Dynamic understanding of human-skin movement and strain-field analysis.

Understanding the skin's material properties and natural motion is critical to a myriad of applications from tissue engineering to spacesuits. While there is an extensive understanding of human skin properties based on active tensile testing, both in vitro and in vivo, there is a little current knowledge of the strains experienced by skin during natural movements. Using a motion capture system, we have developed a new technique to measure skin movement and strain around the knee during a squatting motion. With these new data, we are also able to calculate the local direction of lines of nonextension, or contours of the skin that remain a constant length during motion, lines of minimum extension, and lines of minimum compression.