Enhancement of Plantar Tactile Sensitivity by Wearable Stabilization Device Based on Stochastic Resonance for Fall Prevention

Abstract

This article reports on the results of experiments that involved the use of a wearable sensorimotor enhancement device for preventing falls. The brief exposure of the tactile receptors to sub-sensory vibration is known to enhance tactile sensitivity, a phenomenon called “stochastic resonance” (SR) in the somatosensory system. Applying white-noise vibration to a tarsal tunnel is thus expected to improve plantar tactile sensitivity and improve the stability of the standing posture and gait. A prototype of a wearable device is proposed as part of this research. Eleven healthy young subjects (22.6±0.6 years old) were recruited for the plantar tactile enhanced test. Twenty-one healthy elderly subjects (73.3±4.6 years old) were recruited for the standing posture stabilization and gait tests. The elderly subjects were separated into two groups, one being a high-sensitivity group, and the other being a low-sensitivity group. The plantar tactile sensitivity of the healthy young subjects was found to be significantly increased in the plantar tactile enhanced test (p < 0.05). The total sway length (p < 0.05), lateral range (p < 0.05), velocity variability (p < 0.05), lateral velocity variability (p < 0.05), and lateral acceleration variability (p < 0.05) of COP in the standing posture stabilizing test were found to be significantly lower in the elderly subjects when using the prototype device. The step length in the gait test with the device was significantly increased in the high-sensitivity elderly group (p < 0.05). The results of the plantar tactile enhanced test showed that the mechanical vibration noise applied to the tarsal tunnel by the developed prototype device can enhance the plantar tactile sensitivity. The results of the standing posture stabilizing test and the gait test showed that the device can improve the static and dynamic balance control ability of the elderly subjects. These results suggest that the proposed device offers the potential of reducing the risk of fall accidents among the elderly.