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

Abstract

Our recent studies in the human skin signatures indicate a strong correlation between the human skin emissivity and factors such as the body mass index, the gender, the age, and the ethnicities of the participants. The key innovation in this is in recognising that signatures from the human body enable regions of the body to be identified as skin. This will enable increased the detection probabilities of anomalies, and reduced the false alarm rates in security screening portals. This is a capability that is being demanded internationally by governments and in the UK by the Home Office Future Aviation Security Solutions (FASS) programme and the Joint Security and Resilience Centre (JSaRC). In this paper, radiometric measurements conducted on human skin in the millimetre wave band region (80-100) GHz show variation in the human skin emissivity before and after conducting physical activity (jogging) subject to the same participant. The measurements were conducted on the palm of the hand and the back of the hand skin. The measurements reveal that the emissivity of the skin is significantly lower in the rest state of the body compared with the active state by mean values of 0.088 and 0.07 for the palm of the hand and the back of the hand skin respectively. The differences in the mean emissivity values were found to be linked to the length of time exercising and the hydration level of the skin i.e. (sweat). Radiometric measurements on palms of the hand and on the back of the hand skin before and after the application of an aqueous gel indicate a strong correlation between the human skin signature and the hydration level of the skin. The mean differences in emissivity values before and after the application of an aqueous gel indicate a scatter in the range of 0.02 to 0.26. These findings suggested trends in the human skin emissivity and indicate the potential of a new non-contact passive method for remote sensing of the physical state of human beings. Understanding these signatures and variations of the human skin emissivity are very important for both security screening (anomalies detection) and medical applications (non-invasive diagnosis of human body).

Synthetic Aperture Radar Imaging for Burn Wounds Diagnostics

“…Due to the grown interest of passive sensing technology, we have investigated the signature of the human skin over the millimeter wave band 80-100 GHz using non-contact sensor (radiometry) [22,23,[36][37][38]. Radiometric measurements performed on human skin [22,23,[36][37][38] indicate differences in the mean emissivity values of the skin between individuals, locations on the body, genders, and normal and wet skin.…”

“…Simulations results from the half space electromagnetic model in [22] show that the emissivity of the skin varies with the skin water content and this could be used as a metric to detect and monitor malignancy, eczema, psoriasis and burn wounds. In [23,[36][37][38] we have measured the emissivity of the human skin on different groups of healthy participants over the frequency band (80-100) GHz. Radiometric measurements in [36,37] indicate that there is a clear signature for the human skin over the millimetre-wave band and this signature can be detected using radiometry.…”

“…Radiometric measurements in [23] show a well define contrast in the emissivity of the human skin between thinner and thicker skin regions for both genders. Further, emissivity measurements in [38] indicate that radiometric sensitivity is sufficient to distinguish between normal skin and skin after the application of gel. These measurements [23,[36][37][38] reveal that variations in the human skin emissivity are related to the skin thickness and water content.…”

“…Further, emissivity measurements in [38] indicate that radiometric sensitivity is sufficient to distinguish between normal skin and skin after the application of gel. These measurements [23,[36][37][38] reveal that variations in the human skin emissivity are related to the skin thickness and water content. As burn wounds affect significantly the water content of the skin and the skin thickness; we have investigated the feasibility of using a single channel radiometry (passive sensing) to distinguish between unburned and burned skin in [2,27].…”

“…Experimental measurements in [21] indicate that the mono-static radar system is capable to provide precise information about the thickness of the dressing materials using the distance between two reflection peaks. In this paper an active microwave and millimetre-wave scanner (active imaging technology) combined with SAR image processing algorithm was used to scan images from porcine skin samples over the frequency band 15-40 GHz unlike other studies [2,[21][22][23]27,[36][37][38] that focus on measuring the mean emissivity values of the skin and the thickness of the dressing materials. The experimental images presented in this paper were extracted from the phase and the amplitude measurements of the input reflection coefficient.…”