Tactile sensation and attractiveness of hair bundles in the combing process

The tactile sensation of hair depends on its shape and mechanical properties. However, scientific analysis of hair bundles during the combing process is not a lot. This study explored hand movements and mechanical stimuli using an in-situ tactile sensing system to uncover the physical origin of tactile sensation and the attractiveness of three hair bundle types: straight, curly, and wavy. The straight hair type received the highest attractiveness score (6.9 ± 2.5), closely associated with the sensations of smoothness and slipperiness. While a higher smoothness score correlated with a smaller vertical force F_z, with a value exceeding eight at F_z < 1.2 N, a higher slippery sensation score correlated with a smaller moment M_x, with a value surpassing eight at M_x < 0.15 N m. Smooth and slippery sensations were implicated as the dominant factors of hair attractiveness. The smooth sensation arises when fingers glide through the hair during hand-combing without encountering resistance, while the slippery sensation is perceived as fingers pass through the ends of the hair with minimal force.