Manikandan Sivan

Nanofiber yarns offer unique opportunities for developing next-generation flexible materials that combine nanoscale functionality with macroscopic structural integrity. Their high surface-to-volume ratio, fine open porosity, and fibrous morphology enable applications in tissue engineering, drug delivery, filtration, sensors, energy storage, and functional textiles. However, the transition of nanofiber yarn technology from laboratory to industrial scale has been limited by low productivity and poor control over morphology, linear density, twist, and tensile strength. Here, we report a simple and robust method with strong scale-up potential for the continuous production of 100% nanofiber yarns using high-throughput needleless and collectorless alternating-current (AC) electrospinning. A plume of nanofibers generated from a rotating disc spinning-electrode is continuously deposited on a rotating drum and withdrawn through a spinning triangle, where a twirling device imparts controlled twist. Using this setup, nanofiber yarns composed of poly(vinyl butyral) (PVB), poly(ε-caprolactone) (PCL), polyamide 46 (PA46), and poly(vinyl alcohol) (PVA) were produced at speeds up to 55 m min⁻¹ with a 200 mm disc spinning-electrode. Scanning electron microscopy revealed densely packed nanofibrils within the yarn cross-sections and a dominant pore size around 1 µm. The yarns were braided and woven into scaffolds supporting cell adhesion and proliferation. This high-performance alternating-current electrospinning approach effectively bridges the gap between electrospun fibers—whose two of three characteristic dimensions reside in the nanoscale—and macroscopic textile manufacturing, thereby enabling a practical and scalable pathway for the industrial production of nanofiber yarns for biomedical and advanced material applications.

Nanofiber yarns offer unique opportunities for developing next-generation flexible materials that combine nanoscale functionality with macroscopic structural integrity. Their high surface-to-volume ratio, fine open porosity, and fibrous morphology enable applications in tissue engineering, drug delivery, filtration, sensors, energy storage, and functional textiles. However, the transition of nanofiber yarn technology from laboratory to industrial scale has been limited by low productivity and poor control over morphology, linear density, twist, and tensile strength. Here, we report a simple, scalable, and robust method for the continuous production of 100% nanofiber yarns using high-throughput needleless and collectorless alternating-current (AC) electrospinning. A plume of nanofibers generated from a rotating disc spinning-electrode is continuously deposited on a rotating drum and withdrawn through a spinning triangle, where a twirling device imparts controlled twist. Using this setup, nanofiber yarns composed of poly(vinyl butyral) (PVB), poly(ε-caprolactone) (PCL), polyamide 46 (PA46), and poly(vinyl alcohol) (PVA) were produced at speeds up to 55 m min⁻¹ with a 200 mm disc spinning-electrode. Scanning electron microscopy revealed densely packed nanofibrils within the yarn cross-sections and a dominant pore size around 1 µm. The yarns were braided and woven into scaffolds supporting cell adhesion and proliferation. This high-performance alternating-current electrospinning approach effectively bridges the gap between electrospun fibers—whose two of three characteristic dimensions reside in the nanoscale—and macroscopic textile manufacturing, thereby enabling a practical and scalable pathway for the industrial production of nanofiber yarns for biomedical and advanced material applications.

Fabrication of strong antibacterial composite nanofibrous yarns (CNYs) for suture applications by using common direct current electrospinning has been technologically challenging. In this work, we have demonstrated a more straightforward and facile approach to fabricate chlorhexidine (CHX)‐containing antibacterial nanofibrous sheaths wounded around a polyamide core yarn using a novel collectorless alternating‐current electrospinning approach. Scanning electron microscopy results showed that the nanofibrous envelope was completely wrapped around the core yarn for both polymers, polyurethane, and polyamide 6 (PA6), used in this study. High‐performance liquid chromatography after dissolving of the CNYs confirmed the presence of CHX in the yarns, while X‐ray photoelectron spectroscopy and Fourier‐transform infrared spectroscopy indicated that the amount is relatively low. The tensile properties of all the CNYs were better than of the core yarns and the CHX addition resulted in a lower envelope linear density and envelope adhesion force. Thermal gravimetric analysis showed that all CNYs are thermally stable within the temperature range of interest. Cytocompatibility tests with 3T3‐SA mouse fibroblast cells and antibacterial evaluations with Escherichia coli and Staphylococcus aureus showed that the CHX‐containing PA6‐based CNYs are biocompatible and have antibacterial properties, suggesting that these yarns can be used as functional and mechanically performant sutures.

Poly(ε‐caprolactone) (PCL) biopolymer nanofibers and micro‐fibers have been fabricated for the first time at the rates up to 14.0 g per hour using a needleless and collectorless alternating current electrospinning technique. By combining the ac‐voltage, “green” low toxicity glacial acetic acid (AA) as the solvent and sodium acetate (NaAc) as an additive, beadless PCL fibers with diameters tunable from 150 nm to 2000 nm, varying surface morphology and degree of self‐bundling are obtained. In this new approach, the addition of NaAc plays a crucial role in improving the spinnability of PCL solution and fiber morphology. NaAc reveals the concentration‐dependent effect on charge transfer and rheological properties of the PCL/AA precursor, which results in broader ranges of spinnable PCL concentrations and ac‐voltages suitable for rapid manufacturing of PCL‐based fibers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43232.