All-organic, conductive and biodegradable yarns from core-shell nanofibers through electrospinning

Electroless plating of premetalized polyamide fibers for stretchable conductive devices

A new approach was used to produce electrically conductive polyamide yarns, employing an electroless plating technique, which involved stabilizing silver nanoparticles on the surface of the yarn using Sn²⁺. First, the [Ag(NH₃)²]⁺ complex was reduced using Sn²⁺ to produce silver nanoparticle seed layers on the fiber surface, followed by a formaldehyde reduction. The nucleation and growth of silver nanoparticles on the fiber surface were observed through SEM images, demonstrating varying degrees of silver deposition depending on the silver concentration. This deposition variation was confirmed through XRD patterns, TGA data and UV-vis spectra. Additionally, XPS characterization showed the evolution of the chemical state of silver and tin during the silver reduction process. Electrical resistance revealed that the resistance per unit length of the yarn ranged from 3 ± 0.3 Ω cm^-1 to 70 ± 6 Ω cm^-1, depending on the silver concentration. The resulting silver-plated yarn was incorporated into a stretchable device, demonstrating stable resistance over multiple cycles. This method of fabricating conductive yarn has the potential to open up new possibilities in the design and manufacture of stretchable conductive devices for flexible electronics.

Modification and Functionalization of Fibers Formed by Electrospinning: A Review

The development of new materials with specific functionalities for certain applications has been increasing with the advent of nanotechnology. A technique widely used for this purpose is electrospinning, because control of several parameters involved in the process can yield nanoscale fibers. In addition to the production of innovative and small-scale materials, through structural, chemical, physical, and biological modifications in the fibers produced in electrospinning, it is possible to obtain specific properties for a given application. Thus, the produced fibers can serve different purposes, such as in the areas of sensors, catalysis, and environmental and medical fields. Given this context, this article presents a review of the electrospinning technique, addressing the parameters that influence the properties of the fibers formed and some techniques used to modify them as specific treatments that can be conducted during or after electrospinning. In situ addition of nanoparticles, changes in the configuration of the metallic collector, use of alternating current, electret fibers, core/shell method, coating, electrospray-coating, plasma, reinforcing composite materials, and thermal treatments are some of the examples addressed in this work. Therefore, this work contributes to a better comprehension of some of the techniques mentioned in the literature so far.

State-of-the-art review of advanced electrospun nanofiber yarn-based textiles for biomedical applications

The pandemic of the coronavirus disease 2019 (COVID-19) has made biotextiles, including face masks and protective clothing, quite familiar in our daily lives. Biotextiles are one broad category of textile products that are beyond our imagination. Currently, biotextiles have been routinely utilized in various biomedical fields, like daily protection, wound healing, tissue regeneration, drug delivery, and sensing, to improve the health and medical conditions of individuals. However, these biotextiles are commonly manufactured with fibers with diameters on the micrometer scale (> 10 μm). Recently, nanofibrous materials have aroused extensive attention in the fields of fiber science and textile engineering because the fibers with nanoscale diameters exhibited obviously superior performances, such as size and surface/interface effects as well as optical, electrical, mechanical, and biological properties, compared to microfibers. A combination of innovative electrospinning techniques and traditional textile-forming strategies opens a new window for the generation of nanofibrous biotextiles to renew and update traditional microfibrous biotextiles. In the last two decades, the conventional electrospinning device has been widely modified to generate nanofiber yarns (NYs) with the fiber diameters less than 1000 nm. The electrospun NYs can be further employed as the primary processing unit for manufacturing a new generation of nano-textiles using various textile-forming strategies. In this review, starting from the basic information of conventional electrospinning techniques, we summarize the innovative electrospinning strategies for NY fabrication and critically discuss their advantages and limitations. This review further covers the progress in the construction of electrospun NY-based nanotextiles and their recent applications in biomedical fields, mainly including surgical sutures, various scaffolds and implants for tissue engineering, smart wearable bioelectronics, and their current and potential applications in the COVID-19 pandemic. At the end, this review highlights and identifies the future needs and opportunities of electrospun NYs and NY-based nanotextiles for clinical use.