Biomechanical properties of human hair with different parameters

Background/purpose: Investigations on the mechanical properties of human hair are inadequate. This research explores the break force of anagen hair by forming criteria according to the diameter of hair, gender, age, strain, use of drugs and hair dyes and how these criteria affect the mechanical resistance of hair.
Methods: The resistances of anagen hair of 120 volunteers were investigated in our biomechanics laboratory. The relationship between the value of break force of hair and hair diameter, gender, age, strain, use of drugs and hair dyes was examined. Tensile tests were applied to each hair with a 50 N load cell device.
Results: The statistical evaluation demonstrated a significant difference between the break forces of hairs with different hair diameters. The hairs with a diameter of 51 μm and above had a significantly higher break force than those of 50 μm and below ( P =0.000). An insignificant correlation was observed between break force and strain ( P =0.554, r =−0.055) whereas the correlation between diameter and strain was statistically significant ( P =0.000, r =0.361).
Conclusion: The break force of hairs did not show any significant dependency on age, presence of hair dyes, gender and usage of drugs. Yet, a statistically significant difference was observed between the break forces of hairs when compared according to their diameters and strain. More research on the mechanical properties of human hair consistent with biological properties like protein structure, α keratin fibers and microfibril–matrix composite behaviors would guide dermatologists for diagnostic symptoms.