Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads

In the last decade, interest in stretchable electronic systems that can be bent or shaped three-dimensionally has increased. The application of these systems is that they differentiate between two states and derive there from the requirements for the materials used: once formed, but static or permanently flexible. For this purpose, new materials that exceed the limited mechanical properties of thin metal layers as the typical printed circuit board conductor materials have recently gained the interest of research. In this work, novel electrically conductive textiles were used as conductor materials for stretchable circuit boards. Three different fabrics (woven, knitted and nonwoven) made of silver-plated polyamide fibers were investigated for their mechanical and electrical behavior under quasi-static and cyclic mechanical loads with simultaneous monitoring of the electrical resistance. Thereto, the electrically conductive textiles were embedded into a thermoplastic polyurethane dielectric matrix and structured by laser cutting into stretchable conductors. Based on the characterization of the mechanical and electrical material behavior, a life expectancy was derived. The results are compared with previously investigated stretchable circuit boards based on thermoplastic elastomer and meander-shaped conductor tracks made of copper foils. The microstructural changes in the material caused by the applied mechanical loads were analyzed and are discussed in detail to provide a deep understanding of failure mechanisms.EC/H2020/825647/EU/Re-Thinking of Fashion in Research and Artist collaborating development for Urban Manufacturing/REFREA

Washability of e-textiles: current testing practices and the need for standardization

Washability is seen as one of the main obstacles that stands in the way of a wider market success of e-textile products. So far, there are no standardized methods for wash testing of e-textiles and no protocols to comparably assess the washability of tested products. Thus, different e-textiles that are deemed equally washable by their developers might present with very different ranges of reliability after repeated washing. This paper presents research into current test practices in the absence of e-textile-specific standards. Different testing methods are compared and evaluated and the need for standardized testing, giving e-textile developers the tools to comparably communicate and evaluate their products’ washability, is emphasized

Textile Prototyping Lab - A Platform and Open Laboratory for the Promotion of Open Innovation and Networking between Research, Design and Industry

This paper introduces and discusses the Textile Prototyping Lab (hereinafter referred to as 'TPL'), which is a joint research project in its early stages of five organisations from the fields of textiles, electronic research, design and economics. It comprises the concept, design, installation and testing of a textile prototyping laboratory that is more open, flexible and interdisciplinary than other textile-related laboratories known to date. The core topic of the project is Open Innovation, which means research and development is conducted within the new context of sharing resources and results amongst the directly involved actors and the interested community consisting of industry, individual professionals and students. Thus the research and development activities relevant to the individual parties involved in this project are conducted jointly and made available beyond their own organisational boundaries. The concept is implemented by five partners with a sound expertise in their respective fields of action: The Saxon Textile Research Institute (STFI) and the Textile Research Institute Thuringia-Vogtland (TITV Greiz) - two leading German textile research institutes - are contributing their expertise in textile process chains, lightweight construction and Smart Textiles to the project. The Fraunhofer Institute for Reliability and Microintegration (IZM) supports the lab in the field of microelectronic integration into textile structures, but Fab Lab Berlin - with their expertise related to Open Innovation processes. weißensee academy of art berlin serves as the network coordinator and contributes its knowledge in textile design, design education and design research. This research project is part of futureTEX, an interdisciplinary competence network in which industry, scientific institutions and associations work together to actively shape the future of the German textile industry, fostering new interdisciplinary ideas, funded by the Federal Ministry of Education and Research in Germany. The infrastructure of TPL consists of a digitally supported central prototyping lab located at the weißensee academy of art berlin, supplemented by highly specialised facilities and 'focus labs‘ located at the partner institutes. A specifically developed software connects the different facilities and supports lean development processes. Additionally an extensive material library embodies and represents the textile expertise and serves as an analogue resource of references, information and inspiration in order to communicate the competence fields and technological possibilities of TPL. TPL connects different stakeholders from the textile sector and beyond promoting exchange among these. Diverse actors benefit from the competences of the TPL infrastructure and its network. The processes are adapted to serve different user types (e.g. industry, SMEs, start-ups, designers, engineers, developers, free-lancers, students). Thus TPL is an open and agile place where interdisciplinary practices and interests meet to foster quick and effective innovation processes within the extended field of textiles

Washable, Low-Temperature Cured Joints for Textile-Based Electronics

Low-temperature die-attaching pastes for wearable electronics are the key components to realize any type of device where components are additively manufactured by pick and place techniques. In this paper, the authors describe a simple method to realize stretchable, bendable, die-attaching pastes based on silver flakes to directly mount resistors and LEDs onto textiles. This paste can be directly applied onto contact pads placed on textiles by means of screen and stencil printing and post-processed at low temperatures to achieve the desired electrical and mechanical properties below 60 °C without sintering. Low curing temperatures lead to lower power consumption, which makes this paste ecological friendly

Sensitive brace recognises the right angle

Textile stretch sensor

Influence of Knitting and Material Parameters on the Quality and Reliability of Knitted Conductor Tracks

Many electronic textile (e-textile) applications require a stretchable basis, best achieved through knitted textiles. Ideally, conductive structures can be directly integrated during the knitting process. This study evaluates the influence of several knitting and material parameters on the resistance of knitted conductive tracks after the knitting process and after durability testing. The knitting speed proves to be of little influence, while the type of conductive thread used, as well as the knitting pattern both impact the resistance of the knitted threads and their subsequent reliability considerably. The presented research provides novel insights into the knitting process for conductive yarns and possible applications and shows that choosing suitable material and processing methods can improve the quality and robustness of knitted e-textiles