They develop smart “electronic skin” to monitor people’s health

MIT engineers working in South Korea have developed a sweat-resistant “electronic skin”. a breakthrough in more comfortable smart devices for everyday life and sports. This is a Adaptive adhesive patch integrated with a sensor that monitors a person’s health no misreading and no loss, even when the user is sweating.

The patch is modeled with artificial sweat ducts, similar to pores on human skin, that the researchers etched through the ultra-thin layers of the material. The pores pierce the patch in a kirigami-like pattern, similar to the Japanese art of paper cutting. The design ensures that sweat can escape through the patch, preventing skin irritation and damage to the built-in sensors.

The kirigami design also helps the patch to adapt to human skin when stretched and folded. This flexibility, along with the material’s ability to resist sweat, allows you to monitor a person’s health for long periods of time., which was not possible with previous smart skin designs. The results, published in Scientists progress, are a step towards long-lasting smart skin that can track daily vital signs or the progression of skin cancer and other conditions. “With this breathable and adaptable skin patch, there will be no sweat build-up, misinformation or skin loss,” he said in a statement. Release Jeehwan Kim, associate professor of mechanical engineering at MIT. “We can provide portable sensors that can continuously monitor long-term. “

Kim’s co-authors include Hanwool Yeon, senior and postdoctoral author at MIT, and researchers from the departments of Mechanical Engineering and Materials Science and Engineering at MIT, and the Electronics Research Laboratory, as well as collaborators from the cosmetics conglomerate. Amorepacific and other institutions in South Korea.

A sweaty obstacle

Kim’s group specializes in manufacturing flexible semiconductor films. Researchers have developed a technique called remote epitaxy, which involves the growth of high-quality, ultra-thin semiconductor films on high temperature wafers and the selective peeling of the films, which can then be combined and stacked to form much thinner and more flexible sensors than conventional designs platelet-based. Recently, her work caught the attention of cosmetics company Amorepacific, which wanted to develop a thin, wearable tape to constantly monitor skin changes. The company entered into a collaboration with Kim to turn the group’s flexible semiconductor films into something that could be used for long periods of time.

But the team was quickly faced with a hurdle that other electronic skin models have yet to overcome: sweat. Most experimental designs incorporate sensors into adhesive polymer materials that are not very breathable.. Other models, made from woven nanofibers, can pass air, but not sweat. If electronic skin worked long term, Kim realized that it should be permeable not only to vapor but also to perspiration.

“ESweat can accumulate between the electronic skin and the skin, which could cause skin damage and sensor malfunction“Kim says.” So we tried to solve these two problems at the same time, by allowing the sweat to penetrate through the electronic skin. “

Make the cut

In search of design inspiration, the researchers looked at human sweat pores. They found that the average pore diameter is around 100 microns and the pores are distributed randomly throughout the skin. They did some initial simulations to see how they could overlap and arrange the artificial pores, in a way that didn’t block the actual pores on human skin.

“Our simple idea is that if we provide artificial sweat ducts in the electronic skin and create highly permeable sweat paths, we can achieve long-term monitoring,” says Yeon. They started with a periodic pattern of holes, each the size of a real sweat pore. They found that if the pores were close together, at a distance less than the average diameter of a pore, the pattern as a whole would effectively permeate the sweat. But they also found that if this simple pattern of holes was etched through a thin film, the film was not very elastic and easily broke when applied to the skin.

The researchers found that they could increase the strength and flexibility of the hole pattern by cutting thin channels between each hole, creating a repeating dumbbell pattern, rather than single holes, which relax the tension, rather than the focus in one place. This pattern, when etched into a material, creates a stretchy effect similar to that of a kirigami. “If you wrap a piece of paper on a ball, it won’t fitKim said. “But if you cut out a kirigami pattern on the paper, it might be fine. So we thought, why not connect the holes with a cutout, to have kirigami-like conformability on the skin? , we can soak in sweat.

Following this reasoning, The team made an electronic skin from multiple functional layers, each of which is pore-etched with designs of weight. The layers of the skin include an array of sensors with ultra-fine semiconductor patterns to monitor temperature, hydration, UV exposure, and mechanical stress. This array of sensors is sandwiched between two thin protective films, all covered with a tacky polymer adhesive.

“Electronic skin is like human skin: very elastic and smooth, and sweat can pass through itYeon said. The researchers tested the electronic skin by sticking it to the wrist and forehead of a volunteer. The volunteer used the tape continuously for a week. Throughout this time, the new electronic skin reliably measured your temperature, hydration level, UV exposure, and pulse, even during sweat-inducing activities such as running on a treadmill for 30 minutes. minutes and consume a spicy meal.

El diseño del equipo también adapts itself to the piel, se pegaba a la frente del volunariens cuando se le pedía que frunciera el ceño repetidamente mientras sudaba profusamente, in comparison with otros diseños de pielónica que carecían de permeabilmente al sudaban y se despábilidad the skin. Kim plans to improve the strength and durability of the design. Although the tape is breathable and very adaptable, thanks to its kirigami pattern, it is this same pattern, along with the ultra-thin shape of the tape, that makes it quite brittle when rubbed.. As a result, volunteers had to wear a blanket around the tape to protect it during activities such as showering.

“Because electronic skin is so soft, it can be physically damaged,” Yeon explains. “Our goal is to improve the resilience of electronic skin.”

With information from MIT

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