The Internal Structure of Hair Observed Using a Differential Phase Contrast Scanning X-Ray Microscope

Abstract

Although observations of the intact structure of human hair have been performed using various X-ray micro-tomography systems, it has been found difficult to obtain fine images due to the low sensitivity of those systems. In the present study, we utilized a differential phase contrast scanning X-ray microscope to observe the inner microstructure of hair in greater detail without prior sample processing. Permanent waving treatments induced micrometer-scale void structures within the cortex, while slender void structures were observed between the cuticle scales. Although such structural defects were not induced by bleach treatment, the structures of the overlapped laye (i.e., cuticle cellular boundary) become unclear. The present imaging technique clearly displayed different appearances of hair damage induced by permanent waving and bleach treatments.