Spinning the Future: The Convergence of Nanofiber Technologies and Yarn Fabrication

The rapid advancement in nanofiber technologies has revolutionized the domain of yarn materials, marking a significant leap in textile technology. This review dissects the nexus between cutting-edge nanofiber technologies and yarn manufacturing, aiming to illuminate the pathway toward engineering advanced textiles with unparalleled functionality. It first discusses the fundamentals of nanofiber assemblies and spinning techniques, primarily focusing on electrospinning, centrifugal spinning, and blow spinning. Additionally, the study delves into integrating nanofiber spinning technologies with traditional and modern yarn fabrication principles, elucidating the design principles that underlie the creation of yarns incorporating nanofibers. Twisting technologies are explored to examine how they can be optimized and adapted for incorporating nanofibers, thus enabling the production of innovative nanofiber-based yarns. Special attention is given to scalable strategies like centrifugal and blow spinning, which are spotlighted for their efficiency and scalability in fabricating nanofiber yarns. This review further analyses recently developed nanofiber yarn applications, including wearable sensors, biomedical devices, moisture management textiles, and energy harvesting and storage devices. We finally present a forward-looking perspective to address unresolved issues in nanofiber-based yarn technologies.

Detection of acoustic emission from nanofiber nonwovens under tensile strain - An ultrasonic test setup for critical medical device components

In the biomedical field, nanofiber materials are gaining increasing application. For material characterization of nanofiber fabrics, tensile testing and scanning electron microscopy (SEM) are established standards. However, tensile tests provide information about the entire sample without information about single fibers. Conversely, SEM images examine individual fibers, but cover only a small section near the surface of the sample. To gain information on failure at the fiber level under tensile stress, recording of acoustic emission (AE) is a promising method, but challenging due to weak signal intensity. Using AE recording, beneficial findings can be obtained even on "invisible" material failure without affecting tensile tests. In this work, a technology for recording weak ultrasonic AE of tearing nanofiber nonwovens is presented, which uses a highly sensitive sensor. Functional proof of the method using biodegradable PLLA nonwoven fabrics is provided. The potential benefit is demonstrated by unmasking significant AE intensity in an almost imperceptible bend in the stress-strain curve of a nonwoven fabric. AE recording has not yet been performed on standard tensile tests of unembedded nanofiber material intended for safety-related medical applications. The technology has the potential to enrich the spectrum of testing methods, even those not confined to medical field.

Fabrication of superhydrophobic nanofiber fabric with hierarchical nanofiber structure

Polyvinylidene fluoride (PVDF) nanofiber fabric, polyvinylidene fluoride/polyethylene glycol (PVDF/PEG) nanofiber fabric and polyvinylidene fluoride/polyethylene glycol/silicon dioxide (PVDF/PEG/SiO2) nanofiber fabrics are fabricated through a combination of electrospinning and weaving technology, inspired by the “lotus effect”. Nanofiber surfaces with a hierarchical nanofiber structure in the PVDF/PEG and PVDF/PEG/SiO2 nanofiber fabrics are formed by hydrolyzing PEG and doping with SiO2 nanoparticles, which is similar to the surface structure of a lotus leaf. The structures of these three fabrics are characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) and the mechanical properties and wettability are analyzed. The results show that the fiber structure of the PVDF/PEG composite nanofiber doped with SiO2 nanoparticles after water scrubbing is composed of many balls, which are formed by the embedding of the SiO2 nanoparticles in the polymer. Moreover, the “ball” is not only similar to the “hill” of a lotus leaf surface, but also similar to the “small thorn” on the “hill” because of the embossment of SiO2 nanoparticles on the “ball” surface. The ultimate tensile strength and failure strain of the PVDF/PEG/SiO2 nanofiber fabric are 92.12 MPa and 18.98%, respectively. The PVDF/PEG/SiO2 nanofiber fabric exhibits superhydrophobicity with a water contact angle of 173.2°.