A metallic needle is most often used in conventional electrospinning, where a point-plate electric field with nonuniform distribution is formed in single-needle electrospinning (SNE). Low flow rate in SNE has restricted the application of electrospinning on an industrial scale. Multiple needles have been introduced to enhance the flow rate. However, multiple needles make the electric field distribution much more complex. To resolve this problem, alternative electrospinning setups with more uniform electric field have to be developed. Flat spinnerets have been demonstrated to replace the needle in SNE setups. The operating diagrams for flat spinneret electrospinning (FSE) were determined and differed significantly from those for SNE. Nanofibers produced by FSE were more uniform than those from SNE. These differences were explained by the differences in electric fields simulated using finite element analysis (FEA). (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 2591-2598, 2010