Natural swing frequency of human hair - a novel method to quantify natural hair collective movements

The movement of a hair collective is a highly complex phenomenon with major contributions of hair-hair interactions, shape and alignment of the hair collective. All these influences are assessed and taken into account for further studies. The main objective is to investigate the relationship between the structural integrity of the inner hair fibers and the movement characteristics of hair strands for the driving factors, frequency and amplitude of movement. Furthermore, the influence of chemical treatments such as oxidative bleaching and hair relaxing on the movement characteristics have been quantified. In order to study the hair movement a novel method has been developed. By means of an automatic back-and-forth-hair-movement-device the swinging characteristics of standardized hair strands have been recorded by a high-speed camera (1000 frames/second) and analysed for different driving amplitudes and frequencies. Resulting maximal tip amplitudes and phase shifts were analyzed during the driven harmonic oscillation whereas natural frequency and the “damping factor”, respectively, have been determined for different hair qualities during the damping period after the driving force stopped.