The application of textile electrodes has been widely studied for biopotential recordings,especially for monitoring cardiac activity. Commercially available applications, such as theAdistar T-shirt and the Numetrex Cardioshirt, have shown good performance for heart ratemonitoring and are available worldwide.Textile technology can also be used for electrical bioimpedance (EBI) spectroscopymeasurements in home and personalized health monitoring applications, however solid basicresearch about the measurement performance of the electrodes must be performed prior to thedevelopment of any textile-enabled EBI application.This research work studies the performance of EBI spectroscopy measurements whenperformed with textile electrodes. An analysis using an electrical circuit equivalent model andexperimental data obtained with the Impedimed spectrometer SFB7 was carried out. Theexperimental study focused on EBI spectroscopy measurements obtained with different types oftextile electrodes and in different measurement scenarios. The equivalent model analysis focusedon the influence of the electrode polarization impedance Zep on the EBI spectroscopymeasurements in the frequency range of 3 kHz to 500 kHz.The analysis of the obtained complex EBI spectra shows that the measurements obtainedwith textile electrodes produce constant and reliable EBI spectra. The results also indicate theimportance of the skin-electrode interface in EBI spectroscopy measurement.Textile technology, if successfully integrated, may enable the performance of EBIspectroscopy measurements in new scenarios, which would allow the generation of novel,wearable, or textile-enabled applications for home and personal health monitoring / <p>Thesis Supervisors: Kaj Lindecrantz and Fernando Seoane</p><p><b>Sponsorship</b>:</p><p>Mexican CONACYT</p>

Functional garments for physiological sensing purposes have been utilized in several disciplinesi.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 physiologicalmeasurements. Electrical Bioimpedance (EBI) is a non-invasive and effective technology that canbe used for detection and supervision of different health conditions. In some specific applicationssuch as body composition assessment EBIS has shown encouraging results proving good degreeof effectiveness and reliability. In a similar way Impedance Cardiography (ICG) is anothermodality of EBI primarily concerned with the determination of Stroke Volume SV, indices ofcontractility, and other aspects of hemodynamics.EBI technology in the previously mentioned modalities can benefit from a integration with agarment; however, a successful implementation of EBI technology depends on the goodperformance of textile electrodes. The main weakness of Textrodes is a deficient skin-electrodeinterface which produces a high degree of sensitivity to signal disturbances. This sensitivity canbe reduced with a suitable selection of the electrode material and an intelligent and ergonomicgarment design that ensures an effective skin-electrode contact area.This research work studies the performance of textile electrodes and garments for EBIspectroscopy for Total Body Assessment and Transthoracic Electrical Bioimpedance (TEB) forcardio monitoring. Their performance is analyzed based on impedance spectra, estimation ofparameters, influence of electrode polarization impedance Zep and quality of the signals using asreference Ag/AgCl electrodes. The study includes the analysis of some characteristics of thetextile electrodes such as conductive material, skin-electrode contact area size and fabricconstruction.The results obtained in this research work present evidence that textile garments with a dry skinelectrodeinterface like the ones used in research produce reliable EBI measurements in bothmodalities: BIS for Total Body Assessment and TEB for Impedance Cardiography. Textiletechnology, if successfully integrated, may enable the utilization of EBI in both modalities andconsequently implementing wearable applications for home and personal health monitoring. / <p>QC 20121213</p>

The development in textile technology has led to electrodes and wearable measuringsystems. For the implementation of wearable systems is necessary to characterize properly theelectrodes and its influence in generating measurements. The validation of the performance oftextiles electrodes must be made with real ECG measurements.To obtain this ECG with textiles electrodes, a system must be implemented. This systemshould integrate an ECG amplifier, an USB DAQ system, the obtained data is received by aLabview application which stored this data in an ASCII text file. This text file is used tosubsequent study in a power analytical application, for example, Matlab.

The medical field has been a part of the smart textile area for quite some time. With time come technological advancement and the two fields converge on more and more areas. One such area is that of using textile electrodes, textrodes, for measuring bioelectrical activity, such as heart rate for ECG analysis. There are many components that make for a successful textile electrode and though many studies have been made in the subject there are several aspects that still are difficult. By using textile electrodes the problem with skin irritation from electrolyte gels, commonly used for conventional electrodes, is avoided, however dry textrodes create disturbances in the output signal (heart rate) while subjected to movement and internal dimensional changes. The addition of moisture to a textrode has shown to decrease these intermittent disturbances but the knowledge about fundamental textile structural influence in the matter has not been fully investigated. This study investigates a flat, a 2-thread fleece and an open structure, and their relation to moisture both as textile structures and as textrodes. This way the possibilities of utilising moisture to increase performance in a textrode purpose can be examined and to what extent the textile structure plays a part in that exploitation. The material composition of textile structures also affects their properties The introduction of assistive materials, polyester and viscose, into the Shieldex (conductive yarn) structures is done to test core moisture management properties such as surface tension, absorption and moisture content, and correlate them to electrical properties necessary for textrode function. In the end the gap between textile structure and end product in form of a textrode is closed as the impedance and microclimate of the textrodes are studied. This is mainly to tie together the fundamental textile structures with a complex textile construction. In conclusion the complexity is also confirmed as structural, materialistic and external influences has an impact on the results. The influence of moisture on lowered resistance and impedance in the structures is confirmed but the impact of textile structure can also be seen. The 2-thread fleece and open structures often has a more positive impact on results and therefore has the possibility of enhancing performance of a textrode for bioelectrical signal monitoring. With these results a more effective way of producing long-lasting, patient-friendly, textrodes can be derived and in the future lead to better care in the medical areas.

Neuromuscular electrical stimulation (NMES) is a modality of electrotherapy which is aiming to restore and improve muscle function by injecting small levels of current into the muscle using different types of electrodes. Advantages are seen in using textile electrodes which can be integrated into wearables. Previous research has been done for the development of textile stimulation electrodes. However, the focus has not been on the electrode construction itself. Therefore, the influence of electrode construction parameters of knitted electrodes as well as of the electrode condition, i.e. wet or dry, on the skin-electrode impedance and on the perceived stimulation comfort were analysed. Further, the application of pressure to the electrode was investigated. It was found that the electrode condition is the most important parameter for the electrode performance as a wet electrode showed a lower impedance and an improved stimulation comfort with a better skin contact. Followed by this, the pressure was the second most important factor, especially for dry electrodes. A higher pressure reduced the skin-electrode impedance and improved the skin contact in dry condition. Nevertheless, dry electrodes with a high applied pressure still performed worse than wet electrodes. Regarding the electrode design, the most important factor was the electrode size. A bigger size reduced the impedance. Nevertheless, for the application in NMES, a smaller electrode size is to be preferred as it improved the stimulation selectivity and thus, a lower NMES level was required to induce a plantarflexion without affecting the stimulation comfort. The other investigated construction parameters (binding, yarn density, shape) only showed minor influences on the electrode performance. Therefore, the possibilities of applying pressure to the electrode to improve the performance of dry textile electrodes should be further investigated.