Study on Photoacoustic Measurement Technique of Thermophysical Properties of Thick Solid Material and Human Skin

Abstract

The thermal effusivity and thermal diffusivity of thick solid materials were measured to validate a developed technique using a photoacoustic method. First, the thermal effusivity was determined by making close contact between an optically opaque sheet and the material. A titanium plate was used as the sheet with known thermophysical properties. Second, using the thermal effusivity as a known value, the thermal diffusivity was also determined by making close contact between an optically semitransparent sheet and the material. A rigid polyvinyl chloride plate was used as the thin sheet with known thermophysical and radiative properties, and a natural rubber block and an epoxy resin block were adopted as samples. The results indicated that the present technique was sufficiently accurate. The thermal effusivity and then the thermal diffusivity of human skin in vivo were measured noninvasively in the same way instead of the solid materials. The results also indicated that the present technique was sufficiently accurate for human skin.