A Wearable Transcutaneous Stimulator and Sensor System for Assessing the Effect of Stimulation On Postural Balance

Abstract

Sensory feedback is critical in the body’s effort to maintain balance while walking or standing. Deficits in balance due to age or medical conditions are common and may lead to falls and injury in those with reduced or weakened sensory feedback signals. Somatosensory feedback from the soles of the foot is one of the factors that is used by the central nervous system to regulate postural balance. The objective of this study is to create and use a wearable stimulation and sensor device to provide insight on whether stimulation-invoked somatosensory feedback at different regions of the soles of the foot has an impact on postural balance. Here, we present a wearable stimulation and sensor system designed to provide a configurable biphasic stimulus and collect measurements relevant to an individual’s balance. The device uses a 9-DoF inertial measurement unit, and transmits linear acceleration and Euler data wirelessly to a mobile device. Electrical stimulation applied based upon real-time data from an instrumented insole will evoke a sensory response at two different targeted regions of the foot: the sole of the heel and at the metatarsals and toes. Subjects were asked to perform multiple trials of five balance tests. Data collected was post-processed and analyzed to identify any noticeable trends inter-trial and intra-trial. Results suggest that this system has the potential for assessing sway parameters and other measures of an individual’s balance. However, it is unclear with the size of this subject group whether the stimulation intervention had an effect on improving balance.