Green Conducting Cellulose Yarns for Machine-Sewn Electronic Textiles

Flexible and Durable Direct Ink Writing 3D-Printed Conductive Fabrics for Smart Wearables

Functional fabrics have broad applications in smart wearables, offering diverse functions, such as sensing, energy harvesting, and actuation. The use of 3D printing to deposit functional materials onto textile fabrics has emerged as a transformative approach in smart wearable development due to the advantages it offers. However, achieving the desired functionalities while maintaining the fabric's flexibility, wearing comfort, washability, and durability of the printed material remains a challenge. In this study, direct ink writing (DIW) 3D printing technology was employed to print polybutylene succinate (PBS) solutions containing carbon nanotubes (CNTs) onto two types of fabrics. Various properties of the printed fabrics were assessed to examine the influence of printing solutions, fabric structures, and postprinting processes on printing performance. The printed fabrics exhibited excellent electrical conductivity, mechanical strength, gauge factor, and stability under repeated strains. These characteristics highlight their potential for use in smart wearable devices such as strain- and motion-detecting sensors. Analysis of the printed fabric morphologies revealed that factors such as fiber content, yarn structure, and surface roughness of the substrate fabric, along with the rheological properties and surface tension of the printing solution, played key roles in determining the wetting and penetration behaviors of the solution on the substrate. The solution's ability to penetrate and bond with fibers provided the printed fabrics with enhanced washability and abrasion resistance, demonstrating the advantages of DIW printing technology in developing textile-based sensors for smart wearables. Additionally, by using biobased and biodegradable nontoxic Cyrene as the solvent for processing, the printed fabric is safer for smart wearables, and the process is more environmentally friendly than commonly used toxic solvents for PBS.

Implantable wireless suture sensor for in situ tendon and ligament strain monitoring

Tendon and ligament ruptures are prevalent, and severe sports injuries require surgical repair. In clinical practice, monitoring of tissue strain is critical to alert severe postoperative complications such as graft reinjury and loosening. Here, we present a sensor system that integrates a strain sensor and communication coil onto surgical silk sutures, enabling in situ monitoring and wireless readout of tissue strains via surgical implantation. The flexible sensor shows excellent adaptability to soft tissues, providing a strain monitoring range of 0 to 10% with a minimum detection threshold of 0.25% and maintaining stability more than 300,000 stretching cycles. The wireless sensor could be integrated with complex structures in surgical scenarios involving lateral collateral ligament injury and anterior cruciate ligament reconstruction, enabling distinct responses to graft stretching, reinjury, and loosening. Animal experiments demonstrate that the sensor can acquire real-time, clinical-grade strain data while exhibiting high biocompatibility. The sensor system shows considerable potential in evaluating preclinical implant performance and monitoring implant-related surgical complications.

Poly(benzodifurandione) Coated Silk Yarn for Thermoelectric Textiles

Thermoelectric textile devices represent an intriguing avenue for powering wearable electronics. The lack of air-stable n-type polymers has, until now, prevented the development of n-type multifilament yarns, which are needed for textile manufacturing. Here, the thermomechanical properties of the recently reported n-type polymer poly(benzodifurandione) (PBFDO) are explored and its suitability as a yarn coating material is assessed. The outstanding robustness of the polymer facilitates the coating of silk yarn that, as a result, displays an effective bulk conductivity of 13 S cm-1, with a projected half-life of 3.2 ± 0.7 years at ambient conditions. Moreover, the n-type PBFDO coated silk yarn with a Young's modulus of E = 0.6 GPa and a strain at break of εbreak = 14% can be machine washed, with only a threefold decrease in conductivity after seven washing cycles. PBFDO and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated silk yarns are used to fabricate two out-of-plane thermoelectric textile devices: a thermoelectric button and a larger thermopile with 16 legs. Excellent air stability is paired with an open-circuit voltage of 17 mV and a maximum output power of 0.67 µW for a temperature difference of 70 K. Evidently, PBFDO coated multifilament silk yarn is a promising component for the realization of air stable thermoelectric textile devices.

The Latest Advances in Ink-Based Nanogenerators: From Materials to Applications

Nanogenerators possess the capability to harvest faint energy from the environment. Among them, thermoelectric (TE), triboelectric, piezoelectric (PE), and moisture-enabled nanogenerators represent promising approaches to micro-nano energy collection. These nanogenerators have seen considerable progress in material optimization and structural design. Printing technology has facilitated the large-scale manufacturing of nanogenerators. Although inks can be compatible with most traditional functional materials, this inevitably leads to a decrease in the electrical performance of the materials, necessitating control over the rheological properties of the inks. Furthermore, printing technology offers increased structural design flexibility. This review provides a comprehensive framework for ink-based nanogenerators, encompassing ink material optimization and device structural design, including improvements in ink performance, control of rheological properties, and efficient energy harvesting structures. Additionally, it highlights ink-based nanogenerators that incorporate textile technology and hybrid energy technologies, reviewing their latest advancements in energy collection and self-powered sensing. The discussion also addresses the main challenges faced and future directions for development.

Metal-Assisted Injection Spinning of Ultra Strong Fibers from Megamolecular LC Polysaccharides

The molecular orientation of liquid crystalline (LC) hydrogels has the potential to induce a range of functionalities that can deliver great mechanical strength. Sacran is a supergiant LC polysaccharide isolated from the cyanobacterium Aphanothece sacrum with a high amount of anionic functional groups such as sulfates and carboxylates. In this article, ultra-strong sacran hydrogels and their dried fibers were produced by cross-linking under injection flow with trivalent metal ions such as Al3+, Cr3+, Fe3+, In3+, and rare-earth metal ions such Er3+ and Sr3+. Crossed-polarizing microscopy and X-ray diffraction imaging revealed a uniaxial molecular orientation in the LC gel fiber, resulting in outstanding mechanical characteristics.

Impact of doping on the mechanical properties of conjugated polymers

Conjugated polymers exhibit a unique portfolio of electrical and electrochemical behavior, which - paired with the mechanical properties that are typical for macromolecules - make them intriguing candidates for a wide range of application areas from wearable electronics to bioelectronics. However, the degree of oxidation or reduction of the polymer can strongly impact the mechanical response and thus must be considered when designing flexible or stretchable devices. This tutorial review first explores how the chain architecture, processing as well as the resulting nano- and microstructure impact the rheological and mechanical properties. In addition, different methods for the mechanical characterization of thin films and bulk materials such as fibers are summarized. Then, the review discusses how chemical and electrochemical doping alter the mechanical properties in terms of stiffness and ductility. Finally, the mechanical response of (doped) conjugated polymers is discussed in the context of (1) organic photovoltaics, representing thin-film devices with a relatively low charge-carrier density, (2) organic thermoelectrics, where chemical doping is used to realize thin films or bulk materials with a high doping level, and (3) organic electrochemical transistors, where electrochemical doping allows high charge-carrier densities to be reached, albeit accompanied by significant swelling. In the future, chemical and electrochemical doping may not only allow modulation and optimization of the electrical and electrochemical behavior of conjugated polymers, but also facilitate the design of materials with a tunable mechanical response.

A Sewing Approach to the Fabrication of Eco/bioresorbable Electronics

Eco/bioresorbable electronics represent an emerging class of technology defined by an ability to dissolve or otherwise harmlessly disappear in environmental or biological surroundings after a period of stable operation. The resulting devices provide unique capabilities as temporary biomedical implants, environmental sensors, and related systems. Recent publications report schemes to overcome challenges in fabrication that follow from the low thermostability and/or high chemical reactivity of the eco/bioresorbable constituent materials. Here, this work reports the use of high-speed sewing machines, as the basis for a high-throughput manufacturing technique that addresses many requirements for these applications, without the need for high temperatures or reactive solvents. Results demonstrate that a range of eco/bioresorbable metal wires and polymer threads can be embroidered into complex, user-defined conductive patterns on eco/bioresorbable substrates. Functional electronic components, such as stretchable interconnects and antennas are possible, along with fully integrated systems. Examples of the latter include wirelessly powered light-emitting diodes, radiofrequency identification tags, and temporary cardiac pacemakers. These advances add to a growing range of options in high-throughput, automated fabrication of eco/bioresorbable electronics.

Assembled one-dimensional nanowires for flexible electronic devices via printing and coating: Techniques, applications, and perspectives

The rapid progress in flexible electronic devices has necessitated continual research into nanomaterials, structural design, and fabrication processes. One-dimensional nanowires, characterized by their distinct structures and exceptional properties, are considered essential components for various flexible electronic devices. Considerable attention has been directed toward the assembly of nanowires, which presents significant advantages. Printing and coating techniques can be used to assemble nanowires in a relatively simple, efficient, and cost-competitive manner and exhibit potential for scale-up production in the foreseeable future. This review aims to provide an overview of nanowire assembly using printing and coating techniques, such as bar coating, spray coating, dip coating, blade coating, 3D printing, and so forth. The application of assembled nanowires in flexible electronic devices is subsequently discussed. Finally, further discussion is presented on the potential and challenges of flexible electronic devices based on assembled nanowires via printing and coating.

Advances in Cellulose-Based Composites for Energy Applications

The various forms of cellulose-based materials possess high mechanical and thermal stabilities, as well as three-dimensional open network structures with high aspect ratios capable of incorporating other materials to produce composites for a wide range of applications. Being the most prevalent natural biopolymer on the Earth, cellulose has been used as a renewable replacement for many plastic and metal substrates, in order to diminish pollutant residues in the environment. As a result, the design and development of green technological applications of cellulose and its derivatives has become a key principle of ecological sustainability. Recently, cellulose-based mesoporous structures, flexible thin films, fibers, and three-dimensional networks have been developed for use as substrates in which conductive materials can be loaded for a wide range of energy conversion and energy conservation applications. The present article provides an overview of the recent advancements in the preparation of cellulose-based composites synthesized by combining metal/semiconductor nanoparticles, organic polymers, and metal-organic frameworks with cellulose. To begin, a brief review of cellulosic materials is given, with emphasis on their properties and processing methods. Further sections focus on the integration of cellulose-based flexible substrates or three-dimensional structures into energy conversion devices, such as photovoltaic solar cells, triboelectric generators, piezoelectric generators, thermoelectric generators, as well as sensors. The review also highlights the uses of cellulose-based composites in the separators, electrolytes, binders, and electrodes of energy conservation devices such as lithium-ion batteries. Moreover, the use of cellulose-based electrodes in water splitting for hydrogen generation is discussed. In the final section, we propose the underlying challenges and outlook for the field of cellulose-based composite materials.

Parsimonious methodology for synthesis of silver and copper functionalized cellulose

Metal nanomaterials, such as silver and copper, are often incorporated into commercial textiles to take advantage of their Antibacterial and antiviral properties. The goal of this study was to identify the most parsimonious method for the synthesis of silver, copper, or silver/copper bimetallic treated textiles. To accomplish this eight different methods were employed to synthesize silver, copper, and silver/copper functionalized cotton batting textiles. Using silver and copper nitrate as precursors, different reagents were used to initiate/catalyze the deposition of metal, including: (1) no additive, (2) sodium bicarbonate, (3) green tea, (4) sodium hydroxide, (5) ammonia, (6, 7) sodium hydroxide/ammonia at a 1:2 and 1:4 ratio, and (8) sodium borohydride. The use of sodium bicarbonate as a reagent to reduce silver onto cotton has not been used previously in literature and was compared to established methods. All synthesis methods were performed at 80 °C for one hour following textile addition to the solutions. The products were characterized by x-ray fluorescence (XRF) analysis for quantitative determination of the metal content and x-ray absorption near edge structure (XANES) analysis for silver and copper speciation on the textile. Scanning electron microscopy (SEM) with energy dispersive x-ray (EDX) and size distribution inductively coupled plasma mass spectrometry (ICP-MS) were used to further characterize the products of the sodium bicarbonate, sodium hydroxide, and sodium borohydride synthesis methods following ashing of the textile. For the silver treatment methods (1 mM Ag +), sodium bicarbonate and sodium hydroxide resulted in the highest amounts of silver on the textile (8900 mg Ag/kg textile and 7600 mg Ag/kg textile) and for copper treatment (1 mM Cu +) the sodium hydroxide and sodium hydroxide/ammonium hydroxide resulted in the highest amounts of copper on the textile (3800 mg Ag/kg textile and 2500 mg Ag/kg textile). Formation of copper oxide was dependent on the pH of the solution, with 4 mM ammonia and other high pH solutions resulting in majority of the copper on the textile existing as copper oxide, with smaller amounts of ionic-bound copper. The identified parsimonious methods will lend themselves to the efficient manufacturing of antibacterial and antiviral textiles, or the development of multifunctionalized smart textiles.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10570-023-05099-7.

New Insights to Design Electrospun Fibers with Tunable Electrical Conductive-Semiconductive Properties

Fiber electronics, such as those produced by the electrospinning technique, have an extensive range of applications including electrode surfaces for batteries and sensors, energy storage, electromagnetic interference shielding, antistatic coatings, catalysts, drug delivery, tissue engineering, and smart textiles. New composite materials and blends from conductive-semiconductive polymers (C-SPs) offer high surface area-to-volume ratios with electrical tunability, making them suitable for use in fields including electronics, biofiltration, tissue engineering, biosensors, and "green polymers". These materials and structures show great potential for embedded-electronics tissue engineering, active drug delivery, and smart biosensing due to their electronic transport behavior and mechanical flexibility with effective biocompatibility. Doping, processing methods, and morphologies can significantly impact the properties and performance of C-SPs and their composites. This review provides an overview of the current literature on the processing of C-SPs as nanomaterials and nanofibrous structures, mainly emphasizing the electroactive properties that make these structures suitable for various applications.

A Review on the Modification of Cellulose and Its Applications

The latest advancements in cellulose and its derivatives are the subject of this study. We summarize the characteristics, modifications, applications, and properties of cellulose. Here, we discuss new breakthroughs in modified cellulose that allow for enhanced control. In addition to standard approaches, improvements in different techniques employed for cellulose and its derivatives are the subject of this review. The various strategies for synthetic polymers are also discussed. The recent advancements in polymer production allow for more precise control, and make it possible to make functional celluloses with better physical qualities. For sustainability and environmental preservation, the development of cellulose green processing is the most abundant renewable substance in nature. The discovery of cellulose disintegration opens up new possibilities for sustainable techniques. Based on the review of recent scientific literature, we believe that additional chemical units of cellulose solubility should be used. This evaluation will evaluate the sustainability of biomass and processing the greenness for the long term. It appears not only crucial to dissolution, but also to the greenness of any process.

Advances in the Robustness of Wearable Electronic Textiles: Strategies, Stability, Washability and Perspective

Flexible electronic textiles are the future of wearable technology with a diverse application potential inspired by the Internet of Things (IoT) to improve all aspects of wearer life by replacing traditional bulky, rigid, and uncomfortable wearable electronics. The inherently prominent characteristics exhibited by textile substrates make them ideal candidates for designing user-friendly wearable electronic textiles for high-end variant applications. Textile substrates (fiber, yarn, fabric, and garment) combined with nanostructured electroactive materials provide a universal pathway for the researcher to construct advanced wearable electronics compatible with the human body and other circumstances. However, e-textiles are found to be vulnerable to physical deformation induced during repeated wash and wear. Thus, e-textiles need to be robust enough to withstand such challenges involved in designing a reliable product and require more attention for substantial advancement in stability and washability. As a step toward reliable devices, we present this comprehensive review of the state-of-the-art advances in substrate geometries, modification, fabrication, and standardized washing strategies to predict a roadmap toward sustainability. Furthermore, current challenges, opportunities, and future aspects of durable e-textiles development are envisioned to provide a conclusive pathway for researchers to conduct advanced studies.

Cross-Links-Entanglements Integrated Networks Contributing to Highly Resilient, Soft, and Self-Adhesive Elastomers with Low Hysteresis for Green Wearable Electronics

Green wearable electronics are attracting increasing attention to eliminate harmful byproducts generated by traditional devices. Although various degradable materials have been explored for green wearable electronics, the development of degradable elastomers with integrated characteristics of low modulus, self-adhesion, high resilient, and low hysteresis remains challenging. In this work, a degradable elastomer poly(1,8-octanediol-co-citrate-co-caprolactone) (POCL) is reported, in which a loosely cross-linked network contains plenty of entangled flexible chains. The coexistence of covalent cross-links and entanglements of long polymer chains endows the elastomer with good resilience and low hysteresis, in addition to low modulus and self-adhesion. Taking advantage of the unique mechanical properties, epidermal strain sensors based on the POCL elastomer were prepared, which exhibited good adhesion to human skin, high sensitivity, high response rate, and excellent fatigue resistance. We also fabricated stretchable electroluminescent devices using this degradable elastomer and demonstrated the recyclability of the nondegradable materials in the electronic device.

Conducting materials as building blocks for electronic textiles

ABSTRACT

To realize the full gamut of functions that are envisaged for electronic textiles (e-textiles) a range of semiconducting, conducting and electrochemically active materials are needed. This article will discuss how metals, conducting polymers, carbon nanotubes, and two-dimensional (2D) materials, including graphene and MXenes, can be used in concert to create e-textile materials, from fibers and yarns to patterned fabrics. Many of the most promising architectures utilize several classes of materials (e.g., elastic fibers composed of a conducting material and a stretchable polymer, or textile devices constructed with conducting polymers or 2D materials and metal electrodes). While an increasing number of materials and devices display a promising degree of wash and wear resistance, sustainability aspects of e-textiles will require greater attention.