The human body can only handle a certain amount of heat – or cold. This can be a problem in extreme environments, from polar subzero temperatures to the relentless heat of the Sahara, and it doesn’t stop at Earth. Maintaining temperature is also a problem for astronauts. The vacuum of space is a giant freezer, and the direct sunlight can be just as brutal as the cold.
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Technical garments that regulate body temperature usually only have one function: heating or cooling. In addition, they are often bulky and use a lot of energy, so the batteries eventually run out. What if there was a system that both heated and cooled while running on a constant source of renewable energy?
A team of researchers led by Ziyuan Wang from Nankai University in Tianjin, China, has taken on this challenge. Their result is a flexible, solar-powered system that can be integrated into clothing. It can regulate body heat by actively warming and cooling the skin. Besides, it works continuously for 24 hours and only needs sunlight to charge.
“In order to achieve the required sustainability and flexibility as well as low weight, the heat management unit for the body must have high energy transfer efficiency and low energy consumption,” the team said in the study recently published in Science.
Batteries not included
Wang’s new system combines the power of a solar cell with that of an electrocaloric device. The researchers used a flexible polymer for the solar cells. The electrocaloric device ensures the change in temperature when exposed to an electric field. Applying the field heats the material while removing the field cools it.
The system developed by Wang and his colleagues is made of a type of polyvinyl. This flexible material acts as an insulator, integrating a solar cell outside the polyvinyl with an electrocaloric device underneath. When exposed to sunlight, the solar cell does exactly what is expected of it by converting sunlight into electrical energy. This electricity is then transferred to the electrocaloric unit, where (assuming the system is in cooling mode) the appearance of an electric field heats the system. The energy generated by the solar cell is enough to keep the entire system running. The excess energy is stored in a separate energy storage unit.
Turn it up or turn it down
The energy stored during the day is especially useful after the sun has set. When it gets dark, the system automatically taps energy from the storage attachment to get you through the night. When it gets warmer or colder, the heating and cooling modes can be easily switched. And if the system runs out of power, it doesn’t need to be plugged in, but can be recharged using direct sunlight for 12 hours.
“With these two working modes, bidirectionally controllable thermoregulation for cooling and warming as needed can be realized,” said the researchers in the same.
So how can a researcher, astronaut, or anyone in an extreme environment wear this device? Wang suggests a suit with heating and cooling panels placed on the front and back of the chest, arms and legs. Because the panels are so flexible and light, such a garment would not weigh down a person exposed to blistering heat.
Although these thermoregulation techniques are not yet available, Wang hopes they will be a breakthrough for those who have to work in extreme environments – even for astronauts who have to brave the freezing darkness during a spacewalk.
The article originally appeared on Ars Technica.
(jl)
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