Influence of silver/silver chloride electroless plating on the Shore hardness of polyurethane substrates for dry EEG electrodes

Abstract Dry electrodes enable a shorter preparation time for infant EEG. Since infant skin is more sensitive than adult skin, soft electrodes are required to reduce the mechanical stress for this sensitive skin. Thus, soft electrodes are crucial for eventual repetitive and long-term use like in neonatal intensive care units. A biocompatible polyurethane (PU) can be produced in low hardness resulting in a soft and flexible electrode substrate. Silver/silver chloride (Ag/AgCl) electroless plating provides a conductive, electrochemically stable coating but the process may alter the mechanical properties of the electrode substrate. In this study, we assess the hardness of PU material before and after Ag/AgCl plating. The test sample design for Shore hardness measurement is based on ISO 7619-1:2010. Sample production consists of a 3D print master model, silicone molding, PU casting, and finally electroless plating. UPX 8400-1 (Sika AG, Switzerland) is used for the sample substrates. Test samples are produced with 7 different Shore hardness (range A40-A95) and 14 samples (each hardness: 1 uncoated and 1 coated). The hardness measurements are carried out with a lever-operated test stand Shore hardness tester model with a digital hardness tester (TI-AC with HDA 100-1, KERN &SOHN GmbH, Germany).. It is shown that there is a hardness increase (Shore A) due to Ag/AgCl coating with a grand average of 1.1±0.7 (p<0.05). The largest increase of 2.1±0.2 is seen on the initial lowest Shore hardness sample (Shore hardness: 43.4±0.1). The absolute increase of hardness due to the Ag/AgCl coating decreases with increasing substrate hardness. It is concluded that there is no strong hardness increase of PU substrates due to Ag/AgCl plating. Therefore, the material is suitable as a soft electrode for repetitive and long-term use in infant applications.

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A Novel Highly Durable Carbon/Silver/Silver Chloride Composite Electrode for High-Definition Transcranial Direct Current Stimulation

Nanomaterials ◽

10.3390/nano11081962 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1962

Author(s):

Lingjun Li ◽

Guangli Li ◽

Yuliang Cao ◽

Yvonne Yanwen Duan

Keyword(s):

Service Life ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Silver Chloride ◽

Cycling Performance ◽

High Definition ◽

Silver Silver ◽

Sintered Ag ◽

Silver Silver Chloride

High-definition transcranial direct current stimulation (HD-tDCS) is a promising non-invasive neuromodulation technique, which has been widely used in the clinical intervention and treatment of neurological or psychiatric disorders. Sintered Ag/AgCl electrode has become a preferred candidate for HD-tDCS, but its service life is very short, especially for long-term anodal stimulation. To address this issue, a novel highly durable conductive carbon/silver/silver chloride composite (C/Ag/AgCl) electrode was fabricated by a facile cold rolling method. The important parameters were systematically optimized, including the conductive enhancer, the particle size of Ag powder, the C:Ag:PTFE ratio, the saline concentration, and the active substance loading. The CNT/Ag/AgCl-721 electrode demonstrated excellent specific capacity and cycling performance. Both constant current anodal polarization and simulated tDCS measurement demonstrated that the service life of the CNT/Ag/AgCl-721 electrodes was 15-16 times of that of sintered Ag/AgCl electrodes. The much longer service life can be attributed to the formation of the three-dimensional interpenetrating conductive network with CNT doping, which can maintain a good conductivity and cycling performance even if excessive non-conductive AgCl is accumulated on the surface during long-term anodal stimulation. Considering their low cost, long service life, and good skin tolerance, the proposed CNT/Ag/AgCl electrodes have shown promising application prospects in HD-tDCS, especially for daily life scenarios.

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Silver-silver chloride electrode as a nonpolarizable bioelectrode

Journal of Applied Physiology ◽

10.1152/jappl.1963.18.2.397 ◽

1963 ◽

Vol 18 (2) ◽

pp. 397-401 ◽

Cited By ~ 15

Author(s):

Walter Feder

Keyword(s):

Concentration Polarization ◽

Silver Chloride ◽

Stable State ◽

Routine Laboratory ◽

Silver Chloride Electrode ◽

Polarization Effects ◽

Laboratory Conditions ◽

Silver Silver ◽

Silver Silver Chloride

A thermal-electrolytic method for the preparation of Ag AgCl electrodes suitable for measurement of bioelectrical changes in the microvolt range is given in detail. A potential of 0.5 mv or less between electrode pairs is easily attained; and such electrodes will accurately measure emf generated by both steady and fluctuating phenomena down to ±5 μv under routine laboratory conditions. Studies in the variations in potential for pairs of electrodes from the time they are introduced into the circuit until they reach a stable state, as well as long-term drift are presented. These data are analyzed in terms of activation, ohmic, and concentration polarization effects. Submitted on July 19, 1962

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Development of Washable Silver Printed Textile Electrodes for Long-Term ECG Monitoring

Sensors ◽

10.3390/s20216233 ◽

2020 ◽

Vol 20 (21) ◽

pp. 6233

Author(s):

Abreha Bayrau Nigusse ◽

Benny Malengier ◽

Desalegn Alemu Mengistie ◽

Granch Berhe Tseghai ◽

Lieva Van Langenhove

Keyword(s):

Silver Chloride ◽

Signal To Noise Ratio ◽

Polyester Fabric ◽

Signal Quality ◽

Ecg Monitoring ◽

Textile Electrodes ◽

Elastic Strap ◽

Silver Silver ◽

Silver Silver Chloride

Long-term electrocardiography (ECG) monitoring is very essential for the early detection and treatment of cardiovascular disorders. However, commercially used silver/silver chloride (Ag/AgCl) electrodes have drawbacks, and these become more obvious during long-term signal monitoring, making them inconvenient for this use. In this study, we developed silver printed textile electrodes from knitted cotton and polyester fabric for ECG monitoring. The surface resistance of printed electrodes was 1.64 Ω/sq for cotton and 1.78 Ω/sq for polyester electrodes. The ECG detection performance of the electrodes was studied by placing three electrodes around the wrist where the electrodes were embedded on an elastic strap with Velcro. The ECG signals collected using textile electrodes had a comparable waveform to those acquired using standard Ag/AgCl electrodes with a signal to noise ratio (SNR) of 33.10, 30.17, and 33.52 dB for signals collected from cotton, polyester, and Ag/AgCl electrodes, respectively. The signal quality increased as the tightness of the elastic strap increased. Signals acquired at 15 mmHg pressure level with the textile electrodes provided a similar quality to those acquired using standard electrodes. Interestingly, the textile electrodes gave acceptable signal quality even after ten washing cycles.

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