Application of Raman and Near‐Infrared Spectroscopies to Skin Science

Abstract Spectroscopy is an indispensable analytical technique in many research fields, including basic and applied research. Spectroscopy‐based analytical techniques are applied in many industries, such as semiconductors, electronics, foods, pharmaceuticals, cosmetics, medical care, and energy and contribute to quality‐of‐life improvement. In skin science, aside from component analyses of medicines and cosmetic ingredients and quality guarantee analyses for inspecting foreign substances, the main measurement target is human skin itself. Spectroscopic techniques can be used to noninvasively obtain the molecular vibrational signatures of skin in and ex vivo, which is impossible to achieve using the invasive histological techniques widely used in skin research. In this article, I introduce the applications of spectroscopy in skin science, focusing on skin component evaluation. Specifically, I introduce our research using near‐infrared spectroscopy, spontaneous Raman spectroscopy, and coherent Raman imaging for evaluating the human skin's water and water‐binding components' contents and intracellular morphology, as inferred from the measured distributions of these components.