Wearable cooling and heating patch could serve as personal thermostat and save energy

Wearable cooling and heating patch could serve as personal thermostat and save energy
Prototype of the cooling and heating patch embedded in a mesh armband. Credit: David Baillot/UC San Diego Jacobs School of Engineering

Engineers at the University of California San Diego have developed a wearable patch that could provide personalized cooling and heating at home, work, or on the go. The soft, stretchy patch cools or warms a user's skin to a comfortable temperature and keeps it there as the ambient temperature changes. It is powered by a flexible, stretchable battery pack and can be embedded in clothing. Researchers say wearing it could help save energy on air conditioning and heating.

The work is published May 17 in the journal Science Advances.

"This type of device can improve your personal thermal comfort whether you are commuting on a hot day or feeling too cold in your office," said Renkun Chen, a professor of mechanical and at UC San Diego who led the study.

The device, which is at the proof-of-concept stage, could also . "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," Chen said. Keeping a building's set temperature 12 degrees higher during the summer, for example, could cut cooling costs by about 70 percent, he noted.

There are a variety of personal cooling and heating devices on the market, but they are not the most convenient to wear or carry around. Some use a fan, and some need to be soaked or filled with fluid such as water.

Chen and a team of researchers at the UC San Diego Jacobs School of Engineering designed their device to be comfortable and convenient to wear. It's flexible, lightweight and can be easily integrated into clothing.

Wearable cooling and heating patch could serve as personal thermostat and save energy
Armband embedded with flexible battery pack (left), stretchable circuit (center), and cooling/heating patch (right). Credit: David Baillot/UC San Diego Jacobs School of Engineering

The patch is made of thermoelectric alloys—materials that use electricity to create a temperature difference and vice versa—sandwiched between stretchy elastomer sheets. The device physically cools or heats the skin to a temperature that the wearer chooses.

"You could place this on spots that tend to warm up or cool down faster than the rest of the body, such as the back, neck, feet or arms, in order to stay comfortable when it gets too hot or cold," said first author Sahngki Hong, a UC San Diego mechanical engineering alumnus who worked on the project as a Ph.D. student in Chen's lab.

The researchers embedded a prototype of the patch into a mesh armband and tested it on a male subject. Tests were performed in a temperature-controlled environment. In two minutes, the patch cooled the tester's skin to a set temperature of 89.6 degrees Fahrenheit. It kept the tester's skin at that temperature as the ambient temperature was varied between 71.6 and 96.8 degrees Fahrenheit.

A building block for smart clothing

The ultimate goal is to combine multiple patches together to create smart clothing that can be worn for personalized cooling and heating. So engineers designed a soft electronic patch that can stretch, bend and twist without compromising its electronic function.

The work is a collaboration between several research groups at the UC San Diego Jacobs School of Engineering. Chen's lab, which specializes in heat transfer technology, led the study. They teamed up with nanoengineering professors Sheng Xu, an expert in stretchable electronics, Shirley Meng, an expert in battery technology, Ping Liu, who is also a battery expert, and Joseph Wang, a wearable sensors expert.

Wearable cooling and heating patch could serve as personal thermostat and save energy
Flexible, stretchable cooling and heating patch. Credit: David Baillot/UC San Diego Jacobs School of Engineering

The researchers built the patch by taking small pillars of thermoelectric materials (made of bismuth telluride alloys), soldering them to thin copper electrode strips, and sandwiching them between two elastomer sheets.

The sheets are specially engineered to conduct heat while being soft and stretchy. Researchers created the sheets by mixing a rubber material called Ecoflex with aluminum nitride powder, a material with .

The patch uses an to move heat from one elastomer sheet to the other. As the current flows across the bismuth telluride pillars, it drives heat along with it, causing one side of the patch to heat up and the other to cool down.

"To do cooling, we have the current pump heat from the skin side to the layer facing outside," Chen explained. "To do heating, we just reverse the current so heat pumps in the other direction."

The patch is powered by a flexible battery pack. It is made of an array of coin cells all connected by spring-shaped copper wires and embedded in a stretchable material.

Wearable cooling and heating patch could serve as personal thermostat and save energy
Cooling/heating patch. Credit: David Baillot/UC San Diego Jacobs School of Engineering

Saving energy

One patch measures 5 × 5 centimeters in size and uses up to 0.2 watts worth of power. Chen's team estimates that it would take 144 patches to create a cooling vest. This would use about 26 watts total to keep an individual cool on an average hot day (during extreme heat, estimated power use would climb up to 80 watts, which is about how much a laptop uses). By comparison, a conventional air conditioning system uses tens of kilowatts to cool down an entire office.

It's more energy-efficient to cool down an individual person than a large room, researchers noted. "If there are just a handful of occupants in that room, you are essentially consuming thousands of watts per person for cooling. A device like the could drastically cut down on cooling bills," Chen said.

The team is now working on patches that could be built into a prototype cooling and heating vest. They hope to commercialize the technology in a few years.

"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 ," Chen said.


Explore further

Clothing made from a reversible fabric could warm or cool wearers and keep them comfortable

More information: "Wearable thermoelectrics for personalized thermoregulation" Science Advances (2019). DOI: 10.1126/sciadv.aaw0536 , https://advances.sciencemag.org/content/5/5/eaaw0536
Journal information: Science Advances

Citation: Wearable cooling and heating patch could serve as personal thermostat and save energy (2019, May 17) retrieved 18 August 2019 from https://techxplore.com/news/2019-05-wearable-cooling-patch-personal-thermostat.html
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User comments

May 17, 2019
Someone at MIT already did this EXACT thing probably 2-3 years ago. I remember reading about it and discussing it with people here.

May 17, 2019
"The work is a collaboration between several research groups at the UC San Diego Jacobs School of Engineering. Chen's lab, which specializes in heat transfer technology, led the study."


@Benni
Heat transfer. This may be in your field of endeavour? (Thermodynamics/Entropy)

"It is powered by a flexible, stretchable battery pack and can be embedded in clothing. Researchers say wearing it could help save energy on air conditioning and heating."


Is this battery pack rechargeable? Could it be recharged from solar power/radiation? Does each pack have to be recharged separately or will they all be connected to be recharged as a single unit?
Will the battery packs one day be rechargeable from the human body's own electrical system/current?

May 17, 2019
There are several sites that expound on the human body's electrical system. Here is one:

https://health.ho...city.htm

It would be a good thing if the Researchers who are involved in that invention could find a way to somehow connect the battery pack(s) to use either solar power or the human body's own electrical generator. Or both to stay off the grid.

May 17, 2019
SEU, your future is this BORG; your every thought is this collective

Everyone is going to be like I-ROBOT, with an exoskeleton skin
Cooling, heating repelling mortars and shells
Those seem to abound these American streets now a days
Once these Americans complete this transition, each I-ROBOT is connected to this collective
Just as these BORG with their exoskeleton are connected to this collective

Welcome to your future SEU, you are one with this collective, you are BORG

p.s. SEU, when you are hot your body sweats to cool and shivers to warm when cold
our bodies have no energy to spare to supply power hungry electronics to warm or cool specific body parts
SEU, we convert energy at 25% which means for every 1lb we convert into energy we require another 3lbs which most evaporates as heat in sweat which defeats using our bodies for cooling
As you can see SEU we have no energy to spare

May 17, 2019
SEU, your future is this BORG; your every thought is this collective

Everyone is going to be like I-ROBOT, with an exoskeleton skin
Cooling, heating repelling mortars and shells
Those seem to abound these American streets now a days
Once these Americans complete this transition, each I-ROBOT is connected to this collective
Just as these BORG with their exoskeleton are connected to this collective

Welcome to your future SEU, you are one with this collective, you are BORG

p.s. SEU, when you are hot your body sweats to cool and shivers to warm when cold
our bodies have no energy to spare to supply power hungry electronics to warm or cool specific body parts
SEU, we convert energy at 25% which means for every 1lb we convert into energy we require another 3lbs which most evaporates as heat in sweat which defeats using our bodies for cooling
As you can see SEU we have no energy to spare
says gran

I am not in favour of the Collective which is Communism.
-contd-

May 17, 2019
-ontd-
But IF there is ever a chance that said battery packs will run on the smallest amount of continuous charging from the human nervous system that could be tapped into, with an additional few amps/volts, etc from sunshine, it would mean that this cooling/heating system would remain autonomous while it is being worn.
The article doesn't explain the source of energy for the batteries at present.

May 18, 2019
SEU be mindful what you wear it might be parasitic

Ignorance is bliss as you then do not miss - banned WhatsApping, banned Wikipedia on these mobiles
SEU> I am not in favour of the Collective which is Communism.

Creeping communalism abounds all around
as pointed out in these exoskeletons are a form of communism
mind controlling electronic devices
as SEU, their Ultimate aim is mind controlling parasitic devices
that send their tentacles into your nervous system
so beware as to what you wear SEU
It might be this latest fashion, but only because it parasitically is making you think it's fashionable

May 18, 2019
SEU be mindful what you wear it might be parasitic

Ignorance is bliss as you then do not miss - banned WhatsApping, banned Wikipedia on these mobiles
SEU> I am not in favour of the Collective which is Communism.

Creeping communalism abounds all around
as pointed out in these exoskeletons are a form of communism
mind controlling electronic devices
as SEU, their Ultimate aim is mind controlling parasitic devices
that send their tentacles into your nervous system
so beware as to what you wear SEU
It might be this latest fashion, but only because it parasitically is making you think it's fashionable
says granville

LOL I hadn't thought of that, granville. But you're right. Any invasion of the human nervous system could be a means of transmitting unwanted suggestions/thoughts into the human brain, possibly creating a "Resistance Is Futile" situation for the unfortunate person.
I guess we will choose to bypass this type of personal 'air-conditioning'.

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