Millimeter wave dosimetry of human skin

Abstract

To identify the mechanisms of biological effects of mm waves it is important to develop accurate methods for evaluating absorption and penetration depth of mm waves in the epidermis and dermis. The main characteristics of mm wave skin dosimetry were calculated using a homogeneous unilayer model and two multilayer models of skin. These characteristics included reflection, power density (PD), penetration depth (delta), and specific absorption rate (SAR). The parameters of the models were found from fitting the models to the experimental data obtained from measurements of mm wave reflection from human skin. The forearm and palm data were used to model the skin with thin and thick stratum corneum (SC), respectively. The thin SC produced little influence on the interaction of mm waves with skin. On the contrary, the thick SC in the palm played the role of a matching layer and significantly reduced reflection. In addition, the palmar skin manifested a broad peak in reflection within the 83-277 GHz range. The viable epidermis plus dermis, containing a large amount of free water, greatly attenuated mm wave energy. Therefore, the deeper fat layer had little effect on the PD and SAR profiles. We observed the appearance of a moderate SAR peak in the therapeutic frequency range (42-62 GHz) within the skin at a depth of 0.3-0.4 mm. Millimeter waves penetrate into the human skin deep enough (delta = 0.65 mm at 42 GHz) to affect most skin structures located in the epidermis and dermis.

Effects of 60-GHz millimeter waves on neurite outgrowth in PC12 cells using high-content screening

“…The finite-difference time domain method implemented in SEMCAD X was used here to perform a numerical dosimetry study. We calculated an equivalent incident power density using the following formula [13]:…”

“…As MMW penetration in the skin is very limited (i.e. between a few tenth to 1 mm in the therapeutic range (42 -62 GHz) [13,14]), the hypothesis of the activation of free nerve endings from the epidermis and upper dermis by MMW has been proposed [12]. The physiology of the nervous system involves a large panel of cellular processes such as proliferation, migration, differentiation, synaptogenesis and programmed cell death.…”

Reflection and penetration depth of millimeter waves in murine skin

“…This can be explained by the small difference in water content of different tissue layers except for the SC and fat layers. The thin SC and fat layers produced a small effect on the PD deposition [Alekseev et al, 2008].…”

“…Recently we have reported the results of a study of human skin permittivity using mm wave reflectometry [Alekseev and Ziskin, 2007] and human skin dosimetry [Alekseev et al, 2008]. Permittivity was determined for both homogeneous and multilayer skin models.…”

Investigations of Sar Distributions and Temperature Elevation on Human Body at 60 GHZ With Corrugated Antipodal Linear Tapered Slot Antenna

“…Hence, PD is not as useful as SAR or temperature for evaluating safety in mmW devices, especially in the near field. In several studies, SAR has been used as one of the dosimetric quantities at millimeter waves to study the exposure [9,19,31]. The spatial SAR distributions in homogeneous phantom models due to ALTSA are computed at 60 GHz using Ansys's HFSS.…”