3D‐Knit Dry Electrodes using Conductive Elastomeric Fibers for Long‐Term Continuous Electrophysiological Monitoring

Abstract

Recent advances in telemedicine and personalized healthcare have motivated new developments in wearable technologies targeting continuous monitoring of biosignals. Common limitations of wearables for continuous monitoring include durability and breathability of their biopotential electrodes. This paper tackles this challenge by proposing flexible, breathable, and washable dry textile electrodes made of conductive elastomeric filaments (CEFs). First, candidate CEF fibers are characterized. Using an industrial knitting machine, CEF fibers are then directly knitted into textile electrodes. To assess their performance in more realistic circumstances, smart garments with textile electrodes are knitted. Electrocardiograms (ECGs) are acquired using an underwear garment and electrooculograms (EOGs) are acquired using a headband. ECGs and EOGs with textile electrodes are found to have comparable fidelity to that of the gold standard gel electrodes. CEF electrodes are also resistant to repeated wash and dry cycles (30×) and continue to acquire high‐fidelity biosignals. Smart underwear garments are also used to perform continuous ECG measurements in five participants over 24 h of unrestricted daily activities. Results demonstrate the success of these garments in performing high fidelity continuous ECG monitoring. Collectively, these results present CEF electrodes as a promising scalable solution to the challenges of wearable technologies for long‐term continuous electrophysiological monitoring applications.

Textile‐Integrated Liquid Metal Electrodes for Electrophysiological Monitoring

“…A typical drawback of many textile-based electrodes is that they can't reach the level of conformity needed to provide significant interfacing with the skin before degrading due to the strain imposed to the electrode from the compressive textile. [45,46] For example, dry electrodes using conductive materials such as Ag/AgCl, [13] CNTs, [9] PEDOT:PSS, [45] Ag, [42,46] and carbon black [47] exhibit normalized impedances (impedance multiplied by electrode sensing area) at 100 Hz of ≈566, 424, 800, 283, and 400 kΩ cm 2 , respectively (see Figure S1a, Supporting Information). TILEs show normalized impedance values of ≈100 kΩ cm 2 at 100 Hz, and provide lower impedance values in the frequency range between 100 and 1000 Hz compared to all other textile based electrodes, even showing comparable performance values to PEDOT:PSSS composite [20] and Ag-In-Ga skin-based electrodes.…”

Breathable Electronic Skins for Daily Physiological Signal Monitoring

“…Eskandarian et al . used conductive elastomeric filaments to realize a three-dimensional (3D) conductive e-skin with an industrial-scale knitting machine [ 30 ]. As shown in Fig.…”

“…2 Categories Types Breathability Materials Fabrication Methods Refs. ECG electrodes Moisture-wicking and antibacterial e-skin Water vapor transmission rate (WVT) ~ 70% Dual-gradient poly (ionic liquid) nanofibers Electrospinning [ 29 ] 3D conductive textile e-skin 20 g m −2 h −1 Conductive elastomeric melt-spun filaments Industrial-scale knitting machine [ 30 ] Substrate-free e-skin hardly affects skin perspiration Laser-scribed graphene Sacrificial layer process [ 31 ] EOG electrodes Tattoo-like e-skin Breathable CVD graphene Sacrificial layer process [ 36 ] Textile-based e-skin Breathable Graphene-coated commercial fabrics Dip coating graphene oxide on fabrics and reducing [ 19 , 37 ] Soft-fabric-based e-skin Breathable 20% silver and 80% polyamide, sponge package Dip coated silver on the sponge [ 38 ] EMG electrodes All-nanofiber-based e-skin 1748.09 g m −2 d −1 HPAN, PU, and AgNWs Electrospinning and vacuum filtration [ 43 ] …”

“…If the ECG e-skin electrode can adopt the woven structure like clothing, it can not only meet the requirements of breathability and durability but also be suitable for integration with daily clothing to achieve long-term wearable health monitoring. Eskandarian et al used conductive elastomeric filaments to realize a three-dimensional (3D) conductive e-skin with an industrialscale knitting machine [30]. As shown in Fig.…”

Advances in Materials, Sensors, and Integrated Systems for Monitoring Eye Movements

“…To overcome the disadvantages of the previous fabric electrodes, Eskandarian et al [ 90 ] introduced 3D-Knit fabric-type electrodes based on conductive elastomeric filaments (CEFs), which are flexible, breathable, and washable, as shown in Figure 3 d. The conductive elastomeric materials are knitted or weaved to be electrodes, and the fabric electrodes also can be integrated into the general garment. This unique combination of fabric-type electrodes and garments enables one to monitor electrophysiological signals.…”