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

Infrastructure for washable computing

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 1999.Includes bibliographical references (leaves 73-74).Wash-and-wear multilayer electronic circuitry can be constructed on fabric substrates, using conductive textiles and suitably packaged components. Fabrics are perhaps the first composite materials engineered by humanity; their evolution led to the development of the Jacquard loom, which itself led to the development of the modern computer. The development of fabric circuitry is a compelling closure of the cycle that points to a new class of textiles which interact with their users and their environments, while retaining the properties that made them the first ubiquitous "smart material". Fabrics are in several respects superior to existing flexible substrates in terms of their durability, conformability, and breathability. The present work adopts a modular approach to circuit fabrication, from which follow circuit design techniques and component packages optimized for use in fabric-based circuitry, flexible all-fabric interconnects, and multilayer circuits. While maintaining close compatibility with existing components, tools, and techniques, the present work demonstrates all steps of a process to create multilayer printed circuits on fabric substrates using conductive textiles.by E. Rehmi Post.S.M

Smart textiles for improved quality of life and cognitive assessment

Smart textiles can be used as innovative solutions to amuse, meaningfully engage, comfort, entertain, stimulate, and to overall improve the quality of life for people living in care homes with dementia or its precursor mild cognitive impairment (MCI). This concept paper presents a smart textile prototype to both entertain and monitor/assess the behavior of the relevant clients. The prototype includes physical computing components for music playing and simple interaction, but additionally games and data logging systems, to determine baselines of activity and interaction. Using microelectronics, light-emitting diodes (LEDs) and capacitive touch sensors woven into a fabric, the study demonstrates the kinds of augmentations possible over the normal manipulation of the traditional non-smart activity apron by incorporating light and sound effects as feedback when patients interact with different regions of the textile. A data logging system will record the patient’s behavioral patterns. This would include the location, frequency, and time of the patient’s activities within the different textile areas. The textile will be placed across the laps of the resident, which they then play with, permitting the development of a behavioral profile through the gamification of cognitive tests. This concept paper outlines the development of a prototype sensor system and highlights the challenges related to its use in a care home setting. The research implements a wide range of functionality through a novel architecture involving loosely coupling and concentrating artifacts on the top layer and technology on the bottom layer. Components in a loosely coupled system can be replaced with alternative implementations that provide the same services, and so this gives the solution the best flexibility. The literature shows that existing architectures that are strongly coupled result in difficulties modeling different individuals without incurring significant costs. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

SMART FABRICS-WEARABLE TECHNOLOGY

Smart fabrics, generally regarded as smart Textiles are fabrics that have embedded electronics and interconnections woven into them, resulting in physical flexibility that is not achievable with other known electronic manufacturing techniques. Interconnections and components are intrinsic to the fabric therefore are not visible and less susceptible of getting tangled by surrounding objects. Smart fabrics can also more easily adapt to quick changes in the sensing and computational requirements of any specific application, this feature being useful for power management and context awareness. For electronic systems to be part of our day-to-day outfits such electronic devices need to conform to requirements as regards wear-ability, this is the vision of wearable technology. Wearable systems are characterized by their capability to automatically identify the activity and the behavioral status of their wearer as well as of the situation around them, and to use this information to adjust the systems' configuration and functionality. This write-up focused on recent developments in the field of Smart Fabrics and pays particular attention to the materials and their manufacturing techniques

Development and washing reliability testing of a stretchable circuit on knit fabric

The smart textiles and wearable technology markets are expanding tirelessly, looking for efficient solutions to create long-lasting products. The research towards novel integration methods and increasing reliability of wearables and electronic textiles (e-textiles) is expanding. One obstacle to be tackled is the washability and the endurance to mechanical stresses in the washing machine. In this article, different layering of thermoplastic polyurethane (TPU) films and knit fabrics are used to integrate three different designs of stretchable copper-based meander tracks with printed circuit boards. The various combinations are washed according to the ISO 6330-2012 standard to analyze their endurance. Results suggest that one meander design withstands more washing cycles and indicate that the well-selected layer compositions increase the reliability. Higher stretchability together with greater durability is accomplished by adding an extra meander-shaped TPU film layer

TOWARDS SYSTEMS ON CLOTH: THE DESIGN, MANUFACTURING, AND VALIDATION OF OPEN-SOURCE EMBROIDERED RESISTORS

This thesis is focused on advancing embroidered wearable electronics and textile electronics by creating open-source flexible resistors. Advancements in textile electronics could usher a new generation of smart devices that are entirely flexible. Current systems on cloth primarily use rigid components, which limits the flexibility and comfort of using the fabric devices. To advance this field, I propose a novel method of creating flexible electrical resistors with embroidery. To realize this technology, I created an open-source tool to create embroidery files for machine fabrication. This thesis details the methods and tools created for resistor fabrication. The resistors were tested to cover a range of conditions wearable electronic devices may be subjected to, then tested in an applied setting by being used in a touch sensing device. It is concluded that the embroidered resistors are a viable technology and warrant continued study, development, and use

A Flexible 2.45-GHz Power Harvesting Wristband with Net System Output from -24.3 dBm of RF Power

This paper presents a flexible 2.45-GHz wireless power harvesting wristband that generates a net dc output from a -24.3-dBm RF input. This is the lowest reported system sensitivity for systems comprising a rectenna and impedance-matching power management. A complete system has been implemented comprising: a fabric antenna, a rectifier on rigid substrate, a contactless electrical connection between rigid and flexible subsystems, and power electronics impedance matching. Various fabric and flexible materials are electrically characterized at 2.45 GHz using the two-line and the T-resonator methods. Selected materials are used to design an all-textile antenna, which demonstrates a radiation efficiency above 62% on a phantom irrespective of location, and a stable radiation pattern. The rectifier, designed on a rigid substrate, shows a best-in-class efficiency of 33.6% at -20 dBm. A reliable, efficient, and wideband contactless connection between the fabric antenna and the rectifier is created using broadside-coupled microstrip lines, with an insertion loss below 1 dB from 1.8 to over 10 GHz. A self-powered boost converter with a quiescent current of 150 nA matches the rectenna output with a matching efficiency above 95%. The maximum end-to-end efficiency is 28.7% at -7 dBm. The wristband harvester demonstrates net positive energy harvesting from -24.3 dBm, a 7.3-dB improvement on the state of the art.</p

Connection techniques of textile wires to the solid and flexible solar cells

In order to make better use of clean energy such as solar energy, textile on earth have the potential to be made into solar textiles. The commercial solar cells can be embedded between the textile layers by laminating to harvest energy for e-textile applications. Research about solar textiles is not mature enough, and many aspects of the problem need to be solved. However, connecting techniques of conductive textile wires to flexible and solid solar cells are not in-deep studied. In addition, solar textile products with these connection technologies must meet washable requirements. To solve the problem of connecting textile wires to flexible and solid solar cells in the production of solar textiles, this study proposes three connection techniques for solar textiles, which are tape, adhesive and stitching based on literature and experimental validation. The feasibility of tape and adhesive methods was analyzed by literature review and the feasibility of stitching method was verified by experiments. The stitching is unapplicable method for solid solar cells that are difficult to penetrate, but applicable for flexible solar cells. The machine-washing durability of solar textile which composed of solar cells with stitch-connected conductive textile wires was verified by experiments. First, the textile wires were joined to flexible solar cells by stitching with the sewing machine and then embedded between fabric layers with TPU-lamination to simulate real set up in e-textile application. The humidity stickers were attached to the surface of solar cells, and it was expected to present solar textile samples with or without water inside. After the machine-washing process is completed, the individual parts of the solar textile sample are disassembled by delamination. For stitching method, after 15 machine wash tests by household washing machines, the performance of the solar cells was hardly affected, and the internal water resistance of the samples was good. The delamination process verifies that the components of the solar textile can be disassembled and have the potential to be recycled. The feasibility of tape connections has been proven by previous studies. Flexible adhesives that have the potential to connect textile wires to solar cells are liste

The 3rd International Conference on the Challenges, Opportunities, Innovations and Applications in Electronic Textiles

This reprint is a collection of papers from the E-Textiles 2021 Conference and represents the state-of-the-art from both academia and industry in the development of smart fabrics that incorporate electronic and sensing functionality. The reprint presents a wide range of applications of the technology including wearable textile devices for healthcare applications such as respiratory monitoring and functional electrical stimulation. Manufacturing approaches include printed smart materials, knitted e-textiles and flexible electronic circuit assembly within fabrics and garments. E-textile sustainability, a key future requirement for the technology, is also considered. Supplying power is a constant challenge for all wireless wearable technologies and the collection includes papers on triboelectric energy harvesting and textile-based water-activated batteries. Finally, the application of textiles antennas in both sensing and 5G wireless communications is demonstrated, where different antenna designs and their response to stimuli are presented

A Flexible 2.45-GHz Power Harvesting Wristband with Net System Output from -24.3 dBm of RF Power

This is the final version. Available from IEEE via the DOI in this recordThis paper presents a flexible 2.45-GHz wireless power harvesting wristband that generates a net dc output from a -24.3-dBm RF input. This is the lowest reported system sensitivity for systems comprising a rectenna and impedance-matching power management. A complete system has been implemented comprising: a fabric antenna, a rectifier on rigid substrate, a contactless electrical connection between rigid and flexible subsystems, and power electronics impedance matching. Various fabric and flexible materials are electrically characterized at 2.45 GHz using the two-line and the T-resonator methods. Selected materials are used to design an all-textile antenna, which demonstrates a radiation efficiency above 62% on a phantom irrespective of location, and a stable radiation pattern. The rectifier, designed on a rigid substrate, shows a best-in-class efficiency of 33.6% at -20 dBm. A reliable, efficient, and wideband contactless connection between the fabric antenna and the rectifier is created using broadside-coupled microstrip lines, with an insertion loss below 1 dB from 1.8 to over 10 GHz. A self-powered boost converter with a quiescent current of 150 nA matches the rectenna output with a matching efficiency above 95%. The maximum end-to-end efficiency is 28.7% at -7 dBm. The wristband harvester demonstrates net positive energy harvesting from -24.3 dBm, a 7.3-dB improvement on the state of the art.Engineering and Physical Sciences Research Council (EPSRC