Carbon-Based Textile Dry and Flexible Electrodes for ECG Measurement

Abstract

The electrocardiogram signals of humans heart are usually estimated using wet silver/silver chloride (Ag/AgCl) electrodes. These wet electrodes cannot be reused and require extra skin preparation (application of conductive gel) which may cause skin aggravation in long run, and also during measurement of the electrocardiogram signals, it enhances a common-mode noise due to loose contact with skin. Therefore, this paper proposes the design, fabrication and testing of dry electrodes for recording the ECG signals which overcomes the problems associated with wet Ag/AgCl electrodes. These electrodes are adaptable, biocompatible, reusable and conduction gel-free. Carbon paste was coated on a flexible circular polymer substrate of different diameters (E1-20 mm, E2-16 mm, E3-1 mm) to prepare dry Electrocardiogram electrodes. The conducting performance of E1, E2, E3 and Ag/AgCl electrodes was analysed by measuring the skin–electrode impedance and observed that the skin impedance is inversely proportion to the electrodes area. The skin–electrode impedance results concluded that the electrodes with the largest diameter exhibited better performance in terms of the conductivity for acquisition of quality electrocardiogram signals. The skin impedance of dry electrodes (E1, E2, E3) and Ag/AgCl electrodes was measured and compared at a common frequency of 10 Hz. The raw electrocardiogram signal detected should be pre-processed through various signal processing units to overcome the high level noise. The aim of this work is to design dry electrodes and also pre-process the signals recorded by the dry electrocardiogram electrodes which can be further used for portable applications. Also, this paper presents the working of dry electrodes and its comparison with wet Ag/AgCl electrodes for medical and research purposes.