User-interactive wirelessly-communicating “smart” textiles made from multimaterial fibers

En raison de la nature intime des interactions homme-textiles (essentiellement, nous sommes entourés par les textiles 24/7 - soit sous la forme de vêtements que nous portons ou comme rembourrage dans nos voitures, maisons, bureaux, etc.), les textiles intelligents sont devenus des plates-formes de plus en plus attrayantes pour les réseaux de capteurs innovants biomédicaux, transducteurs, et des microprocesseurs dédiés à la surveillance continue de la santé. En même temps, l'approche commune dans le domaine des textiles intelligents consiste en l'adaptation de la microélectronique planaire classique à une sorte de substrat souple. Cela se traduit souvent par de mauvaises propriétés mécaniques et donc des compromis au niveau du confort et de l'acceptation des usagers, qui à leur tour peuvent probablement expliquer pourquoi ces solutions émergent rarement du laboratoire et, à l'exception de certains cas très spécifiques, ne soit pas utilisés dans la vie de tous les jours. Par ailleurs, nous assistons présentement à un changement de paradigme au niveau de l'informatique autonome classique vers le concept de calculs distribués (ou informatique en nuage). Dans ce cas, la puissance de calcul du nœud individuel ou d'un dispositif de textile intelligent est moins importante que la capacité de transmettre des données à l'Internet. Dans ce travail, je propose une nouvelle approche basée sur l'intégration de polymère, verre et métal dans des structures de fibres miniaturisées afin de réaliser des dispositifs de textiles intelligents de prochaine génération avec des fonctionnalités de niveau supérieur (comme la communication sans fil, la reconnaissance tactile, les interconnexions électriques) tout en ayant une forme minimalement envahissante. Tout d'abord, j'étudie différents modèles d'antennes compatibles avec la géométrie des fibres et des techniques de fabrication. Ensuite, je démontre expérimentalement que ces antennes en fibres multi-matériaux peuvent être intégrées dans les textiles lors d’un processus standard de fabrication de textiles. Les tests effectués sur ces textiles ont montré que, pour les scénarios «sur-corps et hors-corps», les propriétés émissives en termes de perte de retour (S11), le patron (diagramme) de radiation, l'efficacité (gain), et le taux d'erreur binaire (TEB) sont directement comparables à des solutions classiques rigides. Ces antennes sont adéquates pour les communications à courte portée des applications de communications sans fil ayant un débit de données de Mo/s (méga-octets par seconde) (via protocoles Bluetooth et IEEE 802.15.4 à la fréquence de 2,4 GHz). Des simulations numériques de taux d'absorption spécifique démontrent également le plein respect des règles de sécurité imposées par Industrie Canada pour les réseaux sans fil à proximité du corps humain. Puisque les matériaux composites de fibres métal-verre-polymère sont fabriqués en utilisant des fibres de silice creuses de diamètre submillimétrique et la technique de dépôt d'argent à l'état liquide, les éléments conducteurs sont protégés de l'environnement et ceci préserve aussi les propriétés mécaniques et esthétiques des vêtements. Cet aspect est confirmé par des essais correspondant aux normes de l'industrie du textile, l'étirement standard et des essais de flexion. De plus, appliquer des revêtements superhydrophobes (WCA = 152º, SA = 6º) permet une communication sans fil sans interruption de ces textiles sous l'application directe de l'eau, même après plusieurs cycles de lavage. Enfin, le prototype de textile intelligent fabriqué interagit avec l'utilisateur à travers un détecteur tactile et transmet les données tactiles à travers le protocole Bluetooth à un smartphone. Cette démonstration valide l’approche des fibres multi-matériaux pour une variété d'applications.As we are surrounded by textiles 24/7, either in the form of garments that we wear or as upholstery in our cars, homes, offices, etc., textiles are especially attractive platforms for arrays of innovative biomedical sensors, transducers, and microprocessors dedicated, among other applications, to continuous health monitoring. In the same time, the common approach in the field of smart textiles consists in adaptation of conventional planar microelectronics to some kind of flexible substrate, which often results in poor mechanical properties and thus compromises wearing comfort and complicates garment care, which results in low user acceptance. This explains why such solutions rarely emerge from the lab and, with the exception of some very specific cases, cannot be seen in the everyday life. Furthermore, we are currently witnessing a global shift from classical standalone computing to the concept of distributed computation (e.g. so-called thin clients and cloud storage). In this context, the computation power of the individual node or smart textile device in this case, becomes progressively less important than the ability to relay data to the Internet. In this work, I propose a novel approach based on the idea of integration of polymer, glass and metal into miniaturized fiber structures in order to achieve next-generation smart textile devices with higher-level functionalities, such as wireless communication, touch recognition, electrical interconnects, with minimally-invasive attributes. First, I investigate different possible fiber-shaped antenna designs and fabrication techniques. Next, I experimentally demonstrate that such multi-material fiber antennas can be integrated into textiles during standard textile manufacturing process. Tests conducted on these textiles have shown that, for on-body and off-body scenarios, the emissive properties in terms of return loss (S11), radiation pattern, efficiency (gain), and bit-error rate (BER) are directly comparable to classic ‘rigid’ solutions and adequately address short-range wireless communications applications at Mbps data-rates (via Bluetooth and IEEE 802.15.4 protocols at 2.4 GHz frequency). Numerical simulations of the specific absorption rate (SAR) also demonstrate full compliance with safety regulations imposed by Industry Canada for wireless body area network devices. Since metal-glass-polymer fiber composites were fabricated using sub-millimetre hollow-core silica fibers and liquid state silver deposition technique, the conductor elements are shielded against the environment and preserve the mechanical and cosmetic properties of the garments. This is confirmed by the textile industry standard stretching and bending tests. Additionally, applied superhydrophobic coatings (WCA=152º, SA=6º) allow uninterrupted wireless communication of the textiles under direct water application even after multiple washing cycles. Finally, I fabricated a user-interactive and wireless-communicating smart textile prototype, that interacts with the user through capacitive touch-sensing and relays the touch data through Bluetooth protocol to a smartphone. This demonstration validates that the proposed approach based on multi-material fibers is suitable for applications to sensor fabrics and bio-sensing textiles connected in real time to mobile communications infrastructures, suitable for a variety of health and life science applications

Wearable contactless respiration sensor based on multi-material fibers integrated into textile

In this paper, we report on a novel sensor for the contactless monitoring of the respiration rate, made from multi-material fibers arranged in the form of spiral antenna (2.45 GHz central frequency). High flexibility of the used composite metal-glass-polymer fibers permits their integration into a cotton t-shirt without compromising comfort or restricting movement of the user. At the same time, change of the antenna geometry, due to the chest expansion and the displacement of the air volume in the lungs, is found to cause a significant shift of the antenna operational frequency, thus allowing respiration detection. In contrast with many current solutions, respiration is detected without attachment of the electrodes of any kind to the user’s body, neither direct contact of the fiber with the skin is required. Respiration patterns for two male volunteers were recorded with the help of a sensor prototype integrated into standard cotton t-shirt in sitting, standing, and lying scenarios. The typical measured frequency shift for the deep and shallow breathing was found to be in the range 120–200 MHz and 10–15 MHz, respectively. The same spiral fiber antenna is also shown to be suitable for short-range wireless communication, thus allowing respiration data transmission, for example, via the Bluetooth protocol, to mobile handheld devices

Theoretical investigation and numerical simulations of RF textiles antennas performance

Ce travail est consacré à la théorie et aux simulations numériques des nouveaux textiles qui peuvent communiqués sans-fil et composé des antennes fibre multimatériaux. La recherche est conduite par une tentative à changer le concept de "wearables" de grands dispositifs montés sur le corps à des dispositifs cachés confortables intégrés dans vos vêtements. Les textiles RF peuvent être prévus dans divers secteur des soins de santé, pour la surveillance des enfants et des personnes âgées, dans les domaines de télémédecine, de sécurité et de la recherche et sauvetage. Les antennes RF textiles, précédemment développées dans notre groupe, sont constituées de fibre multimatériaux en incorporant une couche conductrice d'argent dans un capillaire silice de 100 µm de diamètre à l'aide de la technique de déposition de phase liquide. La structure de ces antennes portables est flexible, se conforme au corps et non invasif. Dans ce travail, la performance de deux antennes de fibre, l'antenne dipôle et boucle, sont examinés à la bande de fréquence ISM par des simulations numériques à l'aide de logiciel ANSYS HFSS dans l'espace libre et sur le corps. À cette fin, le modèle de corps humain à plusieurs couches spécifiques a été développé en s'inspirant des valeurs proposées par le FCC "Federal Communications Commission" pour assigner les propriétés diélectriques de chaque tissu et pour satisfaire toutes les mesures de sécurité. Les résultats stimulés comprennent le déplacement de fréquence de résonance, les diagrammes de rayonnement affectés, le champ de rayonnement au-dessus du corps, l'efficacité et les mesures de SAR. En outre, la séparation de corps de l'antenne et les effets météorologiques sont également examinés. Les résultats présentés sont ensuite analysés en ce qui concerne les avantages et les inconvénients des deux designs, particulièrement dans le scénario sur le corps, tel qu'une attention spéciale est accordée à la robustesse et l'immunité contre la proximité du corps humain.This work is devoted to the theory and numerical simulations of novel wireless-communicating textiles featuring multi-material RF fiber antennas embedded into textiles. The research is driven by an attempt to change the concept of wearables from large devices mounted on the body to a hidden and comfortable wearables integrated into your clothes. RF textiles antennas are expected to find multiple applications in various sectors of healthcare, child and elderly monitoring - telemedicine and home-nursing, security, search and rescue. RF textiles antennas, previously developed in our group, are made from multi-material fiber by incorporating a conductive layer of silver within a silica capillary of 100μm diameter using liquid phase deposition technique. The structure of these wearable antennas is flexible, conform to the body, and non-invasive. In this work the performance of two fiber antennas, namely dipole and loop, is investigated at ISM-band through numerical simulations using ANSYS HFSS both in free space and on-body scenario. For this purpose, the specific multi-layer human body model was developed using the “Federal Communication Commission” guidelines to assign the dielectric properties of each tissue and to satisfy all safety regulations. Simulated results include the shifting of resonance frequency, affected radiation patterns, radiation field above the body, efficiency and SAR measurements. In addition, antenna-body-separation distance and weather effects are also investigated. Presented results are then analyzed in terms of pros and cons of the two fiber antenna designs, especially in on-body scenario, as special attention is given to the robustness and immunity against the vicinity of human body

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

Emerging and Disruptive Next-Generation Technologies for POC: Sensors, Chemistry and Microfluidics for Diagnostics

Recently, the attention paid to self-care tests and the easy and large screening of a high number of people has dramatically increased. Indeed, easy and affordable tools for the safe management of biological fluids together with self-diagnosis have emerged as compulsory requirements in this time of the COVID-19 pandemic, to lighten the pressure on public healthcare institutions and thus limiting the diffusion of infections. Obviously, other kinds of pathologies (cancer or other degenerative diseases) also continue to require attention, with progressively earlier and more widespread diagnoses. The contribution to the development of this research field comes from the areas of innovative plastic and 3D microfluidics, smart chemistry and the integration of miniaturized sensors, going in the direction of improving the performances of in vitro diagnostic (IVD) devices. In our Special Issue, we include papers describing easy strategies to identify diseases at the point-of-care and near-the-bed levels, but also dealing with innovative biomarkers, sample treatments, and chemistry processes which, in perspective, represent promising tools to be applied in the field

The 2021 flexible and printed electronics roadmap

This roadmap includes the perspectives and visions of leading researchers in the key areas of flexible and printable electronics. The covered topics are broadly organized by the device technologies (sections 1–9), fabrication techniques (sections 10–12), and design and modeling approaches (sections 13 and 14) essential to the future development of new applications leveraging flexible electronics (FE). The interdisciplinary nature of this field involves everything from fundamental scientific discoveries to engineering challenges; from design and synthesis of new materials via novel device design to modelling and digital manufacturing of integrated systems. As such, this roadmap aims to serve as a resource on the current status and future challenges in the areas covered by the roadmap and to highlight the breadth and wide-ranging opportunities made available by FE technologies

LOW-RESOLUTION CUSTOMIZABLE UBIQUITOUS DISPLAYS

In a conventional display, pixels are constrained within the rectangular or circular boundaries of the device. This thesis explores moving pixels from a screen into the surrounding environment to form ubiquitous displays. The surrounding environment can include a human, walls, ceiling, and floor. To achieve this goal, we explore the idea of customizable displays: displays that can be customized in terms of shapes, sizes, resolutions, and locations to fit into the existing infrastructure. These displays require pixels that can easily combine to create different display layouts and provide installation flexibility. To build highly customizable displays, we need to design pixels with a higher level of independence in its operation. This thesis shows different display designs that use pixels with pixel independence ranging from low to high. Firstly, we explore integrating pixels into clothing using battery-powered tethered LEDs to shine information through pockets. Secondly, to enable integrating pixels into the architectural surroundings, we explore using battery-powered untethered pixels that allow building displays of different shapes and sizes on a desired surface. The display can show images and animations on the custom display configuration. Thirdly, we explore the design of a solar-powered independent pixel that can integrate into walls or construction materials to form a display. These pixels overcome the need to recharge them explicitly. Lastly, we explore the design of a mechanical pixel element that can be embedded into construction material to form display panels. The information on these displays is updated manually when a user brushes over the pixels. Our work takes a step forward in designing pixels with higher operation independence to envision a future of displays anywhere and everywhere

Smart Textiles for Tactile Sensing and Energy Storage

Durant ma maîtrise, j’ai surtout travaillé sur 2 sujets dans le domaine des textiles intelligents électroactifs. Mon premier projet portait sur la fabrication d’un pad textile sensible au toucher utilisant des fibres capacitives en polymères. Les fibres capacitives, présentent une grande capacité et résistance, ont été fabriquées utilisant des techniques de fibrage. Pour permettre une connectivité facile, un mince fil de cuivre a été intégré dans le coeur de la fibre durant l’extrusion. Ces fibres (soft-capacitor) ont des une capacité par unité de longueur typiques de 69 nF/m, et des résistances de 5 kΩ•m. Nos mesures et nos modèles théoriques montrent que la capacité est un paramètre très stable déterminé par la géométrie utilisée, qui ne dépend pas du diamètre de la fibre ni de ses paramètres de fabriquation. La resistivité de la fibre, quant à elle, a un important coefficient thermique (positif), est très sensible aux contraintes de tension et dépend grandement des paramètre d’extrusion. Il a aussi été démontré qu’une fibre capacitive individuelle peut servir de capteur de glissement qui permet de déterminer, sur sa longueur, la position du contact tactile en mesurant la réponse AC de la fibre à un point donné sur sa surface. La réponse électrique d’un senseur de ce type est décrite par le modèle de réseau RC, qui est en accord avec les résultats expérimentaux. Les fibres capacitives développées sont souples, de faible diamètre, légères et n’utilisent pas d’électrolyte liquide, donc elles sont idéales pour l’intégration dans les produits textiles. À la fin du chapitre, nous avons démontré qu’en tissant un ensemble de fibres capacitives en 1 dimension (fibres parallèles), il est possible de tisser un senseur tactile en 2 dimensions. Les performances de ce senseur ont été caractérisées et une bonne isolation entre les canaux a été démontrée. Un tel senseur possède aussi des fonctionnalités multi-touch. Mon deuxième projet portait sur l’assemblage de cellules Li-ion flexibles et étirables, leur intégration dans un textile et leur caractérisation électrique dans un contexte de «textiles intelligents». L’aspect chimique de ces cellules a été développé par mon collègue Y.Liu, qui a réussi à intégrer la cathode (LiFePO4), l’anode (Li4Ti5o12) et l’électrolyte solide (PEO) dans un système de cellule électrochimique souple. J’ai démontré de façon expérimentale que des batteries de cellules flexibles peuvent être fabriqués en grande feuilles, puis coupées en fines ---------- Abstract During my master’s I have mainly worked on two subjects in the research area of electroactive smart textiles. My first project involved building a touch sensitive textile pad using original home-made allpolymer soft capacitor fibers. The capacitor fibers featuring relatively high capacitance and resistance were fabricated using fiber drawing technique. For the ease of connectorization, a thin copper wire was integrated into the fiber core during drawing procedure. Soft-capacitor fibers have a typical capacitance per unit length of 69 nF/m, and a typical resistivity parameter of 5 kΩ•m. Our measurements and theoretical modeling show that the fiber capacitance is a very stable, geometry defined parameter independent of the fiber diameter, and fiber fabrication parameters. In contrast, fiber resistivity has a very strong positive temperature coefficient, it is highly sensitive to stretching, and it is strongly dependent on the fiber drawing parameters. Next, an individual capacitor fiber was demonstrated to act as a slide sensor that allows determining the touch position along its length by measuring the fiber AC response at a single point at the fiber surface. Electrical response of such a sensor was described by the RC ladder model, with the modelling data in excellent agreement with experimental observations. Developed capacitor fibers are soft, small diameter, lightweight and do not use liquid electrolytes, thus they are ideally suited for the integration into textile products. At the end of the chapter, we have demonstrated that by weaving a one dimensional array of capacitor fibers (in parallel to each other) a fully woven 2D touchpad sensor could be build. Performance of a touchpad sensor was then characterised and the absence of the inter-channel crosstalk was confirmed. We also note that a 2D touchpad has a partial multi-touch functionality. My second project involved assembly of flexible and stretchable Li-ion batteries, their integration into a textile, and their electric characterization in a view of smart textile applications. The chemistry for the battery was developed by my colleague Y. Liu who has combined the relatively conventional Li battery materials including LiFePO4 cathode, Li4Ti5O12 anode and PEO solid electrolyte into a non-conventional soft electrochemical battery system. I have experimentally demonstrated that flexible batteries can be first cast as sheets, and then cut into thin strips, and finally integrated into textile using conventional weaving techniques. Th

Graphene-based wearable temperature sensors: A review

The paper presents a comprehensive review of the use of graphene to develop wearable temperature sensors. The detection of temperature over a wide range has been a growing interest in multidisciplinary sectors in the sensing world. Different kinds of flexible temperature sensors have been fabricated with a range of polymers and nanomaterials. With the additional attribute of wearable nature, these temperature sensors are used ubiquitously to determine the effect of physiochemical variations happening in the environment of the chosen biomedical and industrial applications. Graphene, owing to its exceptional electrical, mechanical, and thermal properties, has been extensively used for the development of wearable temperature sensors. The prototypes have been deployed with certain wireless communication protocols to transfer the experimental data obtained under both controlled environments and real-time scenarios. This paper underlines some of the significant works done on the use of graphene to fabricate and implement wearable temperature sensors, along with the possible remedial steps that can be considered to deal with the challenges existing in the current literature

Smart Textiles Production

The research field of smart textiles is currently witnessing a rapidly growing number of applications integrating intelligent functions in textile substrates. With an increasing amount of new developed product prototypes, the number of materials used and that of specially designed production technologies are also growing. This book is intended to provide an overview of materials, production technologies, and product concepts to different groups concerned with smart textiles. It will help designers to understand the possibilities of smart textile production, so that they are enabled to design this type of products. It will also help textile and electronics manufacturers to understand which production technologies are suitable to meet certain product requirements