Electrospinning Equipment: Multi-Focused Electrospinning System for Precise 2D Multilayer Membrane Fabrication

Electrospinning is a technique that utilizes the principles of electrostatics and hydrodynamics to fabricate nanofibers by applying high voltage to polymer solutions. Electrospinning machines have been widely used in this process. Due to the unique structure of nanofibers, this technology has been widely applied in fields such as food, medicine, and electronics, for applications like food packaging, medical patches, and electronic sensors. Traditional electrospinning devices generate randomly deposited nanofiber membranes through a single nozzle and a high-voltage power supply, which is suitable for large-scale production of filter membranes and protective clothing. However, with the increasing demand for precise fiber deposition and patterned structures, the traditional random deposition method can no longer meet the application requirements. Although advanced manufacturing systems such as near-field electrospinning (NFES) can achieve precise deposition of single fibers, they are limited by the small distance between the nozzle and the collector, making large-scale production difficult for electrospinning machines with such limitations. At the same time, multi-nozzle and needle-less electrospinning are suitable for large-scale production but cannot achieve precise deposition. Therefore, the development of an electrospinning technology that can precisely control the fiber deposition area has become a research hotspot. Recently, a research team from the Department of Electronics and Information Engineering at Korea University published the latest research results on a multi-focused electrospinning system in the journal Materials Today Advances. By optimizing the geometry and parameters of the multi-ring electrode array, the team successfully achieved precise control of the fiber deposition area and realized waste-free parallel fabrication of centimeter-scale 2D multilayer membranes with their improved electrospinning device. This achievement provides a new method for the application of electrospinning technology in fields such as biomedicine and is expected to promote the efficient production of products such as medical patches.

The preparation of this system is shown in Figure 1. The system consists of two high-voltage power supplies, an automatic syringe pump, a 3-DOF moving collector (XY-plane translation and Z-axis rotation), and an array of ring-electrodes. In traditional electrospinning (without focusing electrodes), the spun fibers disperse randomly on the collector. However, the application of focusing electrodes confines the fiber deposition to a smaller controllable area, as shown in Figure 1b. The combination of focusing electrodes and a moving collector facilitates the fabrication of various 2D structures, such as arrays of circular single-layer membranes, membranes in the form of letters, and multilayer membranes with different materials and geometries.

The research team conducted computer simulations on three different types of focusing electrodes (conical electrodes, two-ring electrodes, and multi-ring electrode arrays) to compare their electric field distributions and field lines. The results show that only when the multi-ring electrode array is used in a multi-nozzle focusing array device, the trajectories of the electric field lines can converge at the center of each nozzle-electrode device. In contrast, for the other two electrode configurations, the distribution of radial forces in the region between the nozzle-electrode devices cancels each other out, causing the charged liquid to be pushed in the opposite direction. This characteristic of the multi-ring electrode array makes it the best choice for the development of a multi-focused system.

Then, the geometric parameters of the multi-ring electrode array, including the ring electrode radius (RE), the distance between electrodes (DEE), the distance between the nozzle and the electrode array (DNE), and the distance between the electrode array and the collector (DEC​), were analyzed in detail through computer simulations and experiments. The influence of these parameters on the fiber deposition area was studied. For example, when the ring electrode radius (RE) is 6 cm, the fiber deposition area can be precisely controlled within a range of 2 cm to 10 cm, and the optimization of the electrode array significantly improves the material utilization rate and reduces waste.

The optimized electrode array was evaluated using three different polymer solutions (polyacrylonitrile (PAN), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP)). The results show that within the range of 3.5 kV to 9.5 kV, the diameter (dc​) of the deposition area can be adjusted from 2.30 cm to 9.83 cm, and the diameters of the deposition areas of the three different polymer solutions (PAN, PEO, PVP) change linearly with VNE​. Experiments show that by adjusting the voltage of the focusing array, precise control of the fiber deposition area can be achieved, with an efficiency of up to 95.88%, which is significantly better than the traditional electrospinning method.

In addition, this multi-focused electrospinning system integrates the XY translation and Z-axis rotation of the moving collector, combined with the adjustment of the focusing array voltage, to achieve real-time control of the fiber deposition area. For example, by changing the position of the collector and the voltage, complex 2D patterns with different line widths and multilayer membranes with adjustable thicknesses can be fabricated. This integrated control function has been reported for the first time in an electrospinning system.

By using three nozzle-focusing array devices in conjunction with a 3-DOF moving collector, the fabrication of various complex patterns was achieved. For example, by simultaneously using three different-colored PAN solutions and adjusting the RE​ and VNE​ of each focusing array, three circular membranes with different colors and sizes were successfully prepared. In addition, by rotating the collection platform, a three-layer membrane composed of different polymer layers (white PEO layer, blue PVP layer, and pink PAN layer) with different diameters and thicknesses was fabricated. Experiments show that this configuration can simultaneously fabricate multilayer membranes composed of different materials, and the area and thickness of each layer are controllable.

Through the multi-focused electrospinning system, combined with the translational and rotational movements of the collector, the parallel fabrication of multilayer membranes composed of different materials was achieved. Taking the preparation of a medical patch containing three different polymers (blue PVP2, pink PAN, and white PEO) as an example, the material of each patch was deposited within the target area with an average accuracy of over 90%. Specifically, the deposition area of patch i is 11.45 cm², the target area is 11.21 cm², and the accuracy is 98.90%; the deposition area of patch ii is 3.54 cm², the target area is 3.14 cm², and the accuracy is 88.89%; the deposition area of patch iii is 19.91 cm², the target area is 21.78 cm², and the accuracy is 91.38%. Such multilayer membranes can be directly deposited on medical-related substrates for the manufacture of medical patches, which has important practical application value.

In conclusion, this paper presents a multi-focused electrospinning system for producing centimeter-scale 2D electrospun patterns, which can consist of multilayer, multi-material membranes. Computer simulations and electrospinning experiments using various focusing electrode geometries demonstrate that a multi-ring electrode array is the most effective configuration when using multiple nozzle-focusing array sets. Voltage control of the focusing array successfully regulates the size of the deposition area for the three tested polymer solutions within a diameter range of 2 cm to 10 cm. 

Additionally, experiments suggest that altering the diameter of the ring electrodes in the focusing array can extend the control range of the deposition area while using voltage control. Moreover, the implementation of three nozzle-focusing array sets on a 3-DOF moving collector enables the system to fabricate complex patterns. This is mainly because the simultaneous control of the collector position and the focusing array voltage allows for real-time adjustment of the diameter of the deposition area. As the experimental results show, the system is capable of the parallel production of multiple circular membranes consisting of multiple layers of different materials, achieving an accuracy exceeding 90%. This level of accuracy is crucial for the production of medical patches, which require waste-free and precise manufacture of electrospun membranes on the centimeter-scale.

Article source: https://doi.org/10.1016/j.mtadv.2025.100563