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

Abstract

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.

Roll-to-roll fabrication of silver/silver chloride coated yarns for dry electrodes and applications in biosignal monitoring

“…The method used to fabricate Ag/AgCl yarns is a modified setup from previous work 12 . The setup allows for a higher throughput of Ag/AgCl yarn, as well as modifiable process parameters, which allow for accurate control of coating thicknesses and yarn conductance to meet material performance requirements.…”

“…Efforts have been devoted to developing dry electrodes for biosignal monitoring, such as printed Ag/AgCl-based inks on flexible substrates or textiles 4 , 10 . Work by Xu et al 11 and Haddad et al 12 have demonstrated the fabrication of Ag/AgCl based e-textiles comparable with Ag/AgCl solid gel electrodes for biosignal monitoring.…”

“…This work reports a continuous roll-to-roll electrochemical system for the lab scale fabrication of Ag/AgCl-coated multi-filament nylon yarn that has been developed by the authors 12 , electrochemical characterization of the coating process of AgCl on Ag-nylon yarns, design, and performance of embroidered electrodes for ECG measurement, which provide insights into the stability and performance as an electrode material.…”

Bioimpedance Sensors: A Tutorial

“…Plating, dip-coating, physical vapor deposition, polymerization of conducting polymers, knitting, weaving and embroidery, inkjet, screen, and stencil printing are used [168]- [171]. Roll-to-roll electrochemical fabrication of Ag/AgCl coated nylon yearns has been demonstrated [172], and screen and stencil printing and blade coating have been combined for wearable EIT electrode arrays on polyester fabrics [173]. Along with silver, PEDOT:PSS (with additional crosslinkers for improved properties) is playing a prominent role with textile electrodes as well [171], [174].…”

Construction of dense plasmonic hotspots on coarse Ag layer coated nylon fibers for ultrasensitive SERS sensing

“…In particular, metal coated nylon fibers have been broadly applied in wearable sensors, such as strain sensors, 40 conductive resistive sensors, 41 pressure sensors, 42 and biological sensors. 43 In addition, noble metal coated nylon fibers with a rough surface provide the possibility to be used as wearable high-sensitive SERS substrates due to the facilitation of building dense plasmonic hotspots. In this work, coarse silver (Ag) layer coated nylon fibers (NFs) with twisted spiral structure are used to load gold (Au) nanoparticles (NPs) to fabricate ultrasensitive SERS substrate (denoted as Au NP@Ag/NF) in a relatively simple and low-cost technique.…”