The skin stratum corneum (SC) is an intelligent interface with a thickness of only ~10 μm, preventing microbes and foreign substances from invading into our body as well as regulating the wa ter loss. Although the mechanism of the substance permeation through the SC has been intensively studied, it is still not conclusive. Here, we introduce some methods developed in our laboratory to clarify the relationship between the substance permeation and the SC structure. In order to analyze the minute structures of the SC collected non-invasively from the human skin, we developed a simple method for ultrathin cryo-section and a low-flux electron diffraction method for analysis of molecular packing in the intercellular lipid layer. In addition, we explain about the simultaneous measurement of the structure and the substance permeation by synchrotron X-ray diffraction and the experiment using artificial lipid membranes whose components can be easily controlled.

Scanning electron microscopy (SEM) has been widely used to examine various samples at visualizing of nanometer-scale resolution. Until now, the liquid samples have been examined by the various atmospheric holders using SEM. However, visualizing of unstained samples in water exhibits very poor contrast and heavy radiation damage. Recently, we developed new imaging technologies to the liquid specimens based on SEM. Our visualizing method produces high-contrast images of unstained and unfixed specimens in water. Moreover, the liquid specimens are not exposed directly to the electron beam; thus our method prevents electron radiation damage. Our method can be applied to diverse liquid specimens across a broad range of scientific fields, for example, biological samples, nanoparticles and organic materials.