Assessment of Bandaged Burn Wounds Using Porcine Skin and Millimetric Radiometry

Abstract

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.

Keywords: burn wound; dressing materials; millimeter-wave; passive imaging; radiometry.

Figure 1

Illustration of different depth of invasion for burn injury [4,5].

Figure 2

Three-layer model for dressed burn wound comprising of: a semi-infinite layer of air, finite thickness layer of dressing materials, and a semi-infinite layer of burn-damaged skin.

Figure 3

Experimental setup for the emissivity measurements of the porcine skin samples. A digital voltmeter is used to measure the output voltage level of the samples and a thermocouple and an infrared thermometer are used to measure the thermodynamic temperature of the samples.

Figure 4

Radiometric emission centered at 90 GHz is collected by a moveable horn antenna at positions: A to measure a hot calibration source (1) (carbon loaded foam absorber; type: Eccosorb AN-73) stabilized at a temperature ~54 °C using a digital hotplate (3) placed in a polystyrene foam bucket (4), B to measure the cold calibration source (2) (carbon loaded foam absorber; type: Eccosorb AN-73) in thermodynamic equilibrium with air temperature ~20 °C.

Figure 5

A digital hotplate used for heating and stabilizing the surface temperature of the porcine skin samples (a) and a heat control device with (50 × 50 mm) metal plate used for performing burns on the porcine skin samples (b).

Figure 6

Mean emissivity values and standard deviation bars for porcine skin samples A, B, C, and D. The samples were taken from the back region of the same animal.

Figure 7

Mean emissivity values and standard deviation bars for porcine skin without and with dressing materials. The samples A, B, C, and D represent skin without dressing materials, A1, B1, C1, and D1 represent skin with six-layer gauze burn bandage, and A2, B2, C2, and D2 represent skin with a light support bandage.

Figure 8

Mean emissivity values and standard deviation bars for porcine skin samples (obtained from the same animal) before and after the application of localized heat treatment. Samples X, Y, Z, and W represent normal skin. X1 represents skin with burns after 10 s of heat treatment, Y1 represent skin with burns after 60 s of heat treatment. Z1 represents skin with burns after 120 s of heat treatment, and W1 represents skin with burns after 180 s of heat treatment. X2, Y2, Z2, and W2 represent skin with burns and dressing materials (six gauze burn bandage). X3, Y3, Z3, and W3 represent skin with burns and single-layer light support bandage.

Figure 9

Mean emissivity values and standard deviation bars for porcine skin samples (obtained from different animals) before and after different applications of localized heat treatments. Samples a, b, c, and d represent normal skin; a1, b1, c1, and d1 represent skin with burns after 10 s of heat treatment (first degree burn); a2, b2, c2, and d2 represent skin with burns after 60 s of extra heat treatment (second degree burn); a3, b3, c3, and d3 represent skin with burns after 120 s of extra heat treatment (third degree burn).

Figure 10

Mean emissivity values and standard deviation bars for porcine skin sample before and after different applications of localized heat treatments. L represents the normal skin; L1 represents skin with burns and exudates after 10 s of heat treatment, L2 represents skin with burns and without exudates after 60 s of extra heat treatment, L3 represents skin with burns and without exudates after 120 s of extra heat treatment.

Figure 11

Mean emissivity values and standard deviation bars for porcine skin samples (obtained from different animals) before and after different applications of localized heat treatments. Samples m and f represent normal skin; m1 and f1 represent skin with burns after 10 s of localized heat treatment, m2 and f2 represent skin with burns after 60 s of extra heat treatment, m3 and f3 represent skin with burns after 120 s of extra application of heat treatment, and m4 and f4 represent skin with burns after 180 s of extra application of heat treatment.