In vivo measurement of human dermis by 1064 nm-excited fiber Raman spectroscopy

Background/aims: Although chemical information on the dermis in vivo is highly important in skin research, an efficient method for gathering this information is yet to be developed. Here, we demonstrate that newly developed near-infrared (1064 nm) excited Raman spectroscopy is a powerful method for chemical analysis of human skin in vivo. Methods: We used a laboratory-constructed Raman spectrometer equipped with a highly sensitive near-infrared detector (Hamamatsu Photonics), an optical fiber probe and a 1064 nm Nd:YAG laser. Raman spectra of porcine skin (in vitro) and human skin (in vivo) were measured with this spectrometer. Results: The Raman spectrum of porcine skin measured from the outer side resembles that of the dermis more than that of the epidermis. The Raman spectra of human skin (cheek, forehead, inner forearm, outer forearm, palm) depend on the portion measured with the probe. The spectra of the forehead and inner forearm show larger lipid signals than that of the palm. Conclusions: The Raman spectrum of skin measured with the 1064 nm Raman system primarily reflects the chemical composition of the dermis. The 1064 nm excited Raman spectroscopy is useful for research of the dermis and skin appendages.