Viscoelastic response of human hair cortex

Area of Science:

• Biophysics
• Materials Science
• Dermatology

Background:

• Human hair's mechanical properties are crucial for understanding its structure and function.
• Current methods often analyze hair as a homogeneous material, potentially masking important regional differences.
• The distinct components of hair, such as the cortex, may possess unique viscoelastic characteristics.

Purpose of the Study:

• To develop and validate a novel methodological approach for the separate quantitative analysis of viscous and elastic components in human hair.
• To compare the viscoelastic properties of whole human hair with those of its cortex.
• To evaluate the potential of hair cortex viscoelasticity as a diagnostic marker for hair disorders.

Main Methods:

• Utilized a computerised experimental system for separate analysis of viscous and elastic hair components.
• Determined viscoelastic response (modulus of elasticity, limit of linearity, post-yield slope) of hair and its cortex.
• Conducted experiments on hair specimens from multiple subjects to assess variability.

Main Results:

• Statistically significant differences were observed between whole hair and hair cortex in viscoelastic parameters.
• The hair cortex exhibited significantly reduced dispersion in its viscoelastic parameters compared to whole hair.
• The microstructural features of the hair cortex strongly influence its viscoelastic pattern.

Conclusions:

• The hair cortex demonstrates more consistent and sensitive viscoelastic properties than whole hair.
• Hair cortex viscoelasticity serves as a potentially more reliable diagnostic marker for structural and functional hair disorders.
• The developed methodology enables precise characterization of hair biomechanics for diagnostic applications.