Anne Schwarz

A roadmap on smart textiles

Though industrial exploitation of smart textile systems is still in its infancy, the technological implementation is increasing. This is the result of substantial research and development investments directed towards this emerging field. In order to stimulate the progress in smart textiles, emerging developments need to be identified and selectively strengthened. Hence, this issue reports on a three-dimensional roadmap on smart textiles. It aims at contributing to set future actions in research, education and technology development. Research activities and technological developments are mapped, barriers and drivers of technological, strategic and societal and economical origins are identified. Finally, recommendations are phrased on how to overcome barriers and to progress in the field of smart textiles.

Discharge characteristics of poly(3,4-ethylene dioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) textile batteries; comparison of silver coated yarn electrode devices and pure stainless steel filament yarn electrode devices

This paper investigates textile-based energy storage devices fabricated with poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as an electro-active polymer and conductive yarns as the electrodes. The conductive yarns are sewn into a textile substrate and then coated with PEDOT:PSS systematically. Two different sets of devices were made. A comparison of the devices made with silver coated polybenzoxazol filament yarns and the devices made with pure stainless steel filament yarns is performed. The devices were charged and their self-discharge was measured by voltage decay. A study of the influence of charging time on the decay and the effect brought by various load resistors on the voltage decay is also performed. In this research, the devices with electrodes of pure stainless steel filaments yarns performed better than the devices with silver coated yarns; this outcome has been reported as standard by various researchers.

Van Der Pauw method for measuring resistivities of anisotropic layers printed on textile substrates

Electrically conducting layers have been screen printed on woven textile substrates. Using the Van Der Pauw method for electrical resistivity measurements in thin layers, it was observed that the screen-printed layers showed anisotropic behavior. In order to be able to interpret the measurements correctly, a mathematical analysis of the measuring method has been established. From the experimental results one is then able to find the relation between the electrical resistivity in the warp versus the weft direction.

A study on the morphology of thin copper films on para-aramid yarns and their influence on the yarn’s electro-conductive and mechanical properties

The latest technological advances in new materials and devices enabled wearable systems to be created by utilizing textile solutions. These solutions require electro-conductive yarns as a basic component. Although the production of electro-conductive yarn is widely reported, research is still necessary to characterize them to advance their electro-conductive and mechanical properties. Hence, we served this need and characterized copper-coated para-aramid yarns produced by an in-house developed electroless deposition method. In this paper we present our investigation on the yarn’s copper layer characteristics after deposition. Furthermore, we looked, in depth, at the yarn’s electro-conductive properties before and after washing as well as their mechanical properties before and after copper deposition. We found a dependency of the copper layer morphology on its deposition time. This is directly correlated to the resulting layer thickness and hence to the yarn’s electro-conductive properties, demonstrating the autocatalytic nature of the coating process. Above that, the electro-conductive properties of the coated yarn linearly decrease with washing cycles. Furthermore, the copper coating impairs the yarn’s mechanical properties decreasing its specific stress at break by 30%.

Comparative study on the mechanical properties of elastic, electro-conductive hybrid yarns and their input materials

The development of electro-conductive yarns and the characterization of their conductive properties has gained importance over the past years. However, for their later application, not only the electro-conductive properties of the yarns are important, but also their mechanical characteristics. Hence, this paper presents an analysis of the mechanical behaviour of elastic, electro-conductive hybrid yarns. The yarns comprised an elastic core yarn and electro-conductive winding yarns. Studying the mechanical properties of the hybrid yarns, as well as their corresponding input yarns, it could be proven that the overall good strength and elongation behaviour of the hybrid yarns was depended on the properties of the input yarns, as well as on the yarns’ production parameters.

Smart Textiles: An Overview

This chapter introduces smart textiles and explains how textile materials and structures can be used as sensors, actuators, communication devices, energy sources and storage tools, and even processors. Conductive materials serve as the base for smart textiles. There are several advantages of using textiles as a substrate for smart functions; this chapter explains their important role in thermoregulation and highlights a smart suit for rescue workers.

Electrical circuit model of elastic and conductive yarns produced by hollow spindle spinning

Abstract The implementation of electronic textiles which are capable of being applied as electrodes, sensors or heating elements is crucial in several fields of application, ranging from automotive to sports, from rehabilitation to art and design. However, current electronic textiles often suffer from poor mechanical properties, low drape and unstable electroconductive characteristics. One possibility to overcome these shortcomings is to introduce the electroconductive properties at a fibre or yarn level by combining traditional fibres and yarns with metal wires or metalised yarns. In this paper, we describe the production of multicomponent yarns which combine electroconductive properties with elasticity, drape and mechanical strength. We discuss the electroconductive properties of the yarns produced with hollow spinning technology. An electrical model based on Kirchhoff’s law was designed and validated with the abovementioned measurements.

Steps Towards a Textile-Based Transistor: Development of the Gate and Insulating Layer

During recent years, intensive research has been carried out in the area of electronic textiles. There is an emerging trend to create garments that host electronic components embedded in the textile substrate, as well as electronic textiles made from yarns or fibers already possessing electronic properties. The creation of passive devices, such as textile electrodes that measure body parameters, has proved successful. However, there is a great need for the development of textiles possessing additional active functions. Accordingly, we investigated the possibility of developing a textile substrate possessing integrated switching and amplification functions by depositing parts of an organic thin-film transistor on fibrous substrates of varying geometries and origins. This article relates the initial steps we employed to develop a textile-based thin-film transistor. It reports the development of a gate layer from the deposition of electroless copper, as well as the deposition of a polyimide dielectric layer using dip coating. Further, it discusses the layer’s properties in terms of thickness and electrical characteristics. A copper layer of 350 nm thickness deposited on polyester tape and polyamide fibers displayed excellent electro-conductive properties. A smooth gate dielectric layer was achieved with a polyimide concentration of 15 w% and a withdrawal speed of 50 mm/min. As a result, optimum conditions for producing thin functional gate and dielectric layers were found. The transistor properties, the deposition of a semiconductive layer, and the production of drain and source electrodes remain the focus of future work.

Current Distribution Modelling in Electroconductive Textiles

In this paper the current distribution within woven electroconductive textile sheets was investigated using a computer program written for the purpose of the simulations. An iterative method of solving very large resistor networks used to model textile sheets is discussed. The factors taken into account are the conductivity of the fibres, the contact resistance between the fibres, the contact angle a between the fibres and the electrodes, the size and the aspect ratio of the textile sheets. Maps of the current distribution generated by the program are included.

How to Equip Para-aramide Yarns with Electro-conductive Properties

Electro-conductive textiles are increasingly demanded in our today’s technology-driven world as they combine functionalities with high wearing comfort. Thus, they are, for instance, very suitable for being applied as electrodes integrated in clothing to measure biomedical parameters of a person. For this purpose they need to be modified to provide reliable electro-conductive properties. This can be achieved by depositing metals on the textile surface. Copper and gold are good materials to be used for this purpose because of their outstanding electro-conductive properties and possibility to deposit them in form of a thin layer on the surface of a fiber. In this work preference was given to copper. Hence, a thin layer of copper was deposited on synthetic yarns by means of an electroless deposition. This paper states the coating method for the copper deposition on para-aramide yarns. Further, it reports the first results on the characterization of the copper layer and the performance of the resulting yarns.