Assessment of Bandaged Burn Wounds Using Porcine Skin and Millimetric Radiometry.

This paper describes the experimental setup and measurements of the emissivity of porcine skin samples over the band of 80-100 GHz. Measurements were conducted on samples with and without dressing materials and before and after the application of localized heat treatments. Experimental measurements indicate that the differences in the mean emissivity values between unburned skin and burned damaged skin was up to ~0.28, with an experimental measurement uncertainty of ±0.005. Measured differences in the mean emissivity values between unburned and burn damaged skin increases with the depth of the burn, indicating a possible non-contact technique for assessing the degree of a burn. The mean emissivity of the dressed burned skin was found to be slightly higher than the undressed burned skin, typically ~0.01 to ~0.02 higher. This indicates that the signature of the burn caused by the application of localized heat treatments is observable through dressing materials. These findings reveal that radiometry, as a non-contact method, is capable of distinguishing between normal and burn-damaged skin under dressing materials without their often-painful removal. This indicates the potential of using millimeter wave (MMW) radiometry as a new type of medical diagnostic to monitor burn wounds.

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

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.

Local plasmon resonance at metal wedge.

A local plasmon resonance on a metal wedge is studied by using the Meixner approach [J. Meixner, IEEE Trans. Antennas Propag.AP-20, 442 (1972)]. It is found that the singular field behavior of a local plasmon resonance as a function of the distance from the edge of the wedge is sensitive to the wavelength and wedge angle, and ranges from a dramatic increase in amplitude close to its theoretical limit to pure oscillatory behavior with only minor amplitude variation. Field singularities for gold, silver, and aluminum wedges are calculated. It is shown that, unlike an ideal-conductor wedge, the real part of the power index of the electric field singularity does not decrease monotonically as a function of the wedge angle, but has a minimum for some angle depending on the wavelength and material parameters. If the dielectric surrounding the wedge has a positive permittivity equal to the absolute value of that of the metal, and hence satisfies the plasmon resonance condition, then the electric field has a peculiar behavior for a wedge whose shape is close to the flat surface.