Design of a Wearable Vibrotactile Stimulation Device for Individuals With Upper-Limb Hemiparesis and Spasticity

Abstract

Vibratory stimulation may improve post-stroke symptoms such as spasticity; however, current studies are limited by the large, clinic-based apparatus used to apply this stimulation. A wearable device could provide vibratory stimulation in a mobile form, enabling further study of this technique. An initial device, the vibrotactile stimulation (VTS) Glove, was deployed in an eight-week clinical study in which sixteen individuals with stroke used the device for several hours daily. Participants reported wearing the glove during activities such as church, social events, and dining out. However, 69% of participants struggled to extend or insert their fingers to don the device. In a follow-up study, eight individuals with stroke evaluated new VTS device prototypes in a three-round iterative design study with the aims of creating the next generation of VTS devices and understanding features that influence interaction with a wearable device by individuals with impaired upper-limb function. Interviews and interaction tasks were used to define actionable design revisions between each round of evaluation. Our analysis identified six new themes from participants regarding device designs: hand supination is challenging, separate finger attachments inhibit fit and use, fingers may be flexed or open, fabric coverage impacts comfort, a reduced concern for social comfort, and the affected hand is infrequently used. Straps that wrap around the arm and fixtures on the anterior arm were other challenging features. We discuss potential accommodations for these challenges, as well as social comfort. New VTS device designs are presented and were donned in an average time of 48 seconds.

Fig. 1.

(a.) The VTS Glove, which provides wireless and wearable vibrotactile stimulation. (b.) Breakdown of activities performed while wearing the stimulation device, reported by sixteen persons with stroke in the clinical study.

Fig. 2.

(a.) Study structure. (b.) VTS Phalanx version V1. 1. A design resembling fingerless gloves with the palm exposed. 2. Rigid arches create a place for each finger without inserting each finger individually. 3. The two straps are capable of wrapping over flexed fingers without requiring finger extension. (c.) VTS Phalanx version V4. 1. The single strap over the fingers can be donned with the anterior arm facing away (no supination). 2. A T-strap design reduces fabric coverage while providing a path for wires to run between circuitry at the wrist and actuators at the fingers. 3. A buckle closure enables strap adjustment using one hand.

Fig. 3.

VTS Armband version V1 and version V4. (a.) 1. The rectangular armband wraps around the arm and attaches via Velcro. 2. The band has a width of 3 inches and circuitry can be mounted on or in the armband. (b.) 1. The rigid and tapered end of the armband is designed to slip through the 0.75 inch buckle frame. 2. The armband is 2 inches wide. 3. A cinch buckle enables users to secure the device using one hand.

Fig. 4.

VTS Palm version V1 and version V4. (a.) 1. The affected hand can be placed around the rod-shaped device. 2. An adjustable strap slips over the fingers. (b.) 1. The brace-like design contains foam which conforms to the palm when fingers are extended or flexed. 2. A single strap secures the fingers.

Fig. 5.

Quantitative data for each design and each round in the study. Participant numbers are listed by each data point. (a.) Time required to don the prototype for each participant. Each stack of markers represents one round in the study. (b.) Time to doff the prototype. (c.) Percent of participants who correctly donned the prototype for each round and each device.

Fig. 6.

Design features that participants struggled with in this study. (a.) Participants struggled to supinate their arm and expose the volar hand to stretch loops over each finger. (b.) Participants could not insert their fingers into finger sleeves. (c.) When magnets were placed between the fingers, participants struggled with fit and finger abduction.