Role of Fingertip Friction in the Tactile Perception of Surface Materials

Fingertip friction plays a key role in the stimulation of tactile perception upon sliding touch. We present psychophysical experiments with materials, whose tactile perception is dominated by their surface microstructure. Random roughness at the length scale of the finger ridge distance contributes more to the tactile perception of similarity than the resemblance of surface topography [1]. For micro-fibrillar surfaces, tactile perception follows the bending stiffness of fibrils rather than the elastic moduli or the length of fibrils [2]. The perception of frictional strength in sliding touch can be confused if the characteristic length scale of surface microstructure varies [3]. Finally, physiological characterization reveals the soft matter properties of fingertip skin and their influence on tactile perception of materials.<br/><br/>[1] R. Sahli, A. Prot, A. Wang, M.H. Müser, M. Piovarči, P. Didyk, R. Bennewitz, Tactile perception of randomly rough surfaces, Scientific Reports, 10 (2020) 15800.<br/>[2] A. Gedsun, R. Sahli, X. Meng, R. Hensel, R. Bennewitz, Bending as Key Mechanism in the Tactile Perception of Fibrillar Surfaces, Advanced Materials Interfaces, 9 (2022) 2101380.<br/>[3] M. Fehlberg, K.-S. Kim, K. Drewing, R. Hensel, R. Bennewitz, Perception of Friction in Tactile Exploration of Micro-structured Rubber Samples, in: H. Seifi, et al. (Eds.) Haptics: Science, Technology, Applications, Springer International Publishing, Cham, 2022, pp. 21-29.