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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

Finite element model of dry textile electrode; three dimensional view of the model is shown in (a), side view is shown in (b), and the details of modeled dry textile electrode is shown in (c).
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sensors-15-17241-f004: Finite element model of dry textile electrode; three dimensional view of the model is shown in (a), side view is shown in (b), and the details of modeled dry textile electrode is shown in (c).

Mentions: In order to more deeply understand discomfort sensations during stimulation, three dimensional finite element models of different electrode types were developed with the aid of software (COMSOL Multiphysics 4.3a, COMSOL, Stockholm, Sweden). The skin model represented a 2 cm × 7 cm area of human skin, which consisted of five horizontal layers: stratum corneum, epidermis, dermis, fat, and muscle, as illustrated in Figure 4. The thickness and electrical parameters of each layer are listed in Table 1. For the dry textile electrode, since the conductive fabric touched with skin directly, only a layer of square shaped sheet with a thickness of 0.4 mm was modeled (see Figure 4). The conductivity value of dry textile electrode was estimated from the measured resistance of conductive fabric. The line width was set at 0.15 mm with a separation of 0.35 mm by approximate estimation from the microphotos of dry textile electrodes. Besides, the wet textile electrode could be treated as homogeneous conductive solution similar to 0.9% NaCl. Then the conductivity of wet textile electrode was set as 1.4 S/m in the model. The thickness of the wet textile electrode was set as 5.8 mm, which was estimated from two layers of conductive fabric (0.4 mm each) and a sandwiched absorbent sponge (5 mm). The hydrogel electrode was modeled as a foil and a layer of hydrogel [20]. All electrodes were modeled as 1 cm length × 1 cm width. A stationary electrical field of the skin area was developed in the model [21]. Both the anode (return) and cathode electrodes were placed on the surface of stratum corneum with a separation distance of 6 cm. The top surface of the anode electrode was set as the ground and the top surface of the cathode electrode was set as the stimulation current source (−2 mA).


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)

Finite element model of dry textile electrode; three dimensional view of the model is shown in (a), side view is shown in (b), and the details of modeled dry textile electrode is shown in (c).
© Copyright Policy
Related In: Results  -  Collection

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

sensors-15-17241-f004: Finite element model of dry textile electrode; three dimensional view of the model is shown in (a), side view is shown in (b), and the details of modeled dry textile electrode is shown in (c).
Mentions: In order to more deeply understand discomfort sensations during stimulation, three dimensional finite element models of different electrode types were developed with the aid of software (COMSOL Multiphysics 4.3a, COMSOL, Stockholm, Sweden). The skin model represented a 2 cm × 7 cm area of human skin, which consisted of five horizontal layers: stratum corneum, epidermis, dermis, fat, and muscle, as illustrated in Figure 4. The thickness and electrical parameters of each layer are listed in Table 1. For the dry textile electrode, since the conductive fabric touched with skin directly, only a layer of square shaped sheet with a thickness of 0.4 mm was modeled (see Figure 4). The conductivity value of dry textile electrode was estimated from the measured resistance of conductive fabric. The line width was set at 0.15 mm with a separation of 0.35 mm by approximate estimation from the microphotos of dry textile electrodes. Besides, the wet textile electrode could be treated as homogeneous conductive solution similar to 0.9% NaCl. Then the conductivity of wet textile electrode was set as 1.4 S/m in the model. The thickness of the wet textile electrode was set as 5.8 mm, which was estimated from two layers of conductive fabric (0.4 mm each) and a sandwiched absorbent sponge (5 mm). The hydrogel electrode was modeled as a foil and a layer of hydrogel [20]. All electrodes were modeled as 1 cm length × 1 cm width. A stationary electrical field of the skin area was developed in the model [21]. Both the anode (return) and cathode electrodes were placed on the surface of stratum corneum with a separation distance of 6 cm. The top surface of the anode electrode was set as the ground and the top surface of the cathode electrode was set as the stimulation current source (−2 mA).

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