The need for high-precision microprinting processes that are controllable, scalable, and compatible with different materials persists throughout a range of biomedical fields. Electrospinning techniques offer scalability and compatibility with a wide arsenal of polymers, but typically lack precise three-dimensional (3D) control. We found that charge reversal during 3D jet writing can enable the high-throughput production of precisely engineered 3D structures. The trajectory of the jet is governed by a balance of destabilizing charge-charge repulsion and restorative viscoelastic forces. The reversal of the voltage polarity lowers the net surface potential carried by the jet and thus dampens the occurrence of bending instabilities typically observed during conventional electrospinning. In the absence of bending instabilities, precise deposition of polymer fibers becomes attainable. The same principles can be applied to 3D jet writing using an array of needles resulting in complex composite materials that undergo reversible shape transitions due to their unprecedented structural control.

Colloidal electrospinning is identified as a powerful tool for the fabrication of nonwoven nanofiber webs with increased functionality by the introduction of functional fillers into the webs. However, the use of this method is still limited due to minimal material diversity, low concentration of fillers, difficulty in mass production, and process difficulties. In this paper, syringeless electrospinning is suggested as an excellent method for colloidal electrospinning. Since the polymeric solution is supplied from the container through rotating drums, this method is relatively free from the precipitation of fillers present in the polymeric solution. Syringeless electrospinning provides a higher production rate than needle‐based electrospinning with simple process control. The syringeless technique makes it possible to expand the scope of the method to various polymers and inorganic fillers with sufficiently high filler concentrations. Herein, nonwoven nanofiber webs with a diverse combination of polymers (polyacrylonitrile (PAN), thermoplastic polyurethane (TPU), and polyvinylpyrrolidone (PVP)) and fillers (silica, titania, zirconia, activated carbons, and metal‐organic framework (MOF) crystals) are presented. Nonwoven nanofiber webs comprising PAN and UiO‐66‐NH2 MOF crystal are prepared for detoxification of a nerve agent simulant, diisopropyl fluorophosphate (DFP), as a representative example of applications.

Anisotropic microstructures are utilized in various fields owing to their unique properties, such as reversible shape transitions or on-demand and sequential release of drug combinations. In this study, anisotropic multicompartmental microfibers composed of different polymers are prepared via charge reversal electrohydrodynamic (EHD) co-jetting. The combination of various polymers, such as thermoplastic polyurethane, poly(D,L-lactide-co-glycolide), poly(vinyl cinnamate), and poly(methyl methacrylate), results in microfibers with distinct compositional boundaries. Charge reversal during EHD co-jetting enables facile fabrication of multicompartmental microfibers with the desired composition and tunable inner architecture, broadening their spectrum of potential applications, such as functional microfibers and cell scaffolds with multiple physical and chemical properties.

Electrospinning has received a lot of attention in recent years because it can create nonwoven nanofiber webs with high surface area and porosity. However, the typical needle and syringe‐based electrospinning systems feature poor productivity that has limited their usefulness in the industrial field. Here, current developments in the creation of nanofibers employing nonconventional electrospinning methods, such as needleless electrospinning and syringeless electrospinning, are examined. These alternate electrospinning techniques, which are dependent on numerous polymer droplets of varied shapes, have the potential to match the productivity required for industry‐scale manufacturing of nanofibers. Additionally, they make it possible to produce nanofibers that are difficult to spin using traditional techniques, like electrospinning of colloidal suspensions.