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Weir Weiss, Mary-Johanna

University of British Columbia

Below its outermost layer, skin tissue is permeable to fluid flow. Further understanding of skin tissue’s permeability could help with innovations related to intradermal vaccine and drug delivery, the development of artificial skin grafts, and other biomedical technologies concerning skin tissue and its pathologies. This work investigates porcine skin tissue as a poroelastic medium, where pressure driving fluid flow induces tissue deformation, affecting its permeability. A custom-made experimental setup applied a pressure driven fluid flow across skin tissue’s epidermal and dermal layers, which were supported by a porous, rigid base. Simultaneously, an Optical Coherence Tomography (OCT) system captured images of a cross section of skin tissue as it experienced deformation caused by pressure induced flow. Digital Image Correlation (DIC) was used to analyze the OCT images, thus providing the deformation field of the skin tissue. The image analysis corrected for the change in the tissue’s refractive index, which occurred due to fluid flow-induced deformation and thus change in the tissue’s water content. Skin tissue was found to exhibit a non-linear relation between pressure driving and the resulting fluid flow rate, where further increased pressure led to increased flow rate by lesser extents. The skin tissue was observed to experience compressive strain closest to the supported base, with magnitudes increasing with increasing driving pressure, and the free surface experienced relatively little deformation. A 1D depth-wise assumption was made concerning the skin tissue’s response to the pressure driven flow, then Darcy’s law and a permeability-strain relation were used to validate the results with good similarity between observed and calculated flowrates. The permeability-strain relation was found to have material constants: k₀ (initial uniform permeability) of 9.6 ×10ˉ¹⁵ m² with a standard deviation of 0.7 ×10ˉ¹⁵ m² and m (extent of nonlinearity for the material’s permeability-volumetric strain relation) of 2.94 with a standard deviation of 0.09. Overall, this work provides a fundamental understanding to skin behaviour under pressurized driving fluid, which can be generalized to study or model other geometries of induced flow through skin tissue.

Text

2023-04-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/84428

Mechanical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/