Effect of Ethnicity and Treatments on In Situ Tensile Response and Morphological Changes of Human Hair Characterized by Atomic Force Microscopy

In the 2008 study, researchers investigated the tensile response and morphological changes of human hair from different ethnicities and under various conditions using atomic force microscopy (AFM). They developed a technique to apply tension to hair fibers and to image the same area at different strains. The study compared virgin hair from Caucasian, Asian, and African ethnicities to understand ethnic differences. Additionally, it examined the effects of chemical damage and conditioner treatment on Caucasian hair when wet versus dry. The study also subjected virgin, damaged, and treated Caucasian hair to fatigue cycling to mimic combing and detangling. The results provided insights into the mechanical behavior of hair, which is relevant for the cosmetics industry, although the specific findings on the tensile response and morphological changes were not detailed in the summary.