Integration and embedding of vital signs sensors and other devices into textiles

The development of ubiquitous vital sign monitoring has become a very up-to-date research theme for many academics and industrial companies in the last years. With new materials and integration techniques, it is possible to implement vital sign monitoring in an economic manner, directly into textile products. This unobtrusive presence of sensors is especially important for the monitoring of children or elderly people. This paper focuses on two aspects of sensor integration: Integration of off-the-shelf electronic components, and the use of the textile material itself as sensor, or in general as an electrically active element presenting some exploratory work in the integration of electronic devices into textiles. The main objective was to reproduce and improve on previous work presented by other authors, and foster possibilities of developing garments for vital sign monitoring with immediate industrial and economic feasibility. The use of standard production techniques to produce textile-based sensors, easily integrated into garments and with mass-market potential, is one of the important motivations for this work

Study of vital sign monitoring with textile sensors in swimming pool environment

This paper presents the results of a series of experiments aiming at the optimisation of vital sign monitoring using textile electrodes to be used in a swimsuit. The swimsuit will integrate sensors for the measurement of several physiological and biomechanical signals; this paper will focus on ECG and respiratory movement analysis. The data obtained is mainly intended to provide tools for evaluation of high-performance swimmers, although applications can be derived for leisure sports and other situations. A comparison between electrodes based on different materials and structures, behaviour in dry and wet environments, as well as the behavior in different extension states, will be presented. The influence of movement on the signal quality, both by the muscular electrical signals as well as by the displacement of the electrodes, will be discussed. The final objective is the integration of the electrodes in the swimsuit by knitting them directly in the suit’s fabric in a seamless knitting machineFundação para a Ciência e a Tecnologia (FCT) - PTDC/EEAELC/70803/200

Deposition of conductive materials on textile and polymeric flexible substrates

This paper describes the study, analysis and selection of textile and similar materials to be used as flexible substrates for thin conductive film deposition, in the context of integrating electronics into textiles. Kapton® polyimide was chosen as reference substrate material, was characterized regarding mechanical and electrical properties and was used as a basis for a comparison with several textile substrates. Samples were fabricated using physical vapour deposition (thermal evaporation) to deposit a thin layer of aluminium on top of Kapton and textile substrates. The measurement of electrical resistance of the thin aluminum films was carried out using the Kelvin method. To characterize the mechanical behaviour of the substrate and aluminum film, several mechanical tests were performed and results were compared between Kapton and these textile materials. The chemical composition of the textile substrates and aluminum films as well as the continuity of the films was characterized. This selection process identified the material that was closer to the behaviour of polyimide, a flexible, but non-elastic woven textile coated on both sides with PVC.FEDER funds in COMPETE program and by FCT, in the project FCOMP-01-0124-FEDER-02267

Artifact reduction in multichannel ECG recordings acquired with textile electrodes

Textile electrodes integrated into clothes are an innovative approach for mobile ECG monitoring. However, the lack of electrode fixation on the skin causes high susceptibility to artifacts due to movements and changing electrochemical characteristics of the textile electrodes. In this paper we compare different artifact removal approaches concerning their efficiency in realistic multichannel ECG recordings acquired with textile electrodes. We employed Principal Component Analysis (PCA) and Independent Component Analysis (ICA) in time and frequency domain using FastICA and Temporal Decorrelation Source Separation (TDSEP), respectively. Using textile electrodes comprising silver-coated fibers, five Einthoven-I-leads were acquired during walking, running and extensive breathing. Horizontally aligned electrodes each located on the left and right side of the shoulders, the chest and the back obtain the ECG signals. A reference signal was recorded using self-adhesive Ag/AgCl electrodes placed at the inner forearms enabling calculation of the correlation coefficient and the R-peak detection error. The methods using ICA enhance ECG recordings acquired with textile electrodes for all test conditions. TDSEP in the time domain obtains the best results and successfully removes artifacts in recordings of extensive breathing and walking. The results during running show considerable improvements but no complete artifact separation. In conclusion, ICA represents a promising approach for artifact reduction in multichannel ECG recordings acquired with textile electrodes

Textile sensors for ECG and respiratory frequency on swimsuits

Swimming constitutes one of the most demanding sports regarding technique. Years of training are necessary to master each one of the four styles. An important improvement and help for trainers would be a swimsuit that could provide information during training. This paper presents the research undertaken to develop textile sensors that will be used in a swimsuit. This paper will address ECG and respiratory frequency sensors and respective signals. The behaviour of the proposed sensors in different conditions (dry and wet environments) will be presented and discussed. The influence of movement on the signal quality and further interpretation, both by the muscular electrical signals as well as by the displacement of the electrodes, will be addressed. Other very important issue in swimming is drag. One approach that can reduce total drag consists in using compression. However, compressed fabrics will most likely modify the textile sensors’Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EEA-ELC/70803/200

Graphene textile smart clothing for wearable cardiac monitoring

Wearable electronics is a rapidly growing field that recently started to introduce successful commercial products into the consumer electronics market. Employment of biopotential signals in wearable systems as either biofeedbacks or control commands are expected to revolutionize many technologies including point of care health monitoring systems, rehabilitation devices, human–computer/machine interfaces (HCI/HMIs), and brain–computer interfaces (BCIs). Since electrodes are regarded as a decisive part of such products, they have been studied for almost a decade now, resulting in the emergence of textile electrodes. This study reports on the synthesis and application of graphene nanotextiles for the development of wearable electrocardiography (ECG) sensors for personalized health monitoring applications. In this study, we show for the first time that the electrocardiogram was successfully obtained with graphene textiles placed on a single arm. The use of only one elastic armband, and an “all-textile-approach” facilitates seamless heart monitoring with maximum comfort to the wearer. The functionality of graphene textiles produced using dip coating and stencil printing techniques has been demonstrated by the non-invasive measurement of ECG signals, up to 98% excellent correlation with conventional pre-gelled, wet, silver/silver-chloride (Ag / AgCl) electrodes. Heart rate have been successfully determined with ECG signals obtained in different situations. The system-level integration and holistic design approach presented here will be effective for developing the latest technology in wearable heart monitoring devices

Validation of two types of textile electrodes for electrocardiography and electromyography measurement applications

Tese de mestrado. Engenharia Biomédica. Faculdade de Engenharia. Universidade do Porto. 201

Capacitive electrodes for measuring bioelectric signals

Kapazitive Elektroden ermöglichen eine einfache Messung des Elektrokardiogramms (EKG) und Elektroenzephalogramms (EEG). Sie koppeln im Gegensatz zu herkömmlich verwendeten galvanischen Elektroden das Biosignal über einen isolierten kapazitiven Kontakt zum Körper aus. Der Fokus dieser Arbeit liegt auf der Charakterisierung des Übertragungsverhaltens dieser kapazitiven Elektroden und der praktischen Anwendung im Bereich der Routine-Diagnostik und spezieller Interface-Systeme am Beispiel des Brain-Computer Interfaces. Das im Rahmen dieser Arbeit entwickelte portable EKG-System ermöglicht die Messung mit 15 Elektroden, selbst durch Kleidung hindurch, und verbindet die klassische EKG-Messung mit einem einfachen Zugang zu komplexen räumlichen Darstellungen der Herzaktivität in Form von Body-Surface-Potential-Maps. Das Verfahren wird direkt mit etablierten Verfahren verglichen und anhand realer Patientendaten validiert. Dazu wurden Messungen in klinischer Umgebung durchgeführt. Die Ergebnisse zeigen eine gute Übereinstimmung der Messungen zwischen kapazitivem und galvanischem Aufbau. Durch die spezielle Anordnung der Elektroden im verwendeten System kann eine deutliche Vereinfachung der EKG-Messung realisiert werden. Die in dieser Arbeit durchgeführte elektrische Charakterisierung der Elektroden und die Beschreibung der Rauschprozesse ermöglicht ein besseres Verständnis der besonders für das EEG benötigten höheren Messempfindlichkeit. Um diese praktisch nachzuweisen, bzw. die Grenzen des Systems aufzuzeigen, wird der Aufbau eines kapazitiven 28-Kanal Helmsystems beschrieben, welches zusammen mit der ebenfalls entwickelten analogen und digitalen Signalverarbeitung EEG-Messungen ermöglicht. Gezeigt werden Messungen der Alpha-Aktivität und visuell evozierter Potentiale. Letztere Signale werden zusätzlich in einem speziellen Aufbau zur Realisierung eines kapazitiven Brain-Computer Interfaces verwendet und damit beispielhaft eine Steuerung eines Modellfahrzeugs demonstriert.Capacitive electrodes provide an easy access to bioelectric signals in the field of electrocardiography (ECG) and electroencephalography (EEG). They are based on a capacitive coupling between the electrode and the body; in contrast to the conventionally used galvanic electrodes they are isolated from the body. So capacitive electrodes do not require a direct electrical contact to the skin. This work focuses on the characterization of the transfer function and the noise behavior of the capacitive electrodes and the practical application of this measurement in routine diagnosis and specific interface systems, such as Brain-Computer Interfaces. The development of a portable ECG system is described, enabling the measurement of the ECG with 15 electrodes through clothing. This system combines the classical ECG measurement with complex spatial representations of the cardiac activity called body surface potential mapping. The procedure is directly compared with established systems and real patient data are presented. The results show a high correlation between measurements of the capacitive and galvanic system. The special arrangement of electrodes used in the system greatly simplifies the ECG measurement. The electrical characterization of the electrodes and in particular the description of the noise behavior is evaluated for measuring brain activity because the EEG needs a higher sensitivity. To demonstrate this in practice and also show the limitations of this approach, the construction of a capacitive 28-channel EEG helmet is described. In combination with a developed analog and digital signal processing unit, EEG measurements are possible with this helmet. Measurements of alpha activity and visually evoked potentials are presented. These visual evoked potentials are also used in a special system for the implementation of a capacitive Brain-Computer Interface. The control of a RC car is represented to demonstrate the function of this Brain-Computer Interface