Touch-Sensitive Plastic Skin Heals Itself

Chemists and engineers at Stanford created the first synthetic material that is sensitive to touch and capable of healing itself quickly and repeatedly at room temperature.  This advance in technology can lead to smarter prosthetics.  Our skin sends brain precise information about pressure and temperature and can heal efficiently to preserve a protective barrier against the world.  Within the last year, there have been extraordinary advances in synthetic skin which have had success in self healing, but have come with some drawbacks.  Some drawbacks include that some had to be exposed to high temperatures (making them impractical for day-to-day use), some could heal at room temperature, but repairing a cut changed their mechanical or chemical structure, so they could heal themselves only once. Most important, no self-healing material was a good bulk conductor of electricity, which is a crucial property. 

Researchers at Stanford were able to get “the best of both worlds” by combining the self-healing ability of a plastic polymer and the conductivity of a metal. They began with a plastic consisting of long molecular chain joined by hydrogen bonds. These hydrogen bonds allow the material to self-heal. The molecules easily break apart, but then when they reconnect, the bonds reorganize themselves and restore the structure of the material.  The result of this reorganization is a bendable material. Researchers then added tiny particle of nickel to this resilient polymer. The added nickel increased its mechanical strength. The nanoscale surfaces of the nickel particles are rough, which proved important in making the material conductive. Then the researchers took a thin strip of the material and cut it in half with a scalpel to see how well the material could restore both its mechanical strength and its electrical conductivity after damage. After pressing the pieces together the material gained back 75 percent of its original strength and electrical conductivity. Another interesting result was that the same sample could be cut repeatedly in the same place. After 50 cuts and repairs, the sample withstood bending and stretching just like the original. Researchers found that even though nickel was key to making the material strong and conductive, it also got in the way of the healing process by preventing the hydrogen bonds from reconnecting as well as they should. Researchers suggested for future that they might adjust the size and shape of the nanoparticles, or even the chemical properties of the polymer. Researchers also tested the material as a sensor. Twisting or putting pressure on the synthetic skin changes the distance between the nickel particles which allow the electrons to move with ease. The material is sensitive enough to detect the pressure of a handshake. The material is sensitive not only to downward pressure but also to flexing, so a prosthetic limb might someday be able to register the degree of bend in a joint.

I found this article interesting because I hope to one day work with prosthetic engineering. I find the advances in research and technology that can impact prosthetic devices truly amazing and astounding. I feel that the possibilities for this type of research are endless. Unfortunately, there will always be a demand for prosthetics, so the possibility of giving a person an artificial limb that can’t replace what they lost, but help them lead a full life with no drawbacks.

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