Haptics: Neuroscience, Devices, Modeling, and Applications

Vibrotactile texture stimuli have commonly been used to produce sensations of roughness. The extension of such stimuli to other textural modalities enhances their applicability. We found that laterally asymmetric vibrotactile stimuli cause a sensation of friction rather than vibration. When a vibrotactile contactor moves in one direction, it sticks to the finger pad and induces lateral skin stretch. In contrast, when the contactor moves in the other direction, it slips because of its quick motion and induces little skin stretch. As a result, humans experience frictional sensations in scanning vibrating contactors with their fingertips. We examined participants’ subjective responses and measured interactive forces between the finger pad and the contactor. Both perceptual and physical experiments corroborated the hypothesis of the production of a sensation of friction. Laterally asymmetric vibrotactile stimuli increased stretching of the finger pad skin and increased the sensation of friction.