scholarly journals Characterization of Ag/AgCl Dry Electrodes for Wearable Electrophysiological Sensing

2022 ◽  
Vol 2 ◽  
Author(s):  
Min Suk Lee ◽  
Akshay Paul ◽  
Yuchen Xu ◽  
W. David Hairston ◽  
Gert Cauwenberghs
Keyword(s):  
Electrochemical Impedance ◽  
Silver Chloride ◽  
Low Cost ◽  
The Body ◽  
Clinical Environment ◽  
Electrical Stability ◽  
Dry Electrodes ◽  
Auditory Steady State Response ◽  
Silver Silver ◽  
Silver Silver Chloride

With the rising need for on-body biometric sensing, the development of wearable electrophysiological sensors has been faster than ever. Surface electrodes placed on the skin need to be robust in order to measure biopotentials from the body reliably and comfortable for extended wearability. The electrical stability of nonpolarizable silver/silver chloride (Ag/AgCl) and its low-cost, commercial production have made these electrodes ubiquitous health sensors in the clinical environment, where wet gels and long wires are accommodated by patient immobility. However, smaller, dry electrodes with wireless acquisition are essential for truly wearable, continuous health sensing. Currently, techniques for the robust fabrication of custom Ag/AgCl electrodes are lacking. Here, we present three methods for the fabrication of Ag/AgCl electrodes: oxidizing Ag in a chlorine solution, electroplating Ag, and curing Ag/AgCl ink. Each of these methods is then used to create three different electrode shapes for wearable application. Bench-top and on-body evaluation of the electrode techniques was achieved by electrochemical impedance spectroscopy (EIS), calculation of variance in electrocardiogram (ECG) measurements, and analysis of auditory steady-state response (ASSR) measurement. Microstructures produced on the electrode by each fabrication technique were also investigated with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The custom Ag/AgCl electrodes were found to be efficient in comparison with standard, commercial Ag/AgCl wet electrodes across all three of our presented techniques, with Ag/AgCl ink shown to be the better out of the three in bench-top and biometric recordings.

scholarly journals Comparison of three types of dry electrodes for electroencephalography

ACTA IMEKO ◽  
2014 ◽  
Vol 3 (3) ◽  
pp. 33 ◽  
Author(s):  
Patrique Fiedler ◽  
Jens Haueisen ◽  
Dunja Jannek ◽  
Stefan Griebel ◽  
Lena Zentner ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Silver Chloride ◽  
Measurement Range ◽  
Open Circuit ◽  
Signal Acquisition ◽  
The Novel ◽  
Dry Electrodes ◽  
Dry Electrode ◽  
Silver Silver ◽  
Silver Silver Chloride

A potential new area of routine application for electroencephalography (EEG) is the brain-computer interface, which might enable disabled people to interact with their environment, based on measured brain signals. However, conventional electroencephalography is not suitable here due to limitations arising from complicated, time-consuming and error-prone preparation. Recently, several approaches for dry electrodes have been proposed. Our aim is the comparison and assessment of three types of dry electrodes and standard wet silver/silver-chloride electrodes for EEG signal acquisition. We developed novel EEG electrodes with titanium and polyurethane as base materials, which were coated with nanometer sized titanium-nitride films. Furthermore gold multi-pin electrodes were arranged on printed circuit boards. The results of the comparison of these electrodes with conventional wet silver/silver-chloride electrodes in terms of electrode impedances are presented, as well as open circuit potentials and biosignal measurements. Impedances were significantly higher for all dry electrode types compared to wet electrodes, but still within the measurement range of today’s standard biosignal amplifiers. It was found that the novel dry titanium and polyurethane based electrodes show biosignal quality equivalent to conventional electrodes. In conclusion, the novel dry electrodes seem to be suitable for application in brain-machine interfaces.

Roll-to-roll electrochemical fabrication of non-polarizable silver/silver chloride-coated nylon yarn for biological signal monitoring

2018 ◽  
Vol 89 (17) ◽  
pp. 3591-3600
Author(s):  
Peter A Haddad ◽  
Amir Servati ◽  
Saeid Soltanian ◽  
Peyman Servati ◽  
Frank Ko
Keyword(s):  
Silver Chloride ◽  
The Body ◽  
Fabrication Process ◽  
Electronic Textiles ◽  
Applied Current ◽  
Counter Electrodes ◽  
Roll To Roll ◽  
Voltage Limit ◽  
Silver Silver ◽  
Silver Silver Chloride

The main goal of this work is to develop a fabrication process and system for silver/silver chloride (Ag/AgCl)-coated yarn, as Ag/AgCl is the preferred non-polarizing material for interfacing with the body in a clinical setting when monitoring biological signals. A roll-to-roll electrochemical system was designed and built to deposit AgCl on Ag-coated nylon 6,6 yarn in a controllable process. In particular, the movement of the yarn, voltage limit and mixing of 0.9% sodium chloride solution were held constant while the applied current was varied. The Ag-coated nylon acted as the working electrode with two counter electrodes made of platinum. The optimal Ag/AgCl yarns were then further characterized. The roll-to-roll parameters identified include the applied current of approximately 1.82 mA/cm2 for the Ag-coated nylon yarn with a voltage limit of 2.00 V while in the electrochemical chamber. In addition, the yarn had a uniform movement of 0.08 cm/s, which meant that 7 cm of yarn was in the chamber for approximately 89.17 s. The fabrication process was relatively repeatable, yielding the average resistance of 11.0 ± 1.8 Ω/cm for the optimal Ag/AgCl-coated yarn with a low standard deviation between different fabrication processes. A proof-of-concept system was developed and parameters important for the fabrication of functional Ag/AgCl electronic textiles (e-textiles) were detailed. An effective roll-to-roll fabrication method for Ag/AgCl-coated yarns has the potential to significantly contribute to the design and development of wearable e-textile biological monitoring systems that require Ag/AgCl sensor materials.

Electrochemical Modification of Silver Coated Multifilament for Wearable ECG Monitoring Electrodes

2011 ◽  
Vol 332-334 ◽  
pp. 1019-1023 ◽  
Author(s):  
Peng Jun Xu ◽  
Hao Liu ◽  
Hui Zhang ◽  
Xiao Ming Tao ◽  
Shan Yuan Wang
Keyword(s):  
Processing Time ◽  
Electrochemical Impedance ◽  
Silver Chloride ◽  
Structure Design ◽  
Electrolytic Deposition ◽  
Material System ◽  
Electrode Structure ◽  
Silver Silver ◽  
Silver Silver Chloride ◽  
Design And Testing

This paper presents a method to fabricate textile structural electrodes from material preparation to electrode structure design and testing. Silver/Silver Chloride (Ag/AgCl) was assumed to be the best electrode material system for acquisition of biopotential signals. A AgCl coating has been grown on silver (Ag) coated multilament yarn to form Ag/AgCl combination using constant voltage electrolytic deposition in 0.9% wt sodium chloride bath. The AgCl thickness could be controlled by varying processing time (t) and voltage (V). Surface morphology of the treated fibres were studied by scanning electron microscopy (SEM) which revealed that AgCl grain size became bigger and denser as increased processing time and voltage. The impedance of the treated fibre was analyzed by electrochemical impedance spectroscopy (EIS) analysis from 0.1H z to 1000H z which shown that impedance also increased with processing time and voltage. The prepared Ag/AgCl multilament yarn was fabricated into wearable electrode using embroidery technique. ECG testing confirmed that the electrodes made from treated fibre can acquire high quality signal.

Electrophysiology and Stimulation

2011 ◽  
Author(s):  
Patrick Magee ◽  
Mark Tooley
Keyword(s):  
Silver Chloride ◽  
Cardiac Injury ◽  
The Body ◽  
P Wave ◽  
Anatomical Landmarks ◽  
Surface Reflection ◽  
Silver Silver ◽  
The Right ◽  
Silver Silver Chloride ◽  
Electrocardiogram Ecg

This chapter covers the processing and application of electrical signals from the body, in particularly the electroencephalogram (EEG), the electrocardiogram (ECG), and the electromyogram (EMG). The EEG and ECG will be considered in their monitoring capacity. The EMG will be discussed along with simulation and neuromuscular blockade and monitoring. The electrocardiogram (ECG) is a surface reflection of the propagation of electrical depolarisation and repolarisation over the various contractile chambers of the heart. Depolarisation is the trigger for releasing the stored contractile energy in the cardiac muscle. Each chamber also produces electrical action and polarising recovery potentials associated with the mechanical contribution of the recovery. The ECG can be divided into two major components: one associated with the propagation of excitation and recovery of the atria; the other with these events occurring in the ventricles. Excitation of the atria gives rise to the P wave, after which the atrial contractions propel blood into the ventricles. An atrial recovery wave exists, but it is rarely seen, as it is obscured by ventricular excitation, which is signalled by the QRS wave. During the later part of the QRS wave, ventricular contraction commences. Recovery of the ventricles is preceded by the T wave. The ECG labels, i.e. PQRST, are shown in Figure 18.1. To localise the direction of excitation and recovery of the heart chambers (and also to estimate the extent of cardiac injury), a variety of electrode arrangements can be used. The electrodes (which are normally disposable silver–silver chloride as described in Chapter 5) are positioned on easily located anatomical landmarks such as the right arm (RA), the left arm (LA), and the left leg (LL), with the right leg usually providing the reference or common. The standard (1, II, III), augmented (aVR, aVL, aVF) and precordial (V) leads are routinely recorded by electrocardiographers. It is possible to locate the direction of excitation and recovery by considering that the direction of the event (excitation or recovery) is at right angles to the isoelectric lead (i.e. the lead with equal forces in the positive and negative). This can be demonstrated by forming an equilateral triangle (Einthoven’s triangle) such as in Figure 18.2(a).

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

Nanomaterials ◽  
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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