Development of an Electrotactile Haptic Device with Application to Balance Rehabilitation

Abstract

Balance impairments affect many individuals especially those in the older age bracket, and can lead to severe complications from falls. Research has shown that the cause of these impairments can be attributed to degraded sensory inputs. With ample sensory supplementation (or sensory augmentation), these deficiencies may be overcome. The purpose of this research is to verify a design of a low-cost custom electrotactile stimulation device that can aid in balance rehabilitation purposes. To this end, a major focus will be on wearability. Presently, there is a large research gap in the field of electrotactile stimulation for achieving wearable designs. Additionally, few devices incorporate a sensing mechanism for detecting balance impairment such as with an inertial measurement unit. Many researchers still rely on expensive commercial devices that are very large and bulky. Additionally, the design and implementation of electrotactile stimulation devices require working knowledge of circuits, thus there is mainly a general lack of instructions for the design of such devices. The thesis hopes to address these gaps by studying a design that may be simple to replicate from scratch. The design includes the use of several half H-bridge circuits to produce localized dipole stimulation through a 4 by 4 electrode array. Feasibility of the design will be verified via oscilloscope measurements and a small pilot study that is aimed at obtaining user feedback. The wearable components of the device include a custom-fabricated electrode array to be worn on the wrist or arm, and also an IMU (inertial measurement unit) belt along the waist to measure the user’s sway angle along the sagittal plane. Preliminary results show that a user can detect sensations from dry-skin stimulation while wearing the electrode array. The detected sensations also include directional information. Additionally, verification with the subject showed that the device is able to provide biofeedback through an electrode array as a result of the IMU orientation information. Further design refinements such as better point discrimination, pattern generation, and consistent pulsing are required before proceeding to the human testing and validation stage.