RVE based Finite Element Modelling of the Contact Mechanics Between Skin and Indenter

The nature of contact between human skin and external object (such as medical device, personal care device, fabric and so on) significantly influences the tactile perception and/or the functionality of the object. The contact mechanics depends strongly on the indenter properties and the mechanical properties of skin. Further, the topmost layer i.e., stratum corneum plays the most important role in tactile perception. In this study we use a representative volume element (RVE) based FEM model including the four layers of skin - stratum corneum, epidermis, dermis, and hypodermis - to simulate the contact mechanics between skin and a spherical indenter. The RVE model captures the mechanical properties of the microscopic constituents of the stratum corneum, which is the topmost layer of skin. We found that the RVE model can be used to simulate a variety of stratum corneum conditions (for example, dry and wet stratum corneum) and compositions. Using the RVE model in conjunction with an FEM model, we compute the frictional stress between skin and an indenter, as a function of stratum corneum microstructure, indentation depth, and local coefficient of friction. Both, the RVE model and the contact mechanics model predictions show good qualitative agreement with experimental findings in literature. Such studies will be very useful in in-silico design and optimization of devices that interact with skin. The current framework gives control over several parameters like skin microstructure, indenter or skin geometry and hence can be used to augment/substitute experimental testing.