Background: Renewable materials made using environmentally friendly processes are in high demand as a solution to reduce the pollution created by the fashion industry. In recent years, there has been a growing trend in research on renewable materials focused on bio-based materials derived from fungi. Results: Recently, fungal cell wall material of a chitosan producing fungus has been wet spun to monofilaments. This paper presents a modification for the fungal monofilament spinning process, by the development of a benign method, dry gel spinning, to produce continuous monofilaments and twisted multifilament yarns, from fungal cell wall, that can be used in textile applications. The fungal biomass of Rhizopus delemar, grown using bread waste as a substrate, was subjected to alkali treatment with a dilute sodium hydroxide solution to isolate alkali-insoluble material (AIM), which mainly consists of the fungal cell wall. The treatment of AIM with dilute lactic acid resulted in hydrogel formation. The morphology of the hydrogels was pH dependent, and they exhibited shear thinning viscoelastic behavior. Dry gel spinning of the fungal hydrogels was first conducted using a simple lab-scale syringe pump to inject the hydrogels through a needle to form a monofilament, which was directly placed on a rotating receiver and left to dry at room temperature. The resulting monofilament was used to make twisted multifilament yarns. The process was then improved by incorporating a heated chamber for the quicker drying of the monofilaments (at 30⁰C). Finally, the spinning process was scaled up using a twin-screw microcompounder instead of the syringe pump. The monofilaments were several meters long and reached a tensile strength of 63 MPa with a % elongation at break of 14. When spinning was performed in the heated chamber, the tensile strength increased to 80 MPa and further increased to 103 MPa when a micro-compounder was used for spinning. Conclusion: The developed dry gel spinning method shows promising results in scalability and demonstrates the potential for renewable material production using fungi. This novel approach produces materials with mechanical properties comparable to those of conventional textile fibers. 

Like skeletal muscles having a fibrous structure, conducting polymers can actuate upon electrical stimulation and can be shaped into fibers. Through textile assembly strategies of such fibers, complex actuating architectures are possible. However, state-of-the-art strategies using short pieces of yarn, which compel manual integration, are not fully taking advantage of textiles. To manufacture actuating textiles that best exploit textile properties like softness and pliability, and to enable production upscaling, a production of continuous, actuating fibers is presented here. These fibers are produced from commercial polyamide 6/6 filaments by first continuously dip-coating in a modified commercial poly(3,4−ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) dispersion before the electropolymerization of polypyrrole (PPy), where the fibers are withdrawn continuously through an electrolyte solution containing the pyrrole monomer. By employing a cyclic dip-coating with individual viscosity, drying temperature, and withdrawal speed for each layer, and by adjusting the tension, speed, and applied potential of the electropolymerization, their isotonic strain is enhanced threefold. Their specific tension, at 400 µN tex⁻¹, reaches slightly higher than human skeletal muscle fibers. Furthermore, these continuous actuating fibers produced on the meter are processable in an industrial knitting machine. This study anchors the development of textile muscle fibers for future textile muscles.

Textile actuators are at their infancy within the field of electromechanically active polymers. Crude fabric coatings as well as coated pieces of yarns can certainly perform actuation. However, they do not fully consider the capabilities of textile processes and structures. To allow for such possibilities, it is required to have a sufficient supply of processable functional fibres. The presented pilot line is designed to produce said functional fibres from commercial textile yarns. The three continuous processes composing the pilot line are: the layered dip coating using a PEDOT:PSS based solution, the electrodeposition of polypyrrole (PPy) onto the PEDOT coated fibres, and the ultraviolet cured dip coating of ionogels (i.e. dipping followed by UV curing). The continuous aspect of the processes is a key element for fabric manufacturing. Indeed, even the smallest usable fabric requires a substantial length of yarn. This is one of the reasons why the produced fibres were tested on an industrial knitting machine, the other reason being to test their processability. Additionally, a series of tests have been done on the fibres to obtain their conductive, tensile and, if applicable, actuative properties. Therefore, we present a pilot line producing knittable PEDOT coated fibres, textile muscle fibres and ionofibres.

The composites of Ni–Cu oxides with gadolinium doped ceria (GDC) are emerging as highly proficient anode catalysts, owing to their remarkable performance for solid oxide fuel cells operated with biogas. In this context, the nanocomposite catalysts (1 – x)NiO-xCuO/yGDC (x = 0.2–0.8; y = 1,1.3) are synthesized using a solid-state reaction route. The cubic and monoclinic structures are observed for NiO and CuO phases, respectively, while CeO2 showed cubic fluorite structure. The scanning electron microscopic images revealed a rise in the particle size with an increase in the copper and GDC concentration. The optical band gap values are calculated in the range 2.82–2.33 eV from UV–visible analysis. The Raman spectra confirmed the presence of vibration modes of CeO2 and NiO. The electrical conductivity of the nanocomposite anodes is increased as the concentration of copper and GDC increased and reached at 9.48 S cm–1 for 0.2NiO-0.8CuO/1.3GDC composition at 650 °C. The electrochemical performance of (1 – x)NiO-xCuO/yGDC (x = 0.2–0.8; y = 1,1.3)-based fuel cells is investigated with biogas fuel at 650 °C. Among all of the as-synthesized anodes, the fuel cell with composition 0.2NiO-0.8CuO/1.3GDC showed the best performance, such as an open circuit voltage of 0.84 V and peak power density of 72 mW cm–2. However, from these findings, it can be inferred that among all other compositions, the 0.2NiO-0.8CuO/1.3GDC anode is a superior combination for the high electrochemical performance of solid oxide fuel cells fueled with biogas.

Electronic textiles (E-textiles) are made using various materials including carbon nanotubes, graphene, and graphene oxide. Among the materials here, e-textiles are fabricated with reduced graphene oxide (rGO) coating on commercial textiles. rGO-based yarns are prepared for e-textiles by a simple dip coating method with subsequent non-toxic reduction. To enhance the conductivity, the rGO yarns are coated with poly(3,4-ethylene dioxythiophene): poly(styrenesulfonic acid) (PEDOT) followed by electrochemical polymerization of polypyrrole (PPy) as the electromechanically active layer, resulting in textile actuators. The rGO-based yarn actuators are characterized in terms of both isotonic displacement and isometric developed forces, as well as electron microscopy and resistance measurements. Furthermore, it is demonstrated that both viscose rotor spun (VR) and viscose multifilament (VM) yarns can be used for yarn actuators. The resulting VM-based yarn actuators exhibit high strain (0.58%) in NaDBS electrolytes. These conducting yarns can also be integrated into textiles and fabrics of various forms to create smart e-textiles and wearable devices. 

With the rise of ion-based devices using soft ionic conductors, ionotronics show the importance of matching electronic and biological interfaces. Since textiles are conformal, an essential property for matching interfaces, light-weight and comfortable, they present as an ideal candidate for a new generation of ionotronics, i-textiles. As fibers are the building blocks of textiles, ionically conductive fibers, named ionofibers, are needed. However, ionofibers are not yet demonstrated to fulfill the fabric manufacturing requirements such as mechanical robustness and upscaled production. Considering that ionogels are known to be conformal films with high ionic conductivity, ionofibers are produced from commercial core yarns with specifically designed ionogel precursor solution via a continuous dip-coating process. These ionofibers are to be regarded as composites, which keep the morphology and improve the mechanical properties from the core yarns while adding the (ionic) conductive function. They keep their conductivity also after their integration into conformal fabrics; thus, an upscaled production is a likely outlook. The findings offer promising perspectives for i-textiles with enhanced textile properties and in-air electrochemical applications.

Ions are prevalent within bioelectronics, as they are the main charge carriers in living systems. In contrast to electronic systems, ionic ones are closer to what can be found in our body; in muscles, neurons and nerves.

Textiles are a much-used biomedical material, both in vivo and in vitro due to its membrane character, highly efficient area, softness, biocompatibility and biodegradability. Modifying the physicochemical properties of the core or the surface of textile has been reported a countless number of times, but still, its use in a bioelectrical context is limited.

Fibres are the building blocks of textiles and what make textiles an architected class of material. Then ionically conductive fibres are of great interest.

Here, we show the preparation of iono-conductive textile fibres through the (semi-)continuous dip-coating of ionogel on the cellulose-based viscose.

Ionogels are composed of salts in liquid state and a 3-dimensional solid network, in our case an ionic liquid (IL), 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, commonly named EMIm OTf or EMIm Triflate, and a thiol acrylate network, allowing the mobility of the ions within or in/out of the gel. This specific combination is a first effort towards the development of ionic textile fibres and ionic smart textiles, as a variety of ILs with different cations and anions exists, potentially allowing a large number of different combinations.

We investigate how the coating of this ionogel affects the mechanical properties as well as the conductivity in AC or DC arrangement and their relation to temperature and humidity. Also, the thermal stability and sensitivity of degradation of the fibre system is studied.

Moreover, we introduce different textile structures, and potential applications directed to bioelectronics.

Electronic textiles’ primordial component are the connections that allow a circuit to be formed. As for today, the catalogue of conductive yarns is expanded to highly conductive metals such as copper, silver and steel, or electroconductive plastics composed of conductive polymers and electroconductive fillers such as metal particles or carbon allotropes.

Ionic liquids are also able to carry electrical charges, and their capacity to conduct electricity has yet to be investigated as a yarn component, e.g. an ion conducting coating.

Here, we report on attempts to coat ionic liquid-based click-ionogel on fibres, using thiol-ene reactions with the help of a photobase generator.

Ionogel precursors, composed of plurithiol precursors, acrylate monomers and a triflate ionic-liquid, are applied on yarn and then cured by UV irradiation, initiating the Michael reaction and creating the thiol-acrylate-triflate network around the yarn.

The aim of the present study is to prepare and characterise yarns coated with such ionogels, while developing a continuous yarn coating process.

Several different ionogel compositions and different yarn topologies are investigated, comparing their structure, electrical conductivity, mechanical properties, thermal stability, behaviour to chemical reagents, as well as the different surface tensions and interfacial interactions.

Textile processability is explored by the manufacture of simple fabrics.

An application for those ionic conductive coating is the ion supply for electroactive polymers coated yarns that currently rely on electrolytes. This novel coating will render the light-weight property of textile valuable, and therefore broadening their application as wearables.

Electrostatic graphene-grafted conductive yarns were prepared based on a scalable manufacturing method using conventional polyamide 6,6 (PA 6,6) multifilament yarns, common in the textile industry. Graphene oxide (GO) shows negative surface charge at any pH and PA 6,6 has an isoelectric point (IEP = pH|(zeta=0)) of 3.6. When GO and a polymer have the same charge sign, the resulting electrostatic interaction is repulsive and an electrostatic attraction does not arise until the polymer backbone has an oppositely charged sign compared to the GO nanosheets. To achieve this, yarns were modified with protonated chitosan (CS) followed by dip-coating with GO, resulting in electrostatic grafting of oxygen functional groups of GO onto amino groups of CS polymer chains. This coating process provides durable electrically conductive yarns (3 x 10(-2) to 4 x 10(-2) S m(-1)) with an excellent fastness to washing. It leads to the realization of graphene-grafted yarns as building elements of smart textiles, obtaining metal-free textile sensors. These yarns are capable of supplying power to an LED light using a 9 V battery and are expected to be an excellent candidate for feeding V-bed flat-knitting, Jacquard and raschel knitting machines. To achieve this, a wearable tactile sensor was designed and prepared using a flat-knitting machine and the sensor was characterized through electrical, mechanical, and electromechanical measurements.

Recently, graphene has been used to obtain (E)-textiles. From an industry-relevant perspective, it is essential to introduce a process that could be scaled-up. We applied a cost-effective dip-coating method using bio-sourced agents for chemical adsorption of graphene oxide (GO). Polyester and viscose woven fabrics were treated with an aqueous solution of glycerol (4 g.L-1) to overcome the electrostatic repulsion among fibers and GO and then dip-coated with a dispersion of GO. The results are homogeneous GO coating with one to a few layers of GO nano-sheets. Further, The GO was chemically reduced to rGO, by using tannic acid (10 g.L-1) as a bio-sourced reducing agent. This brings electrical conductivity to rGO nano-sheets having an electrical resistance of 2±1 and 10±4 kΩ/sq for polyester and viscose fibers respectively. Afterward, these E-textiles are both p-type and n-type doped, using nitrogen plasma treatment to prepare nitrogen-doped graphene as a p-type E-textile and electrochemical deposition of titanium on graphene as n-type Doped E-textiles. This increases the charge carrier density, consequently increasing the conductivity of the graphene. Doping rGO-modified textiles open up a visualization of the p-n junction fully-textile diodes and its further applications.