Engineering news
Scientists at the Massachusetts Institute of Technology (MIT), Massachusetts General Hospital, Living Proof, and Olivo Labs have developed a wearable film that improves skin’s elasticity, reduces appearance of wrinkles and could be used to cover birthmarks or treat conditions such as eczema.
The material, a silicone-based polymer that could be applied on the skin as a thin, imperceptible coating, mimics the mechanical and elastic properties of healthy, youthful skin. In tests with human subjects, the researchers found that the material was able to reshape “eye bags” under the lower eyelids and also enhance skin hydration. This type of “second skin” could also be adapted to provide long-lasting ultraviolet protection, and with further development could be used to deliver drugs to help treat skin conditions such as eczema and other types of dermatitis.
Daniel Anderson, an associate professor in MIT’s Department of Chemical Engineering and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES), said: “It’s an invisible layer that can provide a barrier, provide cosmetic improvement, and potentially deliver a drug locally to the area that’s being treated. Those three things together could really make it ideal for use in humans.”
As skin ages, it becomes less firm and less elastic - problems that can be exacerbated by sun exposure. This impairs skin’s ability to protect against extreme temperatures, toxins, microorganisms, radiation, and injury. About 10 years ago, the research team set out to develop a protective coating that could restore the properties of healthy skin, for both medical and cosmetic applications.
“We started thinking about how we might be able to control the properties of skin by coating it with polymers that would impart beneficial effects,” said Amderson. “We also wanted it to be invisible and comfortable.”
The researchers created a library of more than 100 possible polymers, all of which contained a chemical structure known as siloxane - a chain of alternating atoms of silicon and oxygen. These polymers can be assembled into a network arrangement known as a cross-linked polymer layer (XPL). The researchers then tested the materials in search of one that would best mimic the appearance, strength, and elasticity of healthy skin.
The best-performing material has elastic properties very similar to those of skin. In laboratory tests, it easily returned to its original state after being stretched more than 250% (natural skin can be elongated about 18%). In laboratory tests, the novel XPL’s elasticity was much better than that of two other types of wound dressings now used on skin — silicone gel sheets and polyurethane films.
Barbara Gilchrest, a dermatologist at MGH and an author of the paper, said: “Creating a material that behaves like skin is very difficult. Many people have tried to do this, and the materials that have been available up until this have not had the properties of being flexible, comfortable, nonirritating, and able to conform to the movement of the skin and return to its original shape.”
The XPL is currently delivered in a two-step process. First, polysiloxane components are applied to the skin, followed by a platinum catalyst that induces the polymer to form a strong cross-linked film that remains on the skin for up to 24 hours. This catalyst has to be added after the polymer is applied because after this step the material becomes too stiff to spread. Both layers are applied as creams or ointments, and once spread onto the skin, XPL becomes essentially invisible.