“Smart textile” as a notion was demarcated approximately 25 years ago, leading to an enthusiastic hype around the research. Both academic efforts and members of the maker community developed prototypes and artistic creations that incorporated smart features into textiles. From the start of this research era, numerous authors suggested that smart textiles had the potential to revolutionise the healthcare sector. At around the same time, the European Commission had started raising concerns about the demographic trends in Europe, with an ageing population and decreasing birth rates. The need for long-term solutions to address the predicted increase in healthcare demands became evident. Despite 25 years of research with many papers suggesting a soon-to-come commercial breakthrough for smart textiles, such a breakthrough has yet to be seen. There is only a handful of smart textile products on the market currently, and the much-anticipated improvement in the healthcare sector promised by smart textile research is still absent. At the time of writing this thesis, the European Standardisation Committee (CEN) expresses the view that part of the reason for the lack of a commercial breakthrough for smart textiles is the absence of regulations and standards. Technical reports and testing standards regarding smart textiles are being issued continuously by both the International Electrotechnical Committee (IEC), the CEN and the International Organization for Standardization (ISO). These organisations also strive to harmonise the issued guidelines. It is crucial that these regulatory documents describe metrics that are relevant to the applications. Moreover, if easily adopted textile-friendly methods for producing smart textile elements were available to potential producers, in addition to these regulations, the preconditions for a less financially risky market with better functioning smart textile products could be established. This, in turn, might stimulate an increase in the production of smart textile products intended for personalised health. This thesis summarises several aspects of smart textile intended for personalised health (P-health). It provides both suggestions on how to test elements of the textiles properly (their interface with the human body) and how to manufacture components of a smart textile system, such as electrodes and electrical routing. The main objectives of the work behind this thesis include: 1) investigating how functional building blocks for smart textile garments intended for p-health can be manufactured in a textile-friendly way and 2) investigating how to characterise these building blocks in the most appropriate way. It is concluded that such building blocks can be produced and used for smart textile garments in both daily life activities and therapeutic situations. The thesis demonstrates the production of electrically insulated routing integrated into a textile fabric, all done in a single textile production step. For the measurement methods, it is argued that skin-electrode impedance between human subjects and textile electrodes should be measured in-vivo using a three-electrode setup. Additionally, the thesis proposes that instead of measuring sheet resistance, it is better to measure the resistance of the specific smart textile element, as it is shown that sheet resistance is not always applicable to conductive fabrics made from interlaced conductive yarns.

Development in the field of smart wearable products for monitoring daily life health status is beginning to spread in society. Textile electronic methods are improving and facilitating the manufacturing of sensorized garments. This paper evaluates a newly developed t-shirt incorporating electronic sensing and interconnecting elements integrated into the T-shirt with textile-friendly techniques sensorized with a Movesense device for monitoring ECG and HR and activity. The measurement results obtained from the t-shirt are entirely in agreement with the measurements obtained with other textile garments and encourage us for a near future where wearable sensors are just textile garments sensorized seamlessly without suboptimal textile-electronic integrated elements. 

Electro-stimulation to alleviate spasticity, pain and to increase mobility has been used successfully for years. Usually, gelled electrodes are used for this. In a garment intended for repeated use such electrodes must be replaced. The Mollii-suit by the company Inerventions utilises dry conductive rubber electrodes. The electrodes work satisfactory, but the garment is cumbersome to fit on the body. In this paper we show that knitted dry electrodes can be used instead. The knitted electrodes present a lower friction against the skin and a garment is easily fitted to the body. The fabric is stretchable and provides a tight fit to the body ensuring electrical contact. We present three candidate textrodes and show how we choose the one with most favourable features for producing the garment. We validate the performance of the garment by measuring three electrical parameters: rise time (10–90%) of the applied voltage, net injected charge and the low frequency value of the skin–electrode impedance. It is concluded that the use of flat knitting intarsia technique can produce a garment with seamlessly integrated conductive leads and electrodes and that this garment delivers energy to the body as targeted and is beneficial from manufacturing and comfort perspectives.

The development of smart wearable solutions for monitoring daily life health status is increasingly popular, with chest straps and wristbands being predominant. This study introduces a novel sensorized T-shirt design with textile electrodes connected via a knitting technique to a Movesense device. We aimed to investigate the impact of stationary and movement actions on electrocardiography (ECG) and heart rate (HR) measurements using our sensorized T-shirt. Various activities of daily living (ADLs), including sitting, standing, walking, and mopping, were evaluated by comparing our T-shirt with a commercial chest strap. Our findings demonstrate measurement equivalence across ADLs, regardless of the sensing approach. By comparing ECG and HR measurements, we gained valuable insights into the influence of physical activity on sensorized T-shirt development for monitoring. Notably, the ECG signals exhibited remarkable similarity between our sensorized T-shirt and the chest strap, with closely aligned HR distributions during both stationary and movement actions. The average mean absolute percentage error was below 3%, affirming the agreement between the two solutions. These findings underscore the robustness and accuracy of our sensorized T-shirt in monitoring ECG and HR during diverse ADLs, emphasizing the significance of considering physical activity in cardiovascular monitoring research and the development of personal health applications. 

The rise of interest in wearable sensing of bioelectrical signals conducted via smart textile systems over the past decades has resulted in many investigations on how to develop and evaluate such systems. All measurements of bioelectrical signals are done by way of electrodes. The most critical parameter for an electrode is the skin-electrode impedance. A common method for measuring skin-electrode impedance is the two-lead method, but it has limitations because it relies on assumptions of symmetries of the body impedance in different parts of the body as well as of the skin-electrode impedances. To address this, in this paper we present an easy-to-use and reliable three-lead in vivo method as a more accurate alternative. We aim to show that the in vivo three-lead method overcomes all such limitations. We aim at raising the awareness regarding the possibility to characterize textile electrodes using a correct, accurate and robust method rather than limited and sometimes inadequate and uninformative methods. The three-lead in vivo method eliminates the effect of body impedance as well as all other contact impedances during measurements. The method is direct and measures only the skin-electrode impedance. This method is suitable for characterization of skin-electrode interface of textile electrodes intended for both bioelectrical signals as well as for electrostimulation of the human body. We foresee that the utilization of the three-lead in vivo method has the potential to impact the further development of wearable sensing by enabling more accurate and reliable measurement of bioelectrical signals. 

Smart textiles offer ways to integrate sensing and actuating abilities into textile structures found in garments, furniture and other applications such as filters, reinforcements, disposable products and others. A large part of the research being done on smart textiles concerns the possibilities for monitoring human health and wellbeing. In recent years, the research community has shown an increasing interest in measuring pressure using smart textiles. Observations in previous work on electrically conductive fabrics had shown that the conductivity in these fabrics was not always isotropic and the assumption was that the contact resistance between the conductive elements (often yarns) was the source of this anisotropy. The work done in connection to this thesis investigates two questions regarding smart textiles: first electrical interconnections and second electrical sensing. An algorithm and a device for measuring the contact resistance in woven samples were developed. Results from that work showed that the contact resistance of woven samples can be measured and that in the case of metallized yarns the contact resistance does not pose a problem for interconnection. For the sensing part two explanatory models for the capacitance of a functionalized spacer-fabric under compression were developed and tested on measured data. The results indicate that both models provide reasonable agreement with the data up to ca 50% compression.

Abstract. The integration of performances in interactive textile fabric system has so far been rather complicated since they are based on multilayer or three-dimensional principles. These structures are today mainly put together by means of several processes, which is laborious and time consuming. In this interdisciplinary study we have combined the principle of a three-dimensional multilayer weaving process and interactive textiles structures in order to enable the manufacturing of interactive textile structure in one process. The process is investigated using a manual reconstructed loom and the approach has been to use the 3D structures in order to integrate and organize conductive and compressive spacer layers as a textile capacitive structure. Measurements on such a structure was done by construction a first order passive high pass filter and using the fabric sample as the capacitor and a 1MΩ resistor. The behavior of the measurement of the capacitive sensor is quite close to the theoretical calculation and already at this stage the structure might be used to indicate the presence of a pressure. In this project we have shown that a three-dimensional structure enables the development of interactive textiles in one process. Further the concept of using a rebuilt manual loom has shown great potential in early research stages. It is considerable saving time and resources since, in this case, it is easy to reconstruct the loom design compared to performing similar reconstruction on a machine. Future research will focus on developing other types of interactive structures. Another issue will be to scale down the size of the structures in order to get thinner and more flexible qualities.