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1. Sketch-Based Tensor Decomposition for Non-Parametric Monitoring of Electrospinning Processes

   https://doi.org/10.1115/MSEC2020-8367  

   Segura, Luis Javier; Muñoz, Christian Narváez; Zhou, Chi; Sun, Hongyue (September 2020, ASME 2020 15th International Manufacturing Science and Engineering Conference)

   null (Ed.)

   Abstract Electrospinning is a promising process to fabricate functional parts from macrofibers and nanofibers of bio-compatible materials including collagen, polylactide (PLA), and polyacrylonitrile (PAN). However, the functionality of the produced parts highly rely on quality, repeatability, and uniformity of the electrospun fibers. Due to the variations in material composition, process settings, and ambient conditions, the process suffers from large variations. In particular, the fiber formation in the stable regime (i.e., Taylor cone and jet) and its propagation to the substrate plays the most significant role in the process stability. This work aims to designing a fast process monitoring tool from scratch for monitoring the dynamic electrospinning process based on the Taylor cone and jet videos. Nevertheless, this is challenging since the videos are of high frequency and high dimension, and the monitoring statistics may not have a parametric distribution. To achieve this goal, a framework integrating image analysis, sketch-based tensor decomposition, and non-parametric monitoring, is proposed. In particular, we use Tucker tensor-sketch (Tucker-TS) based tensor decomposition to extract the sparse structure representations of the videos. Additionally, the extracted monitoring variables are non-normally distributed, hence non-parametric bootstrap Hotelling T2 control chart is deployed to handle this issue during the monitoring. The framework is demonstrated by electrospinning a PAN-based polymeric solution. Finally, it is demonstrated that the proposed framework, which uses Tucker-TS, largely outperformed the computational speed of the alternating least squares (ALS) approach for the Tucker tensor decomposition, i.e., Tucker-ALS, in various anomaly detection tasks while keeping the comparable anomaly detection accuracy. 

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2. Thermochromic Fibers via Electrospinning

   https://doi.org/10.3390/polym12040842  

   Nguyen, Jimmy; Stwodah, Ratib M.; Vasey, Christopher L.; Rabatin, Briget E.; Atherton, Benjamin; D’Angelo, Paola A.; Swana, Kathleen W.; Tang, Christina (April 2020, Polymers)

   null (Ed.)

   Cholesteryl ester liquid crystals exhibit thermochromic properties related to the existence of a twisted nematic phase. We formulate ternary mixtures of cholesteryl benzoate (CB), cholesteryl pelargonate (CP), and cholesteryl oleyl carbonate (COC) to achieve thermochromic behavior. We aim to achieve thermochromic fibers by incorporating the liquid crystal formulations into electrospun fibers. Two methods of incorporating the liquid crystal (LC) are compared: (1) blend electrospinning and (2) coaxial electrospinning using the same solvent system for the liquid crystal. For blend electrospinning, intermolecular interactions seem to be important in facilitating fiber formation since addition of LC can suppress bead formation. Coaxial electrospinning produces fibers with higher nominal fiber production rates (g/hr) and with higher nominal LC content in the fiber (wt. LC/wt. polymer assuming all of the solvent evaporates) but larger fiber size distributions as quantified by the coefficient of variation in fiber diameter than blend electrospinning with a single nozzle. Importantly, our proof-of-concept experiments demonstrate that coaxially electrospinning with LC and solvent in the core preserves the thermochromic properties of the LC so that thermochromic fibers are achieved. 

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3. Experimental Assessment and Data-Driven Modeling of Three-Dimensional-Printed Conductive Patterns on Electrospun Substrates

   https://doi.org/10.1115/1.4069361  

   Zuniga, Pablo Andres; Zuniga-Navarrete, Christian; Segura, Stalin Jamil; Guo, Zipeng; Baidya, Sabur; Narvaez-Munoz, Christian; Koehne, Jessica; Segura, Luis Javier (December 2025, Journal of Micro and Nano Science and Engineering)

   Abstract Flexible electronics (FE) have emerged as a key technology with applications in various fields, e.g., energy storage and bio-electronics. Electrospinning (ES), inkjet printing (IJP), and intense pulsed light (IPL), constitute a flexible multistage system capable to handle high customization requirements. The ES/IJP/IPL system is used for flexible substrate fabrication, conductive patterns printing, and sintering, respectively. Although the ES/IJP/IPL system seems to be suitable for on-demand FE devices manufacturing, the correlation of materials and process parameters of individual stages (i.e., ES/IJP/IPL) with the FE devices performance (i.e., conductivity) remains unexplored. Therefore, the objective of this paper is to evaluate the integration of ES, IJP, and IPL, for future production of high-performance FE devices. Various materials and process parameters are used to investigate their influence on the FE device resistivity, including different polyacrylonitrile (PAN) concentrations, voltage regimes, flow rates and the collector types in ES, and distinct number of ink layers in IJP. The study includes (1) an experimental assessment of the electrospun membrane morphology (e.g., fiber diameter) and ink coating characteristics (e.g., ink penetration) using scanning electron microscopy (SEM), and (2) a data-driven analysis through logistic regression (LR), Gaussian process (GP), and Bayesian neural network (BNN) classification models to predict FE conductive feasibility. The results indicate that membranes with larger fiber diameters benefit ink penetration, printed layer/multilayer consistency, and conductivity. This is corroborated with the classification models, where the number of printed layers, fiber diameter, and collector type, are identified as significant factors for accurately predicting conductive patterns feasibility. 

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4. A comparative study of porous and hollow carbon nanofibrous structures from electrospinning for supercapacitor electrode material development

   https://doi.org/10.1016/j.surfin.2021.101386  

   K Asare, MF Hasan (August 2021, Surfaces and interfaces)

   Co-axial electrospinning is an efficient technique to develop core-shell or hollow nanofibrous structures. In this study electrospun carbon nanofibers with three different morphologies, i.e. solid nanofibers with porous structure (P-ECNF), hollow nanofibers with solid wall (H-ECNF), and hollow nanofibers with porous wall (HP-ECNF) were developed through bicomponent electrospinning and co-axial electrospinning of polyacrylonitrile (PAN) and poly (methyl methacrylate) (PMMA) by varying proportion of the sacrificial PMMA. Through comparative electrochemical analyses, it is revealed that the primary factors for electrochemical performance, i.e. specific capacitance, of the electrospun carbon nanofibrous materials are mesopore volume and total pore volume. The hollow structure as well as ordered carbon structure and intact fiber structure also benefits electrolyte transfer and subsequent electrochemical performance but is secondary. Overall the porous carbon nanofibrous electrode material from electrospinning PAN/PMMA (50/50) solution (P-ECNF-50-50) outperformed those hollow and hollow-porous counterparts from co-axial electrospinning and demonstrated the largest specific capacitance due to the largest mesopore volume as well as the largest total pore volume. This electrode material also showed excellent cycling stability (without any loss of specific capacitance) after 3,000 cycles of charging and discharging. It even showed some increase of specific capacitance with cycling test due to its relatively large amount of micropores. 

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5. Fabrication and Customization of Highly Porous PLGA Membranes Utilizing Near‐Field Electrospinning, Thermal Transitions, and Multilayer Strategies

   https://doi.org/10.1002/adem.202400917  

   Na, Noori; Kim, Minju; Kim, Jungkyu; Chang, Jiyoung (November 2024, Advanced Engineering Materials)

   Polymer porous membranes are crucial in various applications, including water filtration, tissue engineering, and drug administration. Conventional far‐field electrospinning (FFES) is widely used for producing polymeric membranes due to its cost‐effectiveness, scalability, and flexibility in using many polymers. However, FFES has limitations in controlling pore form and size, as it produces randomly oriented fibers that lead to inconsistent and noncustomizable pore sizes. To address these limitations, this work combines near‐field electrospinning (NFES) with thermal treatment of polymer fibers and membranes. NFES offers more precise control over fiber placement and alignment, producing well‐defined fiber patterns with consistent and customizable pore sizes without compromising the thickness of membranes. By exploring the interplay between polymer behavior, thermal effects, and capillary action, the differences in pore area under various temperatures and fiber spacings are characterized. Additionally, this study investigates the influence of multilayer infusion on pore size and geometric arrangement by examining multilayer configurations stacked at various angles. The results indicate that increasing the number of layers leads to decreased pore size, while the alignment of infused fibers affects pore shape. This integrated approach enhances control over membrane characteristics, improving the performance and consistency of polymer porous membrane fabrication across various applications. 

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