Yarns are key building blocks to construct complicated fibrous structures for diverse applications. Although carbon nanotube yarns have been fabricated by a few novel techniques, challenges still remain in processing other nano fibrous materials into yarns, especially during the fiber fabricating process. In this paper, we report a simple but efficient and versatile method to prepare well‐twisted continuous nanofiber yarns directly through an electrospinning process. The yarn electrospinning process used two oppositely charged electrospinning nozzles to generate a hollow nanofiber “cone” on an intermediate funnel collector. Continuous nanofiber yarns can be directly withdrawn from the “cone” apex, with up to 7400 turns per meter of twists inserted through the rotation of the funnel. The maximum yarn production rate is 5 m/min, and the yarn twist level and fiber orientation can be controlled by the funnel rotating speed and yarn withdrawal rate. The yarn tensile properties showed dependence on the twist level.
Small-diameter blood vessels (SDBVs) are still a challenging task to prepare due to the occurrence of thrombosis formation, intimal hyperplasia, and aneurysmal dilation. Electrospinning technique, as a promising tissue engineering approach, can fabricate polymer fibrous scaffolds that satisfy requirements on the construction of extracellular matrix (ECM) of native blood vessel and promote the adhesion, proliferation, and growth of cells. In this review, we summarize the polymers that are deployed for the fabrication of SDBVs and classify them into three categories, synthetic polymers, natural polymers, and hybrid polymers. Furthermore, the biomechanical properties and the biological activities of the electrospun SBVs including anti-thrombogenic ability and cell response are discussed. Polymer blends seem to be a strategic way to fabricate SDBVs because it combines both suitable biomechanical properties coming from synthetic polymers and favorable sites to cell attachment coming from natural polymers.