Stimulating the Comfort of Textile Electrodes in Wearable Neuromuscular Electrical Stimulation.

Hui Zhou,Ludovic Krundel,Wanzhen Chen,Haiqing Zou,Guanglin Li,Zhen Wu,Yi Lu

doi:10.3390/s150717241

Abstract

Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation. However, the stimulation comfort of textile electrodes and the mechanism behind stimulation discomfort is still unknown. In this study, a textile stimulation electrode was developed using conductive fabrics and then its impedance spectroscopy, stimulation thresholds, and stimulation comfort were quantitatively assessed and compared with those of a wet textile electrode and a hydrogel electrode on healthy subjects. The equivalent circuit models and the finite element models of different types of electrode were built based on the measured impedance data of the electrodes to reveal the possible mechanism of electrical stimulation pain. Our results showed that the wet textile electrode could achieve similar stimulation performance as the hydrogel electrode in motor threshold and stimulation comfort. However, the dry textile electrode was found to have very low pain threshold and induced obvious cutaneous painful sensations during stimulation, in comparison to the wet and hydrogel electrodes. Indeed, the finite element modeling results showed that the activation function along the z direction at the depth of dermis epidermis junction of the dry textile electrode was significantly larger than that of the wet and hydrogel electrodes, thus resulting in stronger activation of pain sensing fibers. Future work will be done to make textile electrodes have similar stimulation performance and comfort as hydrogel electrodes.

Highlights

Neuromuscular electrical stimulation (NMES) is a commonly used physical therapy method used in human subjects to re-educate motor function [1], increase peripheral blood circulation [2], improve muscle power, and help burning fat [3], etc. [4,5]
This study has investigated the electrical stimulation comfort of textile electrodes in comparison with traditional hydrogel electrodes
The electrical impedance spectral analysis showed a poor contact between the dry textile electrode and skin, while this contact was improved with a wet textile electrode

Summary

Introduction

Neuromuscular electrical stimulation (NMES) is a commonly used physical therapy method used in human subjects to re-educate motor function [1], increase peripheral blood circulation [2], improve muscle power , and help burning fat [3], etc. [4,5]. It would be desirable for users to make NMES therapy devices be convenient and wearable in everyday use for patients with various rehabilitation and healthcare needs. NMES devices mostly use self-adhesive hydrogel electrodes as stimulation electrodes. Hydrogel electrodes may cause skin irritation and allergic reactions in patients over time, their repeated use may be unhygienic, and they are not washable or properly sanitized after use. These limitations in use of conventional hydrogel electrodes in stimulation devices could make them uncomfortable and inconvenient for long time users. For more comfort and convenient stimulation, textile electrodes fabricated by the integration of conductive yarn into fabrics would be expected to be an alternative to hydrogel electrodes

Methods

Results

Discussion

Conclusion