Experimentally derived viscoelastic properties of human skin and muscle in vitro

Measurement of the mechanical properties of human skin in vivo is challenging. Moreover, those with regard to excitation frequency have been rarely reported thus far. In this study, a vibration-based experimental method was employed to measure the viscoelastic properties with regard to the excitation frequency. Pieces of human skin and skeletal muscle excised from cadavers immediately post mortem were stored in a sealed container. As the experiment began, they were removed from the container and used to measure the viscoelastic properties as time elapsed. Young's moduli of the samples of human skin tissue that were immediately removed from the container were found to be similar to those obtained with in-vivo indentation methods. They were also found to be approximately one-third of those of human skeletal muscles. The viscoelastic properties of human skin were found to remain almost constant within the frequency range up to 120 Hz and are similar to those of porcine tissue. Young's moduli of the human skin and skeletal muscle were also found to reach the maximum values approximately five days post mortem. However, the loss factor of the human skin did not vary significantly as time elapses.