(288e) Deflection Stability of an Electrohydrodynamic Liquid Bridge

We present results on the deflection stability of a dynamic electrohydrodynamic liquid bridge (ELB) as a new surface patterning technique [1] which provides high resolution (~ 100 nm) and high speed (> 1 m/s) simultaneously. A dynamic ELB is a thin electrified liquid filament emitted through a Taylor cone [2] and stabilized between two electrodes. For direct patterning purposes ELB is used like a pen to deploy liquids on moving surfaces. If the conditions are not selected correctly, charge on the surface of the filament [3] causes the filament to whip about as in electrospinning [4]. In order to achieve good spatial resolution and positioning accuracy, it is desired that ELB reaches to the surface straight without breaking up into droplets or deflecting from its centerline significantly. Therefore understanding how to control the oscillations of the filament is crucial for the ELB printing process. Using a parallel plate electrode configuration and a fast imaging system, we investigated the character of non-axisymmetric oscillations. We used image analysis to find instability growth rates under different electrode separations and showed that decreasing electrode separation decreases instability growth rate as well as amplitude of deflections. Comparison of the experimental growth rates with estimations from the existing stability theories [3,4] show that theories significantly overestimate the instability growth rates. References: [1] H.F. Poon, ?Electrohydrodynamic Printing,? PhD thesis, Department of Chemical Engineering, Princeton University (2002). [2] G.I. Taylor ?Disintegration of water drops in an electric field,? Proc. Roy. Soc. London, A, 280 383 (1964). [3] D.A. Saville, ?Stability of electrically charged viscous cylinders,? Phys. Fluids 14 1095 (1971). [4] M.P. Brenner, M.M. Hohman, M. Shin, G. Rutledge, ?Electrospinning and electrically forced jets. I. Stability theory,? Phys. Fluids, 13 2201 (2001).

Keywords: liquid bridges, patterning, stability *skorkut@princeton.edu