Optoacoustics, laser-induced fluorescence (LIF), and photometry for investigation of different skin types in vitro and in vivo

Precise determination as well as comparison of optical properties of human skin in vivo and in vitro is of great importance to the understanding of effects of UV exposure. Because of that, the absorption properties of epidermal models without and with elanocytes of skin type IV and VI were examined using optical and optoacoustic spectroscopy. The effect of melanin as an important chromophor in human skin was investigated using a photometer, laser induced fluorescence (LIF) and optoacoustics. Moreover, an epidemal model irradiated several times with UVA showed similar absorption characteristics as human skin in vivo. Besides, optoacoustic signals are shown to deliver structural characteristics of different epidermal layers that are about 40 μm thick. Using laser optoacoustics and laser induced fluorescence, human skin in vivo can be investigated wavelength-resolved. Therefore, optoacoustics is a promising tool for in vivo determination of different skin types, optimization of phototherapy and testing of protective substances like sunscreens in the future.