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Updated: Jun 13, 2026
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Conformable Wearable Electrodes: From Fabrication to Electrophysiological Assessment
Published on: July 22, 2022
Biophysical and functional evaluation of concentric electrodes for localised non-invasive FES
Javier Saez1, Francisco Saavedra1, Rodrigo Osorio1
1Department of Electrical Engineering, Universidad de Concepción, Concepción, Chile.
Biomedical Physics & Engineering Express
|June 11, 2026
Summary
Concentric surface electrodes significantly improve spatial selectivity in functional electrical stimulation (FES) for upper limb applications. This innovation enhances neural targeting without increasing discomfort, offering a practical solution for neuroprosthetics.
Area of Science:
- Biomedical Engineering
- Neuroprosthetics
- Rehabilitation Technology
Background:
- Non-invasive functional electrical stimulation (FES) faces challenges with spatial selectivity, especially in complex upper limb anatomy.
- Conventional square surface electrodes exhibit limitations in precise neural targeting.
Purpose of the Study:
- To design, model, and validate concentric surface electrodes for enhanced spatial selectivity in FES.
- To compare the performance of concentric electrodes against conventional square electrodes.
Main Methods:
- A six-stage workflow involving electrode design, finite element method (FEM) modeling, axonal activation simulations (MRG model), additive manufacturing, impedance testing, and in-vivo human evaluation.
- FEM and MRG simulations were used to analyze electric field distribution and neural selectivity.
- Prototypes were fabricated and tested in 11 participants for motor response and comfort.
Main Results:
- FEM analysis showed concentric electrodes concentrate electric fields and reduce current spread compared to square electrodes.
- MRG simulations indicated improved neural selectivity with a wider high-selectivity range (Δ = 2.7 mA) for concentric designs.
- In-vivo tests demonstrated significantly higher selectivity indices for concentric electrodes (0.723 ± 0.175) versus square electrodes (0.546 ± 0.098) without increased discomfort.
Conclusions:
- Concentric surface electrodes offer a practical and scalable method to improve spatial selectivity in surface FES.
- The developed modeling-to-prototyping workflow facilitates rapid optimization of personalized neuroprosthetic interfaces.
