Conference Contribution Details
P Xiao and RE Imhof
Poster Presentation, Stratum Corneum VI Conference, Boston 2009.
Diffusion through in-vivo human stratum corneum (SC) has always been an interesting research area, and the relative importance of intercellular routes (diffusion between corneocytes) and transcellular routes (diffusion through corneocytes) are often debated. In this paper, we describe a three dimensional finite element diffusion model to simulate water diffusion through the SC. It uses a brick-and-mortar structure to represent corneocytes and lipids of the SC respectively, and simulates the dynamic water diffusion processes through the SC from pre-defined initial and boundary conditions. Although the simulation is for water diffusion, the principles can also be applied to the diffusions of other topically applied substances.
The simulation results show that both intercellular routes and transcellular routes are important for water diffusion. Although intercellular routes have higher flux rates, most of the water still diffuses by the transcellular routes because of its higher cross-sectional area. The diffusion water flux, or trans-epidermal water loss (TEWL), is inversely proportional to corneocyte size, ie the larger the corneocyte, the lower TEWL and vice versa. There are also effects from SC thickness, external air conditions and diffusion coefficients for water within the corneocyte and lipid domains.
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