Viscoelastic properties of human skin and processed dermis

Background/aims: The purpose of this work is to attempt to determine the el astic spring constant for collagen and elastic fibers (elastin) in skin and to detemine if the values of these elastic constants are similar to those reported for other tissues. Methods: We studied the viscoelastic mechanical properties of human skin an d dermis by measuring the incremental stress-strain behavior. Elastic stres s-strain curves were used to obtain the elastic spring constant of elastin and collagen while the collagen fibril length was obtained from the slope o f viscous stress-strain curves. Results: Our results suggest that the elastic spring constant for elastin i s about 4.0 MPa while that for collagen is about 4.4 GPa. The former value is similar to that calculated for ligamentum nuchae while the latter value is about 70% of the value found for tendon and self-assembled type I collag en fibers. The differences between the elastic constants for collagen molec ules in tendon and skin is hypothesized to reflect the higher molecular til t angle and lower D period found in skin compared to tendon as well as a sh orter fibril length. Conclusion: The differences in the collagen types present in skin and tendo n may influence collagen self-assembly and the resulting viscoelastic prope rties.