Characterization of the biomechanical properties of human skin in vivo is studied both experimentally and by numerical modeling. These properties can be important in the evaluation of skin condition (e.g. aging) as well as skin disorders. In this study the authors focus on the static behavior of the dermis. Important features are stress-strain non-linearity and anisotropy; both are mainly determined by the collagen fiber network present in the dermis. A suitable constitutive model was developed by Lanir (1983). An experimental set-up was developed and used to stretch the skin in vivo. Two pads are attached to the skin which are driven apart during the experiment. The forces and displacements of the pads are measured. A field of markers (6*12) is applied to the skin's surface between the pads. The displacement history of the markers can be determined by image analysis. Both measured forces and displacement histories are input that is used to estimate the unknown material parameters in Lanir's skin model. A numerical simulation model of the experiment (finite element method) is combined with an estimation algorithm (constrained sequential maximum-likelihood approach) to determine estimates of the material parameters. Estimates of the skin parameters could be determined. However the procedure also shows that the skin model applied exhibits modelling errors.
|Title of host publication||Laser-tissue interaction XI : photochemical, photothermal, and photomechanical : 22-27 january 2000, San Jose|
|Place of Publication||Bellingham|
|Publication status||Published - 2000|
|Name||Proceedings of SPIE|