A Raman Spectroscopy Investigation of the Resilience of Hair Cuticular Scales Under Uniaxial Stress

This study uses Raman spectroscopy to examine the resilience of human hair cuticular scales under uniaxial stress, focusing on their mechanical behavior. It finds that stretching hair increases the distance between cuticle scales and creates iridescent regions near scale edges, emphasizing the cuticle's role in hair's mechanical response. The research identifies three stress-strain behavior regions: elastic, plastic deformation, and failure. In the plastic region, scales follow macrostrain linearly, while in the failure region, keratinocyte coherence is lost. Disulfide bridges change geometrically, but keratin structure remains unchanged. The study underscores the cuticular cell membrane complex's importance in maintaining structural integrity through lipid layer thinning and scale gliding.