Figure 2
ETPS sensors of epidermal hydration and volumetric heat capacity. (a) Infrared (IR) image of epidermal 1 mm epidermal transient plane source (ETPS) element on hydrated pig skin (90% saline by weight) before heating, 1 and 2 s after heating starts, respectively. (b) IR images of same sensor, at same time points, on dehydrated pig skin (45% saline by weight). (c) Thermal conductivity (red) and maximum temperature attained at 2 s (blue) as measured by 1 mm ETPS sensor on pig skin at different hydration levels. (d) Thermal diffusivity measured by ETPS on pig skin sample at different hydration levels. (e) Volumetric heat capacity derived from ETPS sensor (blue) and specific heat capacity measured by differential scanning calorimetry (DSC, red), on pig skin samples at different hydration levels. (f) Volumetric heat capacity (blue) measured by ETPS sensor, plotted against specific heat capacity measured by DSC for a range of test materials with properties similar to those of skin. In c–f, error bars represent standard deviation across four elements, each measured three times.
