Porcine skin as a surrogate for human skin in millimetre wave sensing research

Improving the security screening requires good knowledge and understanding of human skin signatures. Our previous publications indicate that the signature of the human skin varies from person to person under a dry and wet state. Human skin is a very sensitive organ and not all material can be applied or attached directly to the skin. Therefore, it is an essential requirement to find a close surrogate i.e. (animal tissue) and characterise similarities in signature between human and animal skin. The importance of this is that it will allow us to investigate more easily signatures of the human skin under different materials and conditions. This paper investigates signatures for the human skin and ex-vivo porcine skin samples using the 90 GHz calibrated radiometer. The paper aims to compare and show similarities and differences in the signature between human and ex-vivo porcine skin samples for the first time using millimetric wave radiometry. To this end, water and different types of cream were applied to the palm of the hand and porcine skin samples namely: skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream. The reflectance of the skin was measured before and after the application, with and without the presence of a clothing layer. Reflectance measurements on human skin were applied on six participants in the palm of the hand region for comparison with reflectance measurements of porcine skin from six samples taken from the back region of different animals. Reflectance measurements for the palm of the hand skin show that the mean reflectance values for all six participants are: 0.458, 0.618, 0.578, 0.548, and 0.488 for normal skin, skin with water, skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream respectively. For porcine skin samples, the mean reflectance values for all six samples are: 0.438, 0.608, 0.598, 0.558, and 0.508 for normal skin, skin with water, skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream respectively. These measurements indicate the similarities between the palm of the human hand and the back region of swine. The measurements also show that the difference in the mean reflectance values between the palm of the hand region and porcine skin for all cases is ~0.02. After adding a clothing layer made of textiles on the palm of the hand skin and porcine skin samples; the reflectance measurements for the palm of the hand skin become 0.408, 0.545, 0.498, 0.488, and 0.458 for normal skin, skin with water, skin with water jel, skin with silver sulfadiazine cream, and skin with betadine cream respectively. For porcine skin samples the mean reflectance values are: 0.388, 0.518, 0.488,0.488, and 0.478 respectively. These measurements indicate that textiles are relatively transparent over the frequency band (80-100) GHz and the signature of the skin can be observed through clothing. The increased understanding of these measurements brings means research into the medical applications of millimetre wave imaging to assess wounds under dressings. More specifically, subjects bearing bandaged wounds could be screened more reliably using imagers. In addition to the security screening applications and anomalies detection.