Textile based electrodes for ECG and EMG measurements

Biopotential signals are an important tool for monitoring our health and thanks to the evolution of technology, they are being increasingly used in several areas. There are however some problems with conventional electrodes such as irritation that need to be surpassed and textile electrodes may represent a good alternative. This paper proposes a design approach for textile based electrodes developed by our research group, in which the construction of the electrodes is based on 3D surface design of weft knitted structures, which increases thickness and allows to improve the permanent contact between electrode and skin, thus contributing for the solution of one of the problems identified by the research community.This work is financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/acceptedVersio

Innovative Wearable Sensors Based on Hybrid Materials for Real-Time Breath Monitoring

This chapter will present the importance of innovative hybrid materials for the development of a new generation of wearable sensors and the high impact on improving patient’s health care. Suitable conductive nanoparticles when embedded into a polymeric or glass host matrix enable the fabrication of flexible sensor capable to perform automatic monitoring of human vital signs. Breath is a key vital sign, and its continuous monitoring is very important including the detection of sleep apnea. Many research groups work to develop wearable devices capable to monitor continuously breathing activity in different conditions. The tendency of integrating wearable sensors into garment is becoming more popular. The main reason is because textile is surrounding us 7 days a week and 24 h a day, and it is easy to use by the wearer without interrupting their daily activities. Technologies based on contact/noncontact and textile sensors for breath detection are addressed in this chapter. New technology based on multi-material fiber antenna opens the door to future methods of noninvasive and flexible sensor network for real-time breath monitoring. This technology will be presented in all its aspects

A Hybrid-Powered Wireless System for Multiple Biopotential Monitoring

Chronic diseases are the top cause of human death in the United States and worldwide. A huge amount of healthcare costs is spent on chronic diseases every year. The high medical cost on these chronic diseases facilitates the transformation from in-hospital to out-of-hospital healthcare. The out-of-hospital scenarios require comfortability and mobility along with quality healthcare. Wearable electronics for well-being management provide good solutions for out-of-hospital healthcare. Long-term health monitoring is a practical and effective way in healthcare to prevent and diagnose chronic diseases. Wearable devices for long-term biopotential monitoring are impressive trends for out-of-hospital health monitoring. The biopotential signals in long-term monitoring provide essential information for various human physiological conditions and are usually used for chronic diseases diagnosis. This study aims to develop a hybrid-powered wireless wearable system for long-term monitoring of multiple biopotentials. For the biopotential monitoring, the non-contact electrodes are deployed in the wireless wearable system to provide high-level comfortability and flexibility for daily use. For providing the hybrid power, an alternative mechanism to harvest human motion energy, triboelectric energy harvesting, has been applied along with the battery to supply energy for long-term monitoring. For power management, an SSHI rectifying strategy associated with triboelectric energy harvester design has been proposed to provide a new perspective on designing TEHs by considering their capacitance concurrently. Multiple biopotentials, including ECG, EMG, and EEG, have been monitored to validate the performance of the wireless wearable system. With the investigations and studies in this project, the wearable system for biopotential monitoring will be more practical and can be applied in the real-life scenarios to increase the economic benefits for the health-related wearable devices

Wearable smart textiles for long-term electrocardiography monitoring : a review

The continuous and long-term measurement and monitoring of physiological signals such as electrocardiography (ECG) are very important for the early detection and treatment of heart disorders at an early stage prior to a serious condition occurring. The increasing demand for the continuous monitoring of the ECG signal needs the rapid development of wearable electronic technology. During wearable ECG monitoring, the electrodes are the main components that affect the signal quality and comfort of the user. This review assesses the application of textile electrodes for ECG monitoring from the fundamentals to the latest developments and prospects for their future fate. The fabrication techniques of textile electrodes and their performance in terms of skin–electrode contact impedance, motion artifacts and signal quality are also reviewed and discussed. Textile electrodes can be fabricated by integrating thin metal fiber during the manufacturing stage of textile products or by coating textiles with conductive materials like metal inks, carbon mate-rials, or conductive polymers. The review also discusses how textile electrodes for ECG function via direct skin contact or via a non-contact capacitive coupling. Finally, the current intensive and promising research towards finding textile-based ECG electrodes with better comfort and signal quality in the fields of textile, material, medical and electrical engineering are presented as a perspective

Thermal protection properties of aerogel-coated Kevlar woven fabrics

This paper investigated the thermal properties of aerogel-coated Kevlar fabrics under both the ambient temperature and high temperature with laser radiation. It is found that the aerogels combined with a Kevlar fabric contribute to a higher thermal insulation value. Under laser radiation with high temperature, the aerogel content plays a vital role on the surface temperature of the fabrics. At laser radiations with pixel time 330 μs, the surface temperatures of the aerogel coated Kevlar fabrics are 400-440°C lower than that of the uncoated fabric. Results also show that the fabric temperature is directly proportional to pixel time. It can be concluded that the Kevlar fabrics coated with silica aerogel provides better thermal protection under high temperature

Analysis and Characterization of Embroidered Textile Strain Sensors for Use in Wearable Mechatronic Devices

Stroke and musculoskeletal disorders affect hundreds of millions of people around the world. To aid in the recovery process of people affected by these conditions, the use of wearable mechatronic devices has been proposed during traditional rehabilitation therapies. However, factor such as rigidity, increased weight, and overall bulkiness have hindered the adoption of these devices in a clinical setting. Therefore, alternative solutions in the form of soft wearable mechatronic devices have been proposed recently. This is due to these devices being lightweight and comfortable, and compliant, which makes them easier to conform to the human body. To achieve such compliance, high emphasis has been placed on the development of soft sensing mechanisms, as they are in charge of collecting information from the device, the environment and user. Among these sensing mechanisms, force and motion sensors have been extensively studied, as they are the simplest to integrate in wearable mechatronic devices. However, the majority of these sensors have been developed using soft materials that are not breathable and can cause skin irritations due to the materials used to fabricate them. For these reasons, textile sensors have been proposed as an alternative. Among these textile solutions, embroidered sensors have shown great potential, as they are relatively simple to manufacture and have high scalability characteristics. Unfortunately, embroidered sensors have the disadvantage of not being stretchable, which is one of the many characteristics of motion and force sensors. To address these issues, this thesis focuses on the design, development, characterization, and performance assessment of embroidered textile strain sensors. To this end, a framework for the development of embroidered textile strain sensors was proposed. This framework included all the necessary steps to design and fabricate these sensors. To achieve the required stretchability of embroidered sensors, a set of customizable parameters were included within this framework. Then, following the guidelines of the proposed framework, a novel embroidered strain sensor was created using a honeycomb pattern. This pattern had two main purposes: a distribution of the axial forces across the walls of the honeycomb design to protect the conductive thread; and the addition of stretchiness to the embroidered sensor. Sensors created using this pattern were embroidered onto an elastic band and then attached to a strain compensation system to increase the stretchability of the sensor further. After 50 stretching cycles, sensors showed good linearity, an average gauge factor of 0.24, an average hysteresis of 36.85% and up to 55.56% working range. This demonstrated the ability of the embroidered sensor to work as a strain sensor, without showing signs of damage and without showing signs of deformation. Lastly, a series of embroidered sensors were fabricated using a Kirigami design. These sensors were created to measure forces under dynamic conditions. Before testing, these sensors were attached to a strain compensation mechanism, which in turn was attached to a force sensing device that served as ground truth for the data collected by the embroidered sensors. The embroidered sensors were tested under three different speed profiles: slow speed, medium speed, and high speed. On each speed profile, each sensor showed high linearity, a low hysteretic behaviour, and relatively good repeatability. These results established the capabilities of the embroidered strain sensors as force sensors that could be used inside soft wearable mechatronic devices

The 3rd International Conference on the Challenges, Opportunities, Innovations and Applications in Electronic Textiles

This reprint is a collection of papers from the E-Textiles 2021 Conference and represents the state-of-the-art from both academia and industry in the development of smart fabrics that incorporate electronic and sensing functionality. The reprint presents a wide range of applications of the technology including wearable textile devices for healthcare applications such as respiratory monitoring and functional electrical stimulation. Manufacturing approaches include printed smart materials, knitted e-textiles and flexible electronic circuit assembly within fabrics and garments. E-textile sustainability, a key future requirement for the technology, is also considered. Supplying power is a constant challenge for all wireless wearable technologies and the collection includes papers on triboelectric energy harvesting and textile-based water-activated batteries. Finally, the application of textiles antennas in both sensing and 5G wireless communications is demonstrated, where different antenna designs and their response to stimuli are presented