Functional garments for physiological sensing purposes have been utilized in several disciplines i.e. sports, firefighting, military and medical. In most of the cases textile electrodes (Textrodes) embedded in the garment are employed to monitor vital signs and other physiological measurements. Electrical Bioimpedance (EBI) is a non-invasive and effective technology that can be used for detection and supervision of different health conditions. In some specific applications such as body composition assessment EBIS has shown encouraging results proving good degree of effectiveness and reliability. In a similar way Impedance Cardiography (ICG) is another modality of EBI primarily concerned with the determination of Stroke Volume SV, indices of contractility, and other aspects of hemodynamics. EBI technology in the previously mentioned modalities can benefit from a integration with a garment; however, a successful implementation of EBI technology depends on the good performance of textile electrodes. The main weakness of Textrodes is a deficient skin-electrode interface which produces a high degree of sensitivity to signal disturbances. This sensitivity can be reduced with a suitable selection of the electrode material and an intelligent and ergonomic garment design that ensures an effective skin-electrode contact area. This research work studies the performance of textile electrodes and garments for EBI spectroscopy for Total Body Assessment and Transthoracic Electrical Bioimpedance (TEB) for cardio monitoring. Their performance is analyzed based on impedance spectra, estimation of parameters, influence of electrode polarization impedance Zep and quality of the signals using as reference Ag/AgCl electrodes. The study includes the analysis of some characteristics of the textile electrodes such as conductive material, skin-electrode contact area size and fabric construction. The results obtained in this research work present evidence that textile garments with a dry skinelectrode interface like the ones used in research produce reliable EBI measurements in both modalities: BIS for Total Body Assessment and TEB for Impedance Cardiography. Textile technology, if successfully integrated, may enable the utilization of EBI in both modalities and consequently implementing wearable applications for home and personal health monitoring.

Background/Objectives:Functional garments for physiological sensing purposes have been used in several disciplines, that is, sports, firefighting, military and medicine. In most of the cases, textile electrodes (textrodes) embedded in the garment are used to monitor vital signs and other physiological measurements. Electrical bioimpedance (EBI) is a non-invasive and effective technology that can be used for the detection and supervision of different health conditions.EBI technology could make use of the advantages of garment integration; however, a successful implementation of EBI technology depends on the good performance of textrodes. The main drawback of textrodes is a deficient skin-electrode interface that produces a high degree of sensitivity to signal disturbances. This sensitivity can be reduced with a suitable selection of the electrode material and an intelligent and ergonomic garment design that ensures an effective skin-electrode contact area.Subjects/Methods:In this work, textrode functional straps for total right side EBI measurements for body composition are presented, and its measurement performance is compared against the use of Ag/AgCl electrodes. Shieldex sensor fabric and a tetra-polar electrode configuration using the ImpediMed spectrometer SFB7 in the frequency range of 3-500 kHz were used to obtain and analyse the impedance spectra and Cole and body composition parameters.Results:The results obtained show stable and reliable measurements; the slight differences obtained with the functional garment do not significantly affect the computation of Cole and body composition parameters.Conclusions:The use of a larger sensor area, a high conductive material and an appropriate design can compensate, to some degree, for the charge transfer deficiency of the skin-electrode interface.

Introduction: After several years of progresses in textile technology and wearable measurement instrumentation, applications of wearable textile-electronics systems are arising providing a stable background for commercial applications. So far, the available commercial solutions are centered on fitness applications and mostly based in the acquisition of heart rate through Textile Electrodes (Textrodes) based on metallic threads or on conductive rubber compounds. Methods and Materials: In this work a novel material approach is presented to produce Textrodes for acquisition of Electrocardiographic (ECG) signals using a conductive polypropylene (PP1386 from Premix, Finland) polymer material. The polymer was film extruded into thin films, and used as such in the Textrode. Conductive Polymer Films (CPF) have been used to produce Textrodes, and its measurement performance has been compared with the ECG signals obtained with commercial Textrode fabrics and conventional Ag/AgCl electrodes. In order to set up the same measurement conditions, a chest strap tailored to host the testing electrodes has been used. Results: The close resemblance of the ECG acquired with the textile fabric electrodes, the Ag/AgCl electrodes and the PP1386 CPF electrodes suggest that the Polymer Electrodes PP1386 are a feasible alternative to the current textile fabrics that use silver thread as conductive material and also to conductive rubber material. Discussion & Conclusion: The availability of the Conductive Polymer Electrode PP1386 in a film form allows the manufacturing of electrodes by conventional textile processes, like lamination or sewing, therefore facilitating the transition from lab prototyping to industrial manufacturing. Replacing the traditional silver thread as conductive element in the fabrication of Textrodes will definitely reduce the material cost per Textrode. Biocompatibility issues and manufacturability issues must be addressed but the exhibited functional performance is showing encouraging results.

The application of textile electrodes has been widely studied for biopotential recordings, especially for monitoring cardiac activity. Commercially available applications, such as the Adistar T-shirt and the Numetrex Cardioshirt, have shown good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for electrical bioimpedance (EBI) spectroscopy measurements in home and personalized health monitoring applications, however solid basic research about the measurement performance of the electrodes must be performed prior to the development of any textile-enabled EBI application. This research work studies the performance of EBI spectroscopy measurements when performed with textile electrodes. An analysis using an electrical circuit equivalent model and experimental data obtained with the Impedimed spectrometer SFB7 was carried out. The experimental study focused on EBI spectroscopy measurements obtained with different types of textile electrodes and in different measurement scenarios. The equivalent model analysis focused on the influence of the electrode polarization impedance Zep on the EBI spectroscopy measurements in the frequency range of 3 kHz to 500 kHz. The analysis of the obtained complex EBI spectra shows that the measurements obtained with textile electrodes produce constant and reliable EBI spectra. The results also indicate the importance of the skin-electrode interface in EBI spectroscopy measurement. Textile technology, if successfully integrated, may enable the performance of EBI spectroscopy measurements in new scenarios, which would allow the generation of novel, wearable, or textile-enabled applications for home and personal health monitoring

Electrical Bioimpedance Spectroscopy (EBIS) has been widely use for assessment of total body composition and fluid distribution. (EBIS) measurements are commonly performed with electrolytic electrodes placed on the wrist and the ankle with a rather small skin–electrode contact area. The use of textile garments for EBI requires the integration of textrodes with a larger contact area surrounding the limbs in order to compensate the absence of electrolytic medium commonly present in traditional Ag/AgCl gel electrodes. Recently it has been shown that mismatch between the measurements electrodes might cause alterations on the EBIS measurements. When performing EBIS measurements with textrodes certain differences have been observed, especially at high frequencies, respect the same EBIS measurements using Ag/AgCl electrodes. In this work the influence of increasing the skinelectrode area on the estimation of body composition parameters has been study performing experimental EBIS measurement. The results indicate that an increment on the area of the skin-electrode interface did produce noticeable changes in the bioimpedance spectra as well as in the body composition parameters. This influence must be taken into consideration when designing and testing textile-enable EBIS measurement systems.

Research efforts in the areas of Electrical Bioimpedance (EBI) and textile materials with conductive properties have contributed to the proliferation of research projects aiming to test the feasibility of implementing Textile-enabled instrumentation for performing EBI measurements. Most of the work done has been focused on the electrical characterization of the Textrodes (textile electrodes) and on spectroscopy applications of EBI like early detection of Cardiogenic Pulmonary Edema. In this work, a garment composed of two belts containing Textrodes made of conductive Velcro, loops-type, has been manufactured. Both, the abdomen and the neck belts, have four Textrodes connected through a conductive fabric Technik Tex P-130+ Shieldex fabric in pairs. This way, a tetrapolar EBI measurement between the neck and the chest is performed, implementing a typical band electrode arrangement [1] approach with the two belts. Using a custom-made device Respimon that measures the electrical cardiac activity with a 1-lead ECG and a tetrapolar EBI measurement at 50kHz of a portion of the body, and the Textrode garment, the ICG and ECG signals have been recorded and compared with the recordings obtained with Ag/AgCl electrodes placed in the same positions. The resemblance of the ICG and ECG signals obtained with both the Ag/AgCl electrodes and the Textrode garment confirms the feasibility of using Textrodes to perform measurements of cardiac impedance. There are several useful hemodynamic parameters that can be extracted from the ICG signal in combination with the ECG signal. The availability of a Textrode garment, easy to wear and that produces reliable ICG measurements, would contribute to present ICG monitoring as feasible technology for implementing personalized healthcare monitoring systems, especially for e-health applications of heart failure patients management.

Textile technology has gone through a remarkable development in the field of Smart Textiles and more specifically in the area of conductive fabrics and yarns. Important research efforts have been done worldwide and especially in Europe, where the EUcommission has supported several research projects in the near past e.g. BIOTEX IST-2004- 016789, CONTEXT IST- 2004-027291 and MyHeart IST-2002-507816. As a result of such worldwide R&D efforts, textile sensors and electrodes are currently available commercially. Nowadays there are even consumer products with textile sensing technology for heart rate monitoring integrated in the apparel e.g. Adistar Fusion T-shirt from Adidas or the Numetrex’s Cardio shirt. Since one of the main areas of focus where R&D efforts have been concentrated is Personalized Healthcare Monitoring (PHM) and the fact that most of the efforts developing textile sensors have been focused on developing electrodes for biopotential signals recording, it is natural that the main targeted application has been the acquisition of electrical biopotentials and especially monitoring the ElectroCardioGraphic activity, but also other types of textile sensors have been investigated e.g. textile stretching sensor (Mattmann et al., 2008). Nowadays textile-enable stretch sensors are available commercially like the one manufactured by Merlin Systems. While the application of this type of sensor aims at other applications than biopotential recordings, an important area of application of stretch sensors still is PHM and fitness. This type of sensors can be used for respiration monitoring or plethysmography applications.

Textile Electrodes have been widely studied for biopotentials recordings, specially for monitoring the cardiac activity. Commercially available applications, such as Adistar T-shirt and Textronics Cardioshirt, have proved a good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for Electrical Bioimpedance Spectroscopy measurements enabling home and personalized health monitoring applications however solid ground research about the measurement performance of the electrodes must be done prior to the development of any textile-enabled EBI application. In this work a comparison of the measurement performance of two different types of dry-textile electrodes and manufacturers has been performed against standardized RedDot 3M Ag/AgCl electrolytic electrodes. 4-Electrode, whole body, Ankle-to-Wrist EBI measurements have been taken with the Impedimed spectrometer SFB7 from healthy subjects in the frequency range of 3kHz to 500kHz. Measurements have been taken with dry electrodes at different times to study the influence of the interaction skin-electrode interface on the EBI measurements. The analysis of the obtained complex EBI spectra shows that the measurements performed with textile electrodes produce constant and reliable EBI spectra. Certain deviation can be observed at higher frequencies and the measurements obtained with Textronics and Ag/AgCl electrodes present a better resemblance. Textile technology, if successfully integrated it, may enable the performance of EBI measurements in new scenarios allowing the rising of novel wearable monitoring applications for home and personal care as well as car safety.

Electrodes have been widely studied for biopotentials recordings, specially for monitoring the cardiac activity. Commercially available applications, such as Adistar T-shirt and Textronics Cardioshirt, have proved a good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for Electrical Bioimpedance Spectroscopy measurements enabling home and personalized health monitoring applications however solid ground research about the measurement performance of the electrodes must be done prior to the development of any textile-enabled EBI application. In this work a comparison of the measurement performance of two different types of dry-textile electrodes and manufacturers has been performed against standardized RedDot 3M Ag/AgCl electrolytic electrodes. 4-Electrode, whole body, Ankle-to-Wrist EBI measurements have been taken with the Impedimed spectrometer SFB7 from healthy subjects in the frequency range of 3kHz to 500kHz. Measurements have been taken with dry electrodes at different times to study the influence of the interaction skin-electrode interface on the EBI measurements. The analysis of the obtained complex EBI spectra shows that the measurements performed with textile electrodes produce constant and reliable EBI spectra. Certain deviation can be observed at higher frequencies and the measurements obtained with Textronics and Ag/AgCl electrodes present a better resemblance. Textile technology, if successfully integrated it, may enable the performance of EBI measurements in new scenarios allowing the rising of novel wearable monitoring applications for home and personal care as well as car safety