Design and fast-fabrication of a system for functional electrical stimulation in upper limb of people with tetraplegia

Abstract

Study design: Proof of concept. Objectives: Standard Functional Electrical Stimulation (FES) systems can enhance motor learning in people with tetraplegia and are widely delivered by self-adhesive electrodes. Their limitations are dexterity, specific knowledge to place the electrodes on muscles, need to fix electrodes when they lose the gel layer, and time. We designed a new FES system, using an existing protocol of drinking-like movements, to the upper limb of a person with tetraplegia C5 that fits in any anthropometry and can be easily produced. Furthermore, we tested the system to assess its effectiveness and users’ perception during FES rehabilitation. Setting: São Carlos, SP, Brazil. Methods: A shell was designed with parametric design and fast-fabrication methods, and a stimulation unit and a smartphone application were developed. Questionnaires assessed the perceptions of a patient and a physiotherapist, about the usability of the new system in relation to standard FES. Kinematic data of drinking-like movements were collected from the patient wearing both systems and compared with data from an aged-matched control subject. Results: The results are a personalized shell and an intuitive FES system, overcoming the limitations of standard FES. The new system suggested better wrist-flexion control shown by the mean angles (−18.93°), then the other system (−59.35°), and compared with the control (−10.97°). Conclusions: Fast-fabrication with parametric design offers a promising alternative for personalizing FES systems, with potential for home use. Further studies are required including randomized clinical trials. [Figure not available: see fulltext.].