Electrospinning: A whipping fluid jet generates submicron polymer fibers

Polymeric fibers with diameters in the range from 50 nm to 5 mum are produc ed by accelerating a fluid jet in an electric field, in a process known as "electrospinning." Here we show that an essential element of the process is a fluid instability, the rapidly whipping jet. The phenomena responsible f or the onset of whipping are revealed by a linear instability analysis that describes the jet behavior in terms of known fluid properties and operatin g conditions. The behavior of two competing instabilities, the Rayleigh mod e and the axisymmetric conducting mode, is also described. The results are summarized using operating diagrams, delineating regimes of operation in el ectrospinning, which are in good agreement with experimental observations. (C) 2001 American Institute of Physics.