit that can regulate the wearer's temperature: a device that can be ironed and squeezed without compromising its electronic functions.
The mechanism
To warm up or cool down, the patch uses a weak electric current that moves heat from one elastomer 'sheet' to another in this sort of sandwich: in this way the side in contact with the skin becomes hot and the outer one cold, or vice versa. .
The power supply is given by a thin and flexible battery of cells connected by very thin copper springs that give flexibility to the whole apparatus.
Energy saving
Each patch is a 5cm square and consumes 0.2 watts of energy. Chen's team estimates that 144 patches are needed to create an 'air-conditioned' garment, which consumes 26 to 80 watts (on particularly extreme days) to keep the wearer's body temperature constant and comfortable. For comparison, an air conditioner consumes tens of kilowatts.
Air conditioning each individual has greater efficiency and greater savings than air conditioning large rooms. In fact, with current air conditioning systems, keeping an office temperature constant means consuming thousands of watts per person. Such a device significantly reduces energy consumption and environmental impact.
The team is currently working on the development of the entire dress, and hopes to commercialize it in a few years: the problems now are related to the production system and ... the smartphone app that will control the heat of your body!
I study: "Wearable thermoelectrics for personalized thermoregulation" su Science Advances (2019)
