Multi-jet mode electrospray for non-conducting fluids and multi-jet electrospinning with high-throughput using a coaxial grooved nozzle and two fluids

Abstract

Despite the promising features of liquid atomization, the electrospray technique currently has few practical applications, mainly because it is restricted to electrical conducting liquids and hampered by low throughput. To overcome these limitations, we have developed a multi-jet electrospray technique for non-conducting fluids. To obtain stable multi-jet operation, a grooved coaxial nozzle is employed to enhance the exterior electrical field. The multi-jet coaxial electrospray mechanism is identical to a single cone-jet coaxial electrospray, and multi-jet operation for a non-conducting fluid has the same features as a single cone-jet for a conducting liquid. The droplet size can be controlled by adjusting the flow rates, and the droplets are monodispersed with good stability and uniformity. To broaden the applications of the electrospinning technique, high throughput is one of the primary goals of many researchers. To overcome the throughput limitation, we have introduced coaxial grooved nozzles. By using a coaxial grooved nozzle and two fluids, one of which is polyethylene oxide (PEO), we are able to achieve stable multi-jet operation and relatively high throughput. The multi-jets are initiated by the multi-jet mode of the inner fluid, and share the total flow rate of the polymer solution. We have investigated the operating conditions for various flow rate combinations of two fluids. The morphology of the resulting nanofibers is uniform without bead formation. The fibers have an average diameter of about 350 nm.