Millimeter‐wave emissivity as a metric for the non‐contact diagnosis of human skin conditions

Abstract

A half‐space electromagnetic model of human skin over the band 30–300 GHz was constructed and used to model radiometric emissivity. The model showed that the radiometric emissivity rose from 0.4 to 0.8 over this band, with emission being localized to a layer approximately one millimeter deep in the skin. Simulations of skin with differing water contents associated with psoriasis, eczema, malignancy, and thermal burn wounds indicated radiometry could be used as a non‐contact technique to detect and monitor these conditions. The skin emissivity of a sample of 30 healthy volunteers, measured using a 95 GHz radiometer, was found to range from 0.2 to 0.7, and the experimental measurement uncertainty was ±0.002. Men on average were found to have an emissivity 0.046 higher than those of women, a measurement consistent with men having thicker skin than women. The regions of outer wrist and dorsal forearm, where skin is thicker, had emissivities 0.06–0.08 higher than the inner wrist and volar forearms where skin is generally thinner. Recommendations are made to develop a more sophisticated model of the skin and to collect larger data sets to obtain a deeper understanding of the signatures of human skin in the millimeter wave band. Bioelectromagnetics. 38:559–569, 2017. © 2017 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

Variation in the electromagnetic signatures of the human skin with physical activity and hydration level of the skin

“…The measurements in Figure 3 show the mean emissivity values of the skin before and after the application of an aqueous gel. Adding gel to the human skin increases the hydration level of the stratum corneum (SC) layer of the skin and reduces the inhomogeneity of the skin [10]. The gel that consists mainly of water can be used in the measurements of the dielectric properties of the skin in a wet state as it can stay adhered to the skin surface longer than the water.…”

“…Human skin emissivity and reflectance provide important diagnostic information and they have served as useful diagnostic tools in modern clinical medicine such as monitoring the wound healing under dressing materials [8,9], early detection of skin diseases [10,11], and identifying the mental state of the human [12]. In this paper, the signature of the human skin was measured before and after jogging on a treadmill and under normal and moistened skin conditions i.e.…”

Extended sources near-field processing of experimental aperture synthesis data and application of the Gerchberg method for enhancing radiometric three-dimensional millimetre-wave images in security screening portals

“…It is also known from the physics of millimetre wave interaction with the atmosphere that no radiation is generated from the empty air space surrounding an object, in a prospective security screening portal. It is therefore a reasonable assumption that millimetre wave radiation measured from within a portal only originates from a thin shell in 3D space comprising: the clothing of a person, any possible threat items and a fraction of a millimetre depth into the human skin [10]. This is valuable information when creating a 3D millimetre wave image of a person in a security screening portal.…”

“…Accurate data about how the signature of human skin looks is only just emerging. The levels of emission (and reflectance) are shown to be varying consistently over the different regions of the body, with age, gender and ethnicity [9], [10]. Exploiting this kind of machine based analysis will make for a screening system which is impossible to deceive.…”

Synthetic Aperture Radar Imaging for Burn Wounds Diagnostics

“…The relative demerits for this practice are being uncomfortable and painful to the patient (especially for children) [2]. As an alternative to the current medical practice, technologies are emerging to enhance the medical assessment of burn wounds such as terahertz imaging [4][5][6][7], optical coherence tomography [8][9][10][11][12], ultrasound imaging [13][14][15][16], infrared imaging [17][18][19][20], and microwave and millimetre wave (MMW) sensing [2,[21][22][23][24][25][26][27]. The latter is the subject of the research in this paper.…”