Prof. Guy German developed a method to bond human skin to rubber-like polymeric materials without an adhesive. (Credit: Binghamton University)

A recent study explores how human skin can control the way cracks form. Researchers developed a method to bond human skin to rubber-like polymeric materials without an adhesive. They bonded skin samples to a piece of polydimethylsiloxane (PDMS), a rubber-like material commonly used in bioengineering and biomedical devices. The samples were then stretched. A modified traction force microscopy technique was then used to quantify changes in the mechanical loads imparted by the skin on the adherent substrate.

As the skin expanded, a little crack would grow, and they could measure how much energy it required to grow it by a certain length. The cracks propagate along the topographical microchannels. This elongates the overall path of the crack, increasing the energy it costs to break the tissue. The discovery can be extrapolated to explain the behaviors of other human tissues.

Because of the heterogeneous structure of skin, it also means that the crack path becomes a lot more random, causing variability in macroscale tensometer measurements. Even though you get the skin from the same source at the same age, the sample-to-sample variability is so high because the crack paths deviate.

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