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Cardiovascular diseases are the leading cause of lethal issues worldwide. The most effective way to combat these diseases is the real-time monitoring of the electrocardiogram (ECG) that reflects the electrical signals generated by the heart cells. So far, the ECG is recorded by using the cutaneous conventional medical electrodes (Ag/AgCl). These electrodes are not adapted for long-term use as they are not fully integrated into underwear and generally can provoke skin irritation, because of the ionic gel that serves to reduce the impedance of the electrode/ skin interface. The first part of this paper concerns the design and realization by embroidery of three different patterns of conductive tracks that could be adopted as connection lines between an electronic module and ECG electrodes. In order to make these conductive tracks washable, two encapsulation methods have been investigated. The reliability of the developed conductive tracks and encapsulation methods has been analyzed. The second part of this study is focused on the development of washable embroidered ECG bands operating without any ionic gel as alternatives to medical electrodes (Ag/AgCl). The acquisition of ECG signals has been carried out on 3 female and 6 male healthy subjects aged between 25 and 55 years. In the last stage of this paper, we explore the ECG signal in static condition, the spectral power density of the ECG signal, the signal-to-noise ratio (SNR) of ECG electrodes before and after 50 washing cycles.

The improvement of human health condition is an important objective that remains relevant since the origin of human being. Currently, cardiovascular diseases are the first cause of death worldwide. For this reason, permanent real-time monitoring of heart activity (Electrocardiogram: ECG), its analysis and alerting of concerned person is a solution to decrease the death toll provoked by heart diseases. ECG signal of medical quality is necessary for permanent monitoring and accurate heart examining. It can be obtained from instrumented underwear only if it is equipped with high quality, flexible textile based electrodes guaranteeing low contact resistance between the skin and them. This work is therefore devoted to the design and test of wearable textile embroidered bands following defined protocol for ECG long-term monitoring. These bands were investigated in three configurations: band without any adding layer to protect lines between electrodes and the connector, band with lines protected by simple yarn, band with lines protected with thermoplastic polyurethane (TPU). Bands were worn around chest by healthy subjects in a sitting position and ECG signals were acquired by an Arduino-based device and assessed. Washability tests of connected underwear were carried out over 50 washing cycles in a domestic machine and by using a commercial detergent. Influence of encapsulation process on the electrical properties of textile electrodes during repetitive washing process has also been investigated and analyzed. All the ECG signals acquired and recorded have been reviewed by a cardiologist in order to validate their quality required for accurate diagnosis.

A development of washable PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) polyamide textile-based electrodes is an interesting alternative to the traditional Ag/AgCl disposable electrodes, usually used in clinical practice, helping to improve medical assessment and treatment before apparition or progress of patients&rsquo, cardiovascular symptoms. This study was conducted in order to determine whether physical properties of PEDOT:PSS had a significant impact on the coated electrode&rsquo, s electrocardiogram (ECG) signal quality, particularly after 50 washing cycles in a domestic laundry machine. Tests performed, included the comparison of two PEDOT:PSS solutions, in term of viscosity with emphasis on wetting tests, including surface tension and contact angle measurements. In addition, polyamide textile fabrics were used as substrate to make thirty electrodes and to characterize the amount of PEDOT:PSS absorbed as a function of time. The results showed that surface tension of PEDOT:PSS had a significant impact on the wetting of polyamide textile fabric and consequently on the absorbed amount. In fact, lower values of surface tension of the solution lead to low values contact angles between PEDOT:PSS and textile fabric (good wettability). Before washing, no significant difference has been observed among signal-to-noise ratios measured (SNR) for coated electrodes by the two PEDOT:PSS solutions. However, after 50 washing cycles, SNR decreased strongly for electrodes coated by the solution that had low viscosity, since it contained less solid contents. That was confirmed by scanning electron microscopy images (SEM) and also by analyzing the color change of electrodes based on the calculation of CIELAB color space coordinates. Moreover, spectral power density of recorded ECG signals has been computed and presented. All cardiac waves were still visible in the ECG signals after 50 washing cycles. Furthermore, an experienced cardiologist considered that all the ECG signals acquired were acceptable. Accordingly, our newly developed polyamide textile-based electrodes seem to be suitable for long-term monitoring. The study also provided new insights into the better choice of PEDOT:PSS formulation as a function of a specific process in order to manufacture cheaper electrodes faster.

Long-term monitoring of the electrical activity of the heart helps to detect the presence of potential dysfunctions, enabling the diagnosis of a wide range of cardiac pathologies. However, standard electrodes used for electrocardiogram (ECG) acquisition are not fully integrated into garments, and generally need to be used with a gel to improve contact resistance. This article is focused on the development of washable screen-printed cotton, with and without Lycra, textile electrodes providing a medical quality ECG signal to be used for long-term electrocardiography measurements. Several samples with different Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) concentrations were investigated. Silver-plated knitted fabric electrodes were also used for comparison, within the same process of ECG signal recording. The acquisition of ECG signals carried out by a portable medical device and a low-coast Arduino-based device on one female subject in a sitting position. Three textile electrodes were placed on the right and left forearms and a ground electrode was placed on the right ankle of a healthy female subject. Plastic clamps were applied to maintain electrodes on the skin. The results obtained with PEDOT:PSS used for electrodes fabrication have been presented, considering the optimal concentration required for medical ECG quality and capacity to sustain up to 50 washing cycles. All the ECG signals acquired and recorded, using PEDOT:PSS and silver-plated electrodes, have been reviewed by a cardiologist in order to validate their quality required for accurate diagnosis.

Electrode-skin impedance is strongly influencing the quality of electrocardiograms (ECG) signals. Lower impedance results in stronger signals as well as less noise disturbance. In this study, we determine contact impedance between the skin and a flexible textile electrode based on a modified poly (3,4-ethylenedioxythiophene) :poly (styrenesulfonate) (PEDOT:PSS) coating, developed in our laboratory. Cotton knitted fabrics were used to test the measurement technique. For each measurement, a pair of same electrodes in terms of size was used. To obtain a better understanding of the obtained impedance results, the contact impedance was simulated by an electronic model and hence electrode circuit model components were calculated. In order to realize a comparative study, conventional medical electrodes silver/silver chlorides (Ag/ AgCl) were also assessed. The measurement technique can be applied to any other type of electrode in contact with a skin.