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

Zhou H, Lu Y, Chen W, Wu Z, Zou H, Krundel L, Li G - Sensors (Basel) (2015)

Bottom Line: Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation.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.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.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Human-Machine Intelligence-Synergy Systems of Chinese Academy of Sciences, Shenzhen 518055, China. hui.zhou@siat.ac.cn.

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.

No MeSH data available.


Related in: MedlinePlus

(a) Developed equivalent circuit model for the electrodes tested on leg muscle, with circuit elements including the electrode-skin impedance (Zelectrode-skin) and the body resistance (Rbody). The Zelectrode-skin is composed by electrode resistance (Relectode), and charge-transfer resistance (RT) and double-layer constant-phase element (ZCPE) at the electrode-skin interface; (b) A simplified equivalent circuit model for data fitting, with circuit elements including the total resistance (Rall) of body (Rbody) and electrode (Relectode), total charge-transfer resistance (RT-all) and total double-layer constant-phase element (ZCPE-all) at the electrode-skin interface.
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sensors-15-17241-f006: (a) Developed equivalent circuit model for the electrodes tested on leg muscle, with circuit elements including the electrode-skin impedance (Zelectrode-skin) and the body resistance (Rbody). The Zelectrode-skin is composed by electrode resistance (Relectode), and charge-transfer resistance (RT) and double-layer constant-phase element (ZCPE) at the electrode-skin interface; (b) A simplified equivalent circuit model for data fitting, with circuit elements including the total resistance (Rall) of body (Rbody) and electrode (Relectode), total charge-transfer resistance (RT-all) and total double-layer constant-phase element (ZCPE-all) at the electrode-skin interface.

Mentions: In order to facilitate data fitting, a simplified equivalent circuit model was proposed (shown in Figure 6), where Rall is the total resistance of the body (Rbody) and electrode (Relectrode), RT-all and ZCPE-all represent the total charge transfer resistance (RT) and double-layer constant-phase element (ZCPE) at the electrode-skin interface, respectively. The constant phase element (CPE) was introduced to represent the dissipative double-layer capacitance, which reflects the characteristics of a microscopic fractal at blocking electrode-electrolyte interfaces. The concept of CPE could be explained with the following equation: ZCPE = 1/[q(jω) n](1) where j = √-1, ω is the angular frequency (rad∙s−1) = 2πf, and f is frequency in Hz. The parameters of the CPE are defined by q and n. The parameter q indicates the value of the capacitance of the CPE as n approaches 1, and it has the numerical value of 1/ZCPE at ω = 1 rad/s. The parameter n reveals the micro fractal and distribution of the phase-phase interface. It correlates to energy dispersion on the electrode-electrolyte interface and can be affected by a series of factors, such as surface roughness, distribution of reaction rates, or a non-uniform current distribution. When n = 1, this CPE is identical to a capacitor.


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

Zhou H, Lu Y, Chen W, Wu Z, Zou H, Krundel L, Li G - Sensors (Basel) (2015)

(a) Developed equivalent circuit model for the electrodes tested on leg muscle, with circuit elements including the electrode-skin impedance (Zelectrode-skin) and the body resistance (Rbody). The Zelectrode-skin is composed by electrode resistance (Relectode), and charge-transfer resistance (RT) and double-layer constant-phase element (ZCPE) at the electrode-skin interface; (b) A simplified equivalent circuit model for data fitting, with circuit elements including the total resistance (Rall) of body (Rbody) and electrode (Relectode), total charge-transfer resistance (RT-all) and total double-layer constant-phase element (ZCPE-all) at the electrode-skin interface.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541932&req=5

sensors-15-17241-f006: (a) Developed equivalent circuit model for the electrodes tested on leg muscle, with circuit elements including the electrode-skin impedance (Zelectrode-skin) and the body resistance (Rbody). The Zelectrode-skin is composed by electrode resistance (Relectode), and charge-transfer resistance (RT) and double-layer constant-phase element (ZCPE) at the electrode-skin interface; (b) A simplified equivalent circuit model for data fitting, with circuit elements including the total resistance (Rall) of body (Rbody) and electrode (Relectode), total charge-transfer resistance (RT-all) and total double-layer constant-phase element (ZCPE-all) at the electrode-skin interface.
Mentions: In order to facilitate data fitting, a simplified equivalent circuit model was proposed (shown in Figure 6), where Rall is the total resistance of the body (Rbody) and electrode (Relectrode), RT-all and ZCPE-all represent the total charge transfer resistance (RT) and double-layer constant-phase element (ZCPE) at the electrode-skin interface, respectively. The constant phase element (CPE) was introduced to represent the dissipative double-layer capacitance, which reflects the characteristics of a microscopic fractal at blocking electrode-electrolyte interfaces. The concept of CPE could be explained with the following equation: ZCPE = 1/[q(jω) n](1) where j = √-1, ω is the angular frequency (rad∙s−1) = 2πf, and f is frequency in Hz. The parameters of the CPE are defined by q and n. The parameter q indicates the value of the capacitance of the CPE as n approaches 1, and it has the numerical value of 1/ZCPE at ω = 1 rad/s. The parameter n reveals the micro fractal and distribution of the phase-phase interface. It correlates to energy dispersion on the electrode-electrolyte interface and can be affected by a series of factors, such as surface roughness, distribution of reaction rates, or a non-uniform current distribution. When n = 1, this CPE is identical to a capacitor.

Bottom Line: Textile electrodes are becoming an attractive means in the facilitation of surface electrical stimulation.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.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.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Human-Machine Intelligence-Synergy Systems of Chinese Academy of Sciences, Shenzhen 518055, China. hui.zhou@siat.ac.cn.

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.

No MeSH data available.


Related in: MedlinePlus