Evaluation of Tactile Sensation and Friction Using Periodic Micro-structure of Etched Silicon Surface

Abstract

In this paper, we fabricated periodic micro-bump array structure on Si substrate to evaluate their tactile sensations. Fine-edged Si micro-bump array structures can be easily fabricated by photolithography and dry etching processes. Sensory evaluation of tactile feeling of roughness and frictional resistance with human finger was conducted with paired comparison method. In addition, friction coefficient between the micro-bump array and an artificial finger model that mimics our fingertip was evaluated. The result of sensory evaluation showed that rough feeling was affected by edges of the micro-bump structures even though the grooves between the micro-bumps were narrow as 20 µm. In contrast, frictional resistance feeling did not depend on the effect of the edges. It was strongly affected by a contact area between the micro-bump structure and finger skin. When the width of the grooves between the bump were 100 µm, finger skin entered and touch the bottom of the grooves, and then, the rough feeling and frictional resistance feeling were increased due to the contact area increment. The rough feeling and frictional resistance feeling have little correlation with the frictional coefficient measured with artificial finger model. It was more easy for human skin to enter the narrow grooves, in particular when the groove width was 100 µm.