Research on tactile perception by skin friction based on a multimodal method.

Background: Tactile perception is an essential function of skin. As this research involves many fields, such as skin friction, psychology, and neuroscience, the achievement tactile perception is scattered in various fields with different research methods. Therefore, it is necessary to study the whole tactile loop in a multimodal way, synchronizing all tactile information.

Materials And Methods: To measure information from touch to haptics, we developed a specially designed measuring platform connecting to an electroencephalogram (EEG) recording system. Sandpapers with different roughness were used as samples. First, the surface properties were measured in tribological experiments. Second, psychophysical experiments were conducted to assess the volunteers' cognition of samples' roughness. Third, the mechanical parameters and EEG were measured at the same time during fingertip sliding on samples. Then, the data of all four tactile elements were processed and analyzed separately. The characteristic features were extracted from those data in the time-frequency domain. Furthermore, the correlation coefficient was calculated in the pairwise comparison of each element to evaluate the feasibility of the multimodal method in the study of tactile perception.

Results: The 600-mesh sandpaper has the largest Ra, Rz, Rsm, and particle size. The normal load, friction force, spectral centroid, and α- and β-wave energy ratios of EEG at chosen electrodes have significant differences and correlations between 3000- and 600-mesh sandpaper in general.

Conclusion: This multimodal method could be used in the study of tactile perception, which is a comprehensive way to observe the whole tactile loop from multiple perspectives.