E-Textiles. Study of the interaction between devices, connection methods and substrates

It is common knowledge that textiles and textile products are available in different forms along the textile chain. However, right now, all the attention is paid to the relationship between these materials and the most recent developments in the world of electronics. When a garment is implementing electronic components, ranging from sensors to conductor paths, that are applied or integrated into the textile surface, it’s commonly called an E-Textile. Nowadays there is a continuous demand for these products because they can satisfy a great extent of needs without interfering too much with the user’s life or without the obligation of modifying too much the original product in the beginning. This study, however, focuses on analyzing the interaction and interactivity which allows electronic communication between the components present in the textiles. It is believed that there is a knowledge gap in these most recent developments. In this paper, a literature investigation is carried out using various databases, which resulted in different contributions to the researched subjects. Also, an overview of materials, production technologies and testing methods is given. The concepts of smart and e-textile, textile structure, conductive materials, electronic communication and connection are classified. The influencing factors on the properties of the material structure are presented and a discussion is made referring to the potentials and challenges related to e-textiles. Finally, a brief consideration of sustainability and environmental aspects is done and, in the end, the main conclusions of the investigation are stated. The main focus of the research lies in defining processes and material properties for improving connection techniques between the textiles and the electronic components, and also between the components themselves. Only limited research will be conducted on simulating the behavior of these technologies. Various ideas for applications exist, starting from ones of classical nature (flexural rigid materials), to 3d printed additive manufacturing or other ones of a textile nature in the form of embroidered conductor paths. Unluckily little research has been conducted on real applications. Therefore, the challenges are only identified, and future research directions are derive

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

Shape Memory Polyurethane-Based Smart Polymer Substrates for Physiologically Responsive, Dynamic Pressure (Re)Distribution.

Shape memory polymers (SMPs) are an exciting class of stimuli-responsive smart materials that demonstrate reactive and reversible changes in mechanical property, usually by switching between different states due to external stimuli. We report on the development of a polyurethane-based SMP foam for effective pressure redistribution that demonstrates controllable changes in dynamic pressure redistribution capability at a low transition temperature (∼24 °C)-ideally suited to matching modulations in body contact pressure for dynamic pressure relief (e.g., for alleviation or pressure ulcer effects). The resultant SMP material has been extensively characterized by a series of tests including stress-strain testing, compression testing, dynamic mechanical analysis, optical microscopy, UV-visible absorbance spectroscopy, variable-temperature areal pressure distribution, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, differential scanning calorimetry, dynamic thermogravimetric analysis, and 1H nuclear magnetic resonance spectroscopy. The foam system exhibits high responsivity when tested for plantar pressure modulation with significant potential in pressure ulcers treatment. Efficient pressure redistribution (∼80% reduction in interface pressure), high stress response (∼30% applied stress is stored in fixity and released on recovery), and excellent deformation recovery (∼100%) are demonstrated in addition to significant cycling ability without performance loss. By providing highly effective pressure redistribution and modulation when in contact with the body's surface, this SMP foam offers novel mechanisms for alleviating the risk of pressure ulcers

Pinning-induced folding-unfolding asymmetry in adhesive creases

The compression of soft elastic matter and biological tissue can lead to creasing, an instability where a surface folds sharply into periodic self-contacts. Intriguingly, the unfolding of the surface upon releasing the strain is usually not perfect: small scars remain that serve as nuclei for creases during repeated compressions. Here we present creasing experiments with sticky polymer surfaces, using confocal microscopy, which resolve the contact line region where folding and unfolding occurs. It is found that surface tension induces a second fold, at the edge of the self-contact, which leads to a singular elastic stress and self-similar crease morphologies. However, these profiles exhibit an intrinsic folding-unfolding asymmetry that is caused by contact line pinning, in a way that resembles wetting of liquids on imperfect solids. Contact line pinning is therefore a key element of creasing: it inhibits complete unfolding and gives soft surfaces a folding memory.Comment: 8 pages, 6 figure

Analysis of failure mechanisms of machine embroidered electrical contacts and solutions for improved reliability

In recent years, a number of research projects and patents have proposed to apply embroidery of conductive yarn to build electric circuits on textile substrates. To contact electronic modules or components to these circuits, embroidery itself was applied as a contacting method. Thereby, the embroidery needle is stitching through a conductive pad on an electronic substrate and is laying the conductive thread over this pad. The yarn and the pad establish an electrical contact. However, until today this contacting technology based on embroidery has not been adopted by the industry since reliability issues during stress were reported by different researchers. Yet, neither these failure phenomena were investigated comprehensively, nor was it attempted to understand their cause. This inhibited potential improvements to make these embroidered contacts reliable. Furthermore, the lack of alternative technologies for a reliable and volume producible contacting of embroidered circuits with electronic components or modules kept embroidered circuits from evolving to actual products. Therefore, this thesis primarily develops an understanding of the contact mechanism underlying embroidered contacts, and develops a theory that explains the failure phenomena. Secondarily the thesis overcomes these reliability issues by improving these contacts and by finding alternatives. The ultimate goal beyond this thesis is a volume producible contacting process. Therefore, this thesis looks mainly at machine embroidered contacts

Superphobicity/philicity janus fabrics with Switchable, spontaneous, directional transport ability to water and oil fluids

Herein we demonstrate that switchable, spontaneous, directional-transport ability to both water and oil fluids can be created on fabric materials through wet-chemistry coating and successive UV irradiation treatment. When the fabric showed directional transport to a liquid, it prevented liquids of higher surface tension from penetration, but allowed liquids of lower surface tension to permeate, from either side. The directional transport ability can be switched from one fluid to another simply by heating the fabric at an elevated temperature and then re-irradiating the fabric with UV light for required period of time. By attaching liquid drops vertically upwards to a horizontally-laid fabric, we further demonstrated that this novel directional fluid transport was an automatic process driven by surface property alone, irrespective of gravity's effect. This novel fabric may be useful for development of “smart” textiles and functional membranes for various applications

Wettability of Nanostructured Surfaces

There are many studies in literature concerning contact angle measurements on different materials/substrates. It is documented that textiles can be coated with multifunctional materials in form of thin films or nanoparticles to acquire characteristics that can improve the protection and comfort of the wearer. The capacity of oxide nanostructures to inhibit fungal development and neutralize bacteria is a direct consequence of their wetting behavior [1–6]. Moreover, the radical modification of wetting behavior of nanostructures from hydrophilic to hydrophobic when changing the pulsed laser deposition (PLD) ambient will be thoroughly discussed

Polímeros inteligentes. Informe de vigilancia tecnológica

Este informe de Vigilancia Tecnológica ha sido cofinanciado con Fondos FEDER y se ha realizado dentro del marco del Contrato Programa suscrito entre la Dirección General de Universidades e Investigación de la Comunidad de Madrid y la Universidad Carlos III de Madrid, con la colaboración del Parque Científico de Leganés que gestiona el Círculo de Innovación en Materiales, Tecnología Aeroespacial y Nanotecnología.Los sistemas poliméricos inteligentes o polímeros sensibles al estímulo son polímeros que en respuesta a ligeros cambios en su entorno, como temperatura, pH, luz, campo eléctrico o magnético, concentración iónica, moléculas biológicas, etc. sufren cambios drásticos en sus propiedades. En este informe de Vigilancia Tecnológica se ha planteado la clasificación de los polímeros inteligentes según tres puntos de referencia: · Atendiendo al estímulo que reciben, · Atendiendo a la respuesta que proporcionan o · Según el tipo de material polimérico. El interés por el comportamiento “inteligente” de los polímeros aparece mucho más tarde que en el caso de los materiales metálicos o cerámicos inteligentes. Durante las últimas dos décadas el papel desempeñado por los polímeros inteligentes tomó importancia rápidamente, debido a los resultados prometedores de las investigaciones que demostraban las propiedades útiles de algunos polímeros en aplicaciones practicas.Dirección General de Universidades e Investigación. Comunidad de Madrid. Universidad Carlos III de Madrid. Acción Innovadora Fondos FEDE

Design of self-repairable superhydrophobic and switchable surfaces using colloidal particles

The design of functional materials with complex properties is very important for different applications, such as coatings, microelectronics, biotechnologies and medicine. It is also crucial that such kinds of materials have a long service lifetime. Unfortunately, cracks or other types of damages may occur during everyday use and some parts of the material should be changed for the regeneration of the initial properties. One of the approaches to avoid the replacement is utilization of self-healing materials. The aim of this thesis was to design a self-repairable material with superhydrophobic and switchable properties using colloidal particles. Specific goals were the synthesis of colloidal particles and the preparation of functional surfaces incorporated with the obtained particles, which would exhibit a repairable switching behavior and repairable superhydrophobicity. In order to achieve these goals, first, methods of preparation of simple and functional colloidal particles were developed. Second, the behavior of particles at surfaces of easy fusible solid materials, namely, paraffin wax or perfluorodecane, was investigated