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In this study, polymeric/metallic yarns were fabricated by using the micrometric copper multifilament and the polymer multifilament to create electrically conductive, thin, flexible composite yarn structures. The main aim is to realize the circuit board by using fabricated conductive yarns in the needle position of the embroidery machine and to integrate electronic components on textile structures by the soldering process. In the embroidery machine, the usage of the yarn in the needle gives a chance to create a tailored design according to the specified application. Mechanical and electrical properties of fabricated yarns were investigated. Meanwhile, a benchmark test has been done by using other commercial conductive yarns. Their embroidery performances were tested by investigating the possible harms during the stitching process. Finally, several embroidered circuit boards have been realized to show the versatility of fabricated yarns for different circuit designs.

The textile-based electrochromic (EC) display which has been developed and presented in this article, is very compact, robust, flexible, stable, efficient, economical, and inclined to biocompatibility. The developed textile display is having only three-layer over conventional seven layers patented electrochromic structures. It is also very efficient, as it can perform its functionality even after 2500 cycles of a run and 1500 times of bending. The innovative and simplified structure of the EC device has been developed with only 3 layers, including the displaying electrode, the electrolyte container, and the counter electrode. The conductive polymer PEDOT:PSS used here as a conductive and electrochromic material, is coated on the textile substrate to perform as one side of the electrode for the asymmetric arrangement of the electrochromic device. The experiment has also been done to find out the best possible textile fabric to serve as the optimal electrochromic container. The biocompatible H3PO4 gel drenched in the semi-permeable membrane has been used as an ion transfer medium for the electrochromic display. This biocompatible ion transfer medium is sandwiched in between the electrochromic displaying electrode (PEDOT:PSS coated on fabric) and aluminum sheet (counter electrode) for making this handmade crude electrochromic display. The investigation of the EC display functioning has been observed through cyclic voltammetry within the life cycle run. The performance of the device has also been investigated in real-life conditions, by providing just ±2.0 V DC power. The other possibility is shown in our article to deposit the PEDOT:PSS compound on the textile substrate was to coat directly the yarns and then to use them into the weaving process to produce the displaying electrode. By this technique, it would also be possible to develop hybrid displays made of structures containing knitted or woven side-emitting optical fibers and our electrochromic display structure, locally.

The development of e-textiles necessitates the creation of highly conductive inks that are compatible with precise inkjet printing, which remains a key challenge. This work presents an innovative, syringe-based method to optimize a novel bio-sourced silver ink for inkjet printing on textiles. We investigate the relationships between inks’ composition, rheological properties, and printing behavior, ultimately assessing the electrical performance of the fabricated circuits. Using Na–alginate and polyethylene glycol (PEG) as the suspension matrix, we demonstrate their viscosity depends on the component ratios. Rheological control of the silver nanoparticle-laden ink has become paramount for uniform printing on textiles. A specific formulation (3 wt.% AgNPs, 20 wt.% Na–alginate, 40 wt.% PEG, and 40 wt.% solvent) exhibits the optimal rheology, enabling the printing of 0.1 mm thick conductive lines with a low resistivity (8 × 10−3 Ω/cm). Our findings pave the way for designing eco-friendly ink formulations that are suitable for inkjet printing flexible antennas and other electronic circuits onto textiles, opening up exciting possibilities for the next generation of E-textiles.

Abstract An original fully textile combiner is proposed to power supply sensors close to a body with only one centralized source of energy like a smartphone, for instance. A solution is provided for taking into account the requirements of an industrial production process that need to minimize needle movements during an embroidery process. Moreover, the paper shows how to support several wireless power transmission standards that already exist, i.e. NFC and A4WP, or will exist to satisfy the tremendous needs of energy for distributed systems in the IoT domain. In this paper, a new textile-based flexible wireless system enabling communication and energy harvesting is proposed. Analytical, numerical, and experimental studies have been conducted to demonstrate that the structure has two resonant frequencies at 6.8 MHz and 13.6 MHz, which make it suitable for NFC and A4WP standards. Moreover, the losses caused by the system are 2.76 dB and 1.91 dB for A4WP and NFC, respectively. The results are successively presented to highlight the specificities of such textile multi-coils combiners. A method for gaining a resonant structure without any solid electronic component is explained.

The performance of bulletproof vests is mainly based on the energy absorption capacity of the flexible fibrous reinforcements. To understand the in situ behaviour of these textile structures during a ballistic impact, we find the use of sensor yarns integrated into these fibrous reinforcements to be a non-invasive and reliable solution. Measurements of the dynamic deformation of the sensor yarns will provide a new and useful source of information. The design and manufacturing stages of a sensor yarn, made with the same structural yarns of the fabric, are detailed successively. Then, different batches of sensor yarns were designed, and electromechanical tensile tests were performed in quasi-static mode. These experiments provide encouraging results for the measurement of the deformation of a textile structure subject to a dynamic impact.

Abstract Smart and e-textiles have nowadays an important increasing place in the garment industry. The rise of embedded telecommunications, especially smartphones in our pocket, enables us to provide a power source and a wireless link for smart textiles. The main issue is to develop garments able to receive power from smartphones and communicate with them without flexibility and comfort constraints bound to embedded solid-state electronic components. Consequently, this article aims to develop a fully textile NFC combiner to transfer data and power between a smartphone and sensors without any electronic components. It precisely describes textile NFC multiple combiners composed of textile NFC antennas linked by two-wire transmission lines. Also, theoretical analysis, simulations, and experiments have been conducted to adapt the resonant frequency of such structures to the NFC technology (13.56 MHz). Finally, our article generalizes textile NFC combiner resonant frequency equations for multiple combiners with any number of antennas.

In this work, a sensor yarn based on a natural sisal yarn containing a non-electro-conductive core impregnated with PVA polymer and coated by PEDOT:PSS polymer as an electro-conductive sheath was investigated. The main objectives include the development of this new sensor yarn as a first step. Then, we look towards the insertion of this sensor yarn into different woven structures followed by the monitoring of the mechanical behaviour of composite materials made with these fibrous reinforcements. The combined effect of the structural geometry and the number of PEDOT:PSS coating layers on the properties of the sensor yarns was investigated. It was found that the number of PEDOT:PSS coating layers could strongly influence the electromechanical behaviours of the sensor yarns. Different methods of characterization were employed on strain-sensor yarns with two and four coating layers of PEDOT:PSS. The piezo-resistive strain-sensor properties of these selected coating layers were evaluated. Cyclic stretching-releasing tests were also performed to investigate the dynamic strain-sensing behavior. The obtained results indicated that gauge factor values can be extracted in three strain regions for two and four coating layers, respectively. Moreover, these strain-sensor yarns showed accurate and stable sensor responses under cyclic conditions. Furthers works are in progress to investigate the mechanism behind these first results of these sisal fibre-based sensors.

E-textiles reveal a new and hybrid sector of the industry that is created by the integration of electronic components or textile-based electronics in our daily life textile products. They are facing problems in terms of washability, reliability, and user acceptance. This manuscript explains the mechanical stresses acting during the washing process and their impact on e-textile systems. Different washing programs were investigated in terms of total process duration. This washing process duration is mainly divided into three diverse washing actions: low-speed rotation, high-speed rotation, and stop time. This investigation was performed to highlight the importance of the washing actions and their percentages in the total washing process. A piece of fabric with a flexible PCB (printed circuit board), equipped with an accelerometer with a Bluetooth communication device and a microcontroller, was placed in the washing machine to analyze the movement of fabric provoked by washing stresses. The PCB was used for fabric movements recording to determine the impact of mechanical stress on e-textile systems during the washing process. From the video analysis, it was concluded that the duration of the low-speed and high-speed rotation actions should be privileged comparing to the duration of the whole washing process. A power spectral density (PSD) analysis based on the accelerometer outputs was realized. Mechanical stresses at different frequencies were identified. Based on this analysis, it could be possible to improve the protocols of mechanical tests (Martindale and pilling box) used to simulate the mechanical stress applied to e-textile systems during the washing process.

Reliability and washability are major hurdles facing the e-textile industry nowadays. The main fear behind the product’s rejection is the inability to ensure its projected life span. The durability of e-textiles is based on an approximate lifetime of both the electronics and textiles integrated into the product. A detailed analysis of the wash process and the possibility of predicting product behavior are key factors for new standards implementation. This manuscript is focused on the washability issues of different types of woven, knitted, and embroidered, textile-based ECG electrodes. These electrodes are used without the addition of any ionic gel to the skin to reduce impedance. They were subjected to up to 50 wash cycles with two different types of wash processes, and changes in surface resistance, as well as the quality of ECG waves, were observed To investigate the wash damages in detail, the proposed mechanical (Martindale and Pilling box) and chemical test methods were investigated. The electrodes which increased resistance after washing showed the same trend in the proposed test methods. Copper-based electrodes suffered the most severe damage and increased resistance, as was also visible in an SEM analysis. These proposed test methods can be used to predict robustness behavior without washing.

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’ cardiovascular symptoms. This study was conducted in order to determine whether physical properties of PEDOT:PSS had a significant impact on the coated electrode’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.

The quality of fibrous reinforcements used in composite materials can be monitored during the weaving process. Fibrous sensors previously developed in our laboratory, based on PEDOT:PSS, have been adapted so as to directly measure the mechanical stress on fabrics under static or dynamic conditions. The objective of our research has been to develop new sensor yarns, with the ability to locally detect mechanical stresses all along the warp or weft yarn. This local detection is undertaken inside the weaving loom in real time during the weaving process. Suitable electronic devices have been designed in order to record in situ measurements delivered by this new fibrous sensor yarn.

A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%.

A medical quality electrocardiogram (ECG) signal is necessary for permanent monitoring, and an accurate heart examination can be obtained from instrumented underwear only if it is equipped with high-quality, flexible, textile-based electrodes guaranteeing low contact resistance with the skin. The main objective of this article is to develop reliable and washable ECG monitoring underwear able to record and wirelessly send an ECG signal in real time to a smart phone and further to a cloud. The article focuses on textile electrode design and production guaranteeing optimal contact impedance. Therefore, different types of textile fabrics were coated with modified poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) in order to develop and manufacture reliable and washable textile electrodes assembled to female underwear (bras), by sewing using commercially available conductive yarns. Washability tests of connected underwear containing textile electrodes and conductive threads were carried out up to 50 washing cycles. The influence of standardized washing cycles on the quality of ECG signals and the electrical properties of the textile electrodes were investigated and characterized.

The aim of this study was to develop and optimize a reproducible flexible sensor adapted to thin low-density polyethylene (LDPE) films and/or structures to enable their deformation measurements. As these deformations are suspected to be weak (less than 10%), the developed sensor needs to be particularly sensitive. Moreover, it is of prime importance that sensor integration and usability do not modify the mechanical behavior of its LDPE substrate. The literature review allowed several materials to be investigated and an elastomer/intrinsically conductive polymer PEDOT:PSS (CleviosTM) filled composite was selected to simultaneously combine mechanical properties and electrical conductivity. This composite (made of PEDOT:PSS and silicone Bluesil®) presented satisfying compatibilities with piezoresistive effects, negative temperature performances (in a range from −60 °C to 20 °C), as well as elongation properties (until the elastic limit of the substrate was reached). The method used for creating the sensor is fully described, as are the optimization of the sensor manufacture in terms of used materials, the used amount of materials where the percolation theory aspects must be considered, the adhesion to the substrate, and the manufacturing protocol. Electromechanical characterization was performed to assess the gauge factor (K) of the sensor on its substrate.