Solid State Phenomena Vol. 333

Abstract: Electrically conductive fibers are required for numerous fields of application in modern textile technology. They are of particular importance in the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. Elastic and electrically conductive filaments can be used as strain sensors for monitoring the mechanical loading of critical components. In order to produce such sensorial filaments, thermoplastic polyurethane (TPU) is compounded with carbon nanotubes (CNT) and melt spun. The mechanical performances of filaments produced at different spinning speeds and containing different amounts of CNT were tested. Furthermore, the correlation between the specific electrical resistance of the filaments and the mechanical strain were analyzed depending on the CNT-content and the spinning speed.

Abstract: Textile products are of great importance in the dissemination of newly developed communication devices and flexible electronics in conjunction with the advantages of covering the entire human body and being used all day long by all individuals in society. Various approaches have been developed to ensure the required electrical conductivity of textiles. Our research deals with melt spinning of carbon nanomaterial-based composites (CNCs) into electrically conductive filaments. By combining the various composite structures and property profiles with a conductive filler at high concentration, specific morphological structures can be achieved that offer a much higher potential for the development of new functional fibers for different smart textile applications.This study aims to produce nanocomposites from polyamide 6 (PA6) and polyethylene (PE) matrices with single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) by using a small-scale mixing device that provides short mixing time, and material savings in the first stage of the research.

Abstract: Smart textile behaviour encompasses changes over time, which are triggered upon a sensed stimulus. With a focus on dynamic qualities, this research sought to study how gradual and reversible transitions of smart textiles can be influenced by the activation variable – stimuli magnitude. Taking into account an analysis of different external stimuli for the same property change, the experimental work was conducted with Colour Change Materials, namely textiles screen printed with thermo, photo and hydrochromic pigments. The results attained demonstrate how stimuli magnitude can affect textile temporal expressions, in this case: hue, saturation and lightness, as well as pace change. In addition, different considerations also arose in respect to each stimulus’ energy type and interdependencies between stimuli types. Contributing to the understanding of dynamic qualities of smart textiles and chromic materials’ properties, this research also discusses further alternatives to explore textile behaviour towards new design possibilities for smart textiles as dynamic interfaces.

Abstract: The field of smart textiles has been steadily growing throughout the last decades. Wearables and garments with integrated electronics being one of the major sections of this area. One of the components that virtually any such product has is a power source. This paper focuses on one such option, which employs only non-toxic materials, which can be safely used in close proximity to human body. The paper builds on previously developed flexible textile aluminium-air battery prototype. New electrical measurements are provided, which show possibilities and limitations of the developed primary battery, as well as niches, where it can be used. This paper focuses on testing the battery in real-world application conditions, by repeatedly activating and deactivating it for short periods of time in order to test its useful life period. From that point useful practical applications can be determined, which take into account limitations of the battery. The measurements show that the battery is best suited for use in emergency and alarm systems, where the system is activated for relatively short period of time in order to change system’s state or transmit an alarm message. Some examples are smart diapers with smart monitoring capabilities and anti-drowning safety bracelets.

Abstract: This work aims to analyse the effect of plasma and alkaline pre-treatment to improve the adsorption of GNPs onto 100% cotton knits. For this purpose, in one approach, 2% GNPs were dispersed in an aqueous/ethyl-based solution, in another approach the same concentration of said nanoparticles were dispersed in different % of PEG (10%, 30% and 50%, w/ v). The functionalised samples with and without plasma pre-treatment were characterized by Field Emission Scanning Electron Microscopy (FESEM), Contact Angle, Ground State Diffuse Reflectance (GSDR), and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). Electrical and washability properties until 10th wash cycles were also evaluated. The dopped samples obtained semiconductor values, and the ones that received the plasma treatment became hydrophilic, which contributed to excellent absorption bands. However, it is necessary to carry out more in-depth studies that contribute not only to better adsorption, as well as an adequate anchoring of nanoparticles in textile substrates.

Abstract: UV bonding technology’s biggest limitation is the need of a transparent joining part to be able to cure the adhesive with an external light source. This is to be solved with ribbon fabrics made with polymer optical fibres (POF) which guide the UV light into the adhesive bond. On the basis of previously published experiments, a set of POF fabrics with different thread densities and weft materials is evaluated optically regarding the emitted UV light intensity and mechanically regarding the shear strength of the adhesive bonds. A factorial experiment plan indicates that higher tensile lap-shear strength comes with lower weft fineness and higher weft density. The maximum shear strength achieved was 8.3 MPa with potential room for improvement due to non-cohesive failure, relatively high weft densities and a comparatively low powered UV light source.

Abstract: Electric and electronic devices are mainly emitting electromagnetic radiation, and shielding from radiation is essential. Electrically conductive materials are suitable for radiation shielding applications. The designing of the textile material for the radiation shielding is challenging because of its open area and design. In general, more open area has transmit the radiations tend to lesser in shielding. Another factor is the laying angle of the textile material also plays important role beyond open area. In this study, the effect of laying angle and open area was analysed for effective utilization of conductive materials. The conductive nonwoven fabric was used to form as strips to simulate the various textile structures for shielding application. The Cu/Ni coated ultrathin polyester nonwoven fabric sample is taken to form two-layers strips and test for electromagnetic shielding effectiveness. In experimental design, three factors of strips which are strips laid angle, strip thickness, and gap between the strips are taken at three levels. The strip cover area and aperture area were calculated geomentrically for each design and significant difference on shielding effectiveness was noticed.

Abstract: The combination of sensor technology and textiles substantially extends the range of textile applications. Smart textiles, especially clothing, might increasingly be equipped with pressure sensors. They could be used in the sports or health sector to measure body activities or other activities which are close to the body. Therefore, it is essential to develop flexible sensors which allow to adapt to the properties of textile materials which are in contact with the body or surrounding it. In this paper a pressure sensor based on piezoresistive ink and conductive fabric with high flexibility is reported. Preliminary pressure sensors have been fabricated and tested on a universal testing machine. The sensors show to be functional, but also showing some aspects to improve, such as its hysteretic behaviour.

Abstract: This work is part of the European project MOTION (Interreg 2 Seas Mers Zeeën), which aims to develop an exoskeleton for children with cerebral palsy (CP). The developed exoskeleton is equipped with a smart garment in order to detect the stress (e.g. physical, physiological) during the rehabilitation. Five different sensors, i.e. electrocardiogram (ECG), respiratory rate (RR), pressure, galvanic skin response (GSR) and textile heat fluxmeter (THF), are integrated into this smart garment for stress detection. This paper focuses on the development of the textile heat fluxmeter. Several researchers used heat fluxmeters in physiological studies to measure the body heat exchanges with the environment. However, the non-permeability of such fluxmeter gives inaccurate measurements in wet condition. Innovative flexible textile heat fluxmeter may detect, analyze, and monitor the heat and mass transfers with minimum disturbance due to its porosity. Moreover, it is desirable to have flexible sensors when they need to be in contact with the human body, in which the flexibility and non-irritability requirements are of utmost importance.

Abstract: With the rise of electromagnetic radiation-based technologies, considerable attention has been drawn to developing and implementing innovative electromagnetic shielding materials. Carbon nanomaterials and conductive polymers have been appealing to both academia and industry as promising alternatives for the traditionally used metallic materials, owing to their lightness, flexibility, easy processability and resistance to corrosion, which are of special importance for textile applications. In this work, multiwalled carbon nanotubes (MWCNTs) and poly (3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) have been applied to cotton textile substrates by straightforward scalable dyeing and coating processes, respectively. These processes led to uniform and homogeneous coatings with distinct properties: the fabric coated with MWCNT presented higher thickness and lower loading of incorporated material than the textile coated with PEDOT:PSS (thickness: 995 μm vs. 208 μm; material loading: 9.4 wt.% vs. 70.7 wt.%). The electromagnetic shielding properties were outlined for each shielding textile in the frequency range of 5.85–18 GHz: an average shielding effectiveness of ~35.6 dB was obtained for MWCNT@tex, while PEDOT:PSS@tex reached ~38.3 dB. Thus, PEDOT:PSS provided enhanced radiation shielding with lower coating thickness, while the MWCNTs led to improved attenuation with less material usage. Shielding effectiveness values above 30 dB were obtained for both electromagnetic interference shielding textiles, which corresponds to an excellent classification for general use applications, such as casual clothing and maternity wear.