In this paper, we propose a soft vibrotactile actuator made by mixing silicon dioxide nanoparticles and plasticized PVC gel. The effect of the silicon dioxide nanoparticles in the plasticized PVC gel for the haptic performance is investigated in terms of electric, dielectric, and mechanical properties. Furthermore, eight soft vibrotactile actuators are prepared as a function of the content. Experiments are conducted to examine the haptic performance of the prepared eight soft vibrotactile actuators and to find the best weight ratio of the plasticized PVC gel to the nanoparticles. The experiments should show that the plasticized PVC gel with silicon dioxide nanoparticles improves the haptic performance of the plasticized PVC gel-based vibrotactile actuator, and the proposed vibrotactile actuator can create a variety of haptic sensations in a wide frequency range.

Vibrotactile technology has been gaining increasing interest for effective human-computer communication in various applications. In addition to psychophysical approaches commonly used to study tactile vibrations, neurocognitive responses to vibrotactile stimuli can provide new insights into mechanisms underlying human vibrotactile perception. In this study, we developed a magnetoencephalography (MEG)compatible vibrotactile stimulation device based on a polyvinyl chloride (PVC) gel actuator to study neuromagnetic somatosensory responses. A symmetric, double-layered PVC gel structure was applied to minimize the magnetic noise from the actuator. The device was used to generate sinusoidal stimuli at high frequencies to activate mechanoreceptors responsible for high-frequency vibrations greater than 50 Hz, and this device showed very little variability in stimulation onset time from the displacement measurements. We successfully observed vibrotactile-evoked magnetic fields by analyzing whole-head MEG data recorded during the high-frequency vibrotactile stimulation of the fingertips. Prominent peak responses were observed at approximately 56 ms (M50) in the contralateral hemisphere and at approximately 100 ms (M100) in both hemispheres. We identified the activation of contralateral primary somatosensory areas as a source of the vibrotactile M50 response. These results demonstrate the feasibility of using our new device to study vibrotactile perception with neuromagnetic imaging methods.