Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Electrospun nanofibers are extensively studied and their potential applications are largely demonstrated. Today, electrospinning equipment and technological solutions, and electrospun materials are rapidly moving to commercialization. Dedicated companies supply laboratory and industrial-scale components and apparatus for electrospinning, and others commercialize electrospun products. This paper focuses on relevant technological approaches developed by research, which show perspectives for scaling-up and for fulfilling requirements of industrial production in terms of throughput, accuracy, and functionality of the realized nanofibers. A critical analysis is provided about technological weakness and strength points in combination with expected challenges from the market.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/mame.201200290

Industrial Upscaling of Electrospinning and Applications of Polymer Nanofibers: A Review

Electrospinning is attracting close interest as a versatile fabrication method for one dimensional mesostructured organic, inorganic and hybrid nanomaterials of controlled dimensions prepared as random or oriented continuous nanofibres with possibilities of ordered internal morphologies such as core–sheath, hollow or porous fibre, or even multichannelled microtube arrangements. The dimensionality, directionality and compositional flexibility of electrospun nanofibres and mats are increasingly being investigated for the targeted development of electrode and electrolyte materials, where the specific properties associated with nanoscale features such as high surface area and aspect ratios, low density and high pore volume allow performance improvements in energy conversion and storage devices. We present here a review on the application of electrospinning for the design and fabrication of architectured, nanofibrous materials for dye sensitised solar cells, fuel cells, lithium ion batteries and supercapacitors, with particular emphasis on improved energy and power density imparted by performance improvement to, inter alia, ionic conductivity, cyclability, reversibility, interfacial resistance and electrochemical stability, as well as mechanical strength, of electrospun electrode and electrolyte components.

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Electrospinning: designed architectures for energy conversion and storage devices

Advances in three-dimensional nanofibrous macrostructures via electrospinning

During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Electrospinning is a well-established and intensively investigated methodology, and is currently the only known technique that can fabricate continuous nanofibres. The major challenge associated with electrospinning is its production rate, compared with that of conventional fibre spinning. However, the understanding of the scale-up possibility of the electrospinning process is still in its infancy. Substantial up-scaling of electrospinning may pave the way for applications of nanofibre assemblies (i.e. yarns) not accessible otherwise in conventional textile processes, such as weaving, knitting and braiding. Here we summarize recent advances regarding the enhancement of electrospinning throughput with special emphasis on multiple jets from multi-needles and the free surface of polymer solutions.

Mass production of nanofibre assemblies by electrostatic spinning

In the textile industry, although there are several methods for obtaining sub-micro- or nanofibres, electrospinning perhaps is the most versatile process. Electrospinning has been recognized as a feasible technique for the fabrication of continuous polymeric nanofibre yarns desired in the textile industry. Various materials including polymers, composites, ceramics and metals have been successfully electrospun into nanofibres in recent years mostly in solution and some in the melt. Potential applications based on electrospun nanofibres as a new-generation material in the textile industry will be realized if suitable nanofibre yarns become available to textile processes like weaving, knitting and embroidery. In this review, we present, from a textile viewpoint, a comprehensive overview of processing technologies of polymeric nanofibres in the textile industry; however, the emphasis here is focused on electrospinning. In particular, we choose to concentrate on a detailed account of research activities on the yarns and fabrics composed of electrospun nanofibres. Our discussion is concluded with some personal perspectives on the future challenges for the development and optimization of yarns based on electrospun nanofibres.

Manufacturing technologies of polymeric nanofibres and nanofibre yarns

A Highly Stretchable and Sensitive Strain Sensor Based on Dopamine Modified Electrospun SEBS Fibers and MWCNTs with Carboxylation

Jet deposition in near-field electrospinning of patterned polycaprolactone and sugar-polycaprolactone core–shell fibres

Characterization of porous media is essential in a wide range of biomedical and industrial applications. Microstructural features can be probed non-invasively by diffusion magnetic resonance imaging (dMRI). However, diffusion encoding in conventional dMRI may yield similar signatures for very different microstructures, which represents a significant limitation for disentangling individual microstructural features in heterogeneous materials. To solve this problem, we propose an augmented multidimensional diffusion encoding (MDE) framework, which unlocks a novel encoding dimension to assess time-dependent diffusion specific to structures with different microscopic anisotropies. Our approach relies on spectral analysis of complex but experimentally efficient MDE waveforms. Two independent contrasts to differentiate features such as cell shape and size can be generated directly by signal subtraction from only three types of measurements. Analytical calculations and simulations support our experimental observations. Proof-of-concept experiments were applied on samples with known and distinctly different microstructures. We further demonstrate substantially different contrasts in different tissue types of a post mortem brain. Our simultaneous assessment of restriction size and shape may be instrumental in studies of a wide range of porous materials, enable new insights into the microstructure of biological tissues or be of great value in diagnostics.

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Feng-Lei Zhou

Papers

Mass production of nanofibre assemblies by electrostatic spinning

Manufacturing technologies of polymeric nanofibres and nanofibre yarns

A Highly Stretchable and Sensitive Strain Sensor Based on Dopamine Modified Electrospun SEBS Fibers and MWCNTs with Carboxylation

Jet deposition in near-field electrospinning of patterned polycaprolactone and sugar-polycaprolactone core–shell fibres

Multidimensional diffusion MRI with spectrally modulated gradients reveals unprecedented microstructural detail