Physics of Biology

The Stern Layer Contribution to Electromagnetic Absorption in Biological Skin

Authors: Luisiana X. Cundin, William P. Roach
Comments: 9 Pages.

Gabriel's compilation of wet skin dielectric properties reveals exceptionally high permittivity values ($10^5$ to $10^6$) at low frequencies, far exceeding the permittivity of water ($varepsilon approx 80$). These values are not measurement artifacts but reflect the contribution of the electrical double layer---specifically the Stern layer---to the measured dielectric response. The Stern layer confounds dielectric measurements by introducing a multiplicative capacitive contribution that masks the tissue's true dielectric properties. Using the Maxwell-Wagner transformation, $varepsilon_r'' = varepsilon_0 omega sigma_{text{exp}}'$, from the Cundin-Roach Kramers-Kronig analysis, we recover the intrinsic tissue absorption. The corrected absorption values are consistent with pure liquid water, confirming that biological tissue is fundamentally a water-based dielectric whose low-frequency response is dominated by the Stern layer capacitance. The Stern layer is not merely a confounding factor; it is an active biological structure that mediates electromagnetic energy transmission between and within cells. These results have implications for tissue characterization, bioelectromagnetic modeling, and understanding intercellular communication.
Category: Physics of Biology