Murine Skin Dosimetry Under Millimeter Wave Exposure

The upper part of the frequency spectrum (millimeter waves, MMW) applied by modern communications technologies (5G and beyond), makes skin the dominantly exposed tissue to electromagnetic fields. In this work, a methodology for murine skin dosimetry evaluation is presented, intended to contribute to animal studies with mice exposed to MMW radiation, in particular 27.5 GHz. A stratified skin model is proposed and the variations of the skin layers' thicknesses during a hair cycle are measured in mice. The variations of skin layers' dielectric properties due to age, based on the changes of total body water, are also evaluated. The impact of these variations in dosimetric metrics (i.e., mean absorbed power density, APD, and power loss) within each layer is assessed and found to be significant. Changes in the skin layers' thicknesses throughout a hair cycle considerably affect the APD, resulting in a two-fold increase, compared to changes in the dielectric properties due to aging or due to hair presence inside the skin.