A sweaty workout is a tough place to test a skin patch, and that is exactly where a new MIT hydrogel appears to hold up better than standard options.

In a study published in Nature, engineers led by a team at the Massachusetts Institute of Technology reported a hydrogel built with a stable, three-dimensional network of microscopic, air-filled channels. The material is designed for products that stay on the skin for hours or days, including wearable health sensors, medical patches and wound dressings.

Conventional hydrogels are water-rich, but they can trap heat and sweat, which may irritate skin and interfere with sensor readings. The new MIT material keeps a water content of 70 percent while creating internal air pathways that let oxygen and water vapour move through it.

The researchers said the design was inspired by the air-carrying architecture of human lungs. They added a small amount of silica aerogel particles, described as “solid-form” air bubbles, to a regular hydrogel recipe. Those water-repelling particles trapped air and stopped the tiny air spaces from collapsing or filling with water. During production, the particles joined inside the hydrogel to form a thin, interconnected network of air-filled channels.

In laboratory tests, the material reached an oxygen permeability of up to 185 barrer, about 10 times higher than a conventional hydrogel. It also transmitted water vapour at rates 10 to 100 times higher than silicone and polyurethane patches. The hydrogel stayed soft and durable, retaining about 95 percent of its air permeability after 10,000 stretching cycles.

To test wearability, researchers compared the new patch with a commercial silicone patch. Infrared images taken two minutes after removal showed skin temperature under the silicone patch rose by 6.5 degrees Celsius after a 20-minute workout. Under the new hydrogel, skin temperature fell by about 1 degree. The researchers also reported a substantial amount of sweat collected under the silicone patch, while skin covered by the breathable hydrogel remained similar to uncovered skin.

In another test, 10 volunteers wore the new patches on their chests during an hour of moderate exercise. None reported itching, irritation or other adverse skin reactions.

The team also adapted the hydrogel into an electrode that records the heart’s electrical activity. During cycling tests, conventional hydrogel electrodes produced less stable electrocardiogram, or ECG, signals as sweat built up. Electrodes made with the air-permeable hydrogel kept clearer readings during and after exercise.

In extended monitoring, the hydrogel electrodes were worn continuously for 10 days and kept recording usable ECG signals during sleeping, working, walking and exercising.

Xuanhe Zhao, the study’s senior author and a mechanical engineer at MIT, told ScienceAlert the most immediate uses could include wearable medical devices, wound dressings and skin-mounted health monitors.

“These technologies often require prolonged contact with the skin, but conventional hydrogels trap heat and moisture because they do not allow sufficient oxygen and water vapor to pass through,” Zhao said.

“Our material overcomes this limitation while maintaining the high water content and softness that make hydrogels comfortable and biocompatible.”

The material is not ready for clinical use. Zhao said further studies need to assess long-term biocompatibility, performance on large animals, sterilisation, manufacturing at scale, shelf life and regulatory safety.

The human testing in the study was small and focused mainly on showing feasibility. The exercise and comfort assessments involved up to 10 volunteers, the skin physiology measurements included two participants, and the exercise ECG comparison involved three. The material also is not inherently adhesive, so it still needs a separate backing or attachment mechanism to stay on the skin.

In the longer term, Zhao said the design could also be used in tissue engineering and implantable devices.

“Many engineered tissues and implants require efficient oxygen transport to maintain cell viability, and our material offers a way to improve gas exchange while preserving the hydrated environment that cells need,” Zhao said.

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