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5556029 
Journal Article 
Extensional flow of low-viscosity fluids in capillary bridges formed by pulsed surface acoustic wave jetting 
Bhattacharjee, PK; Mcdonnell, AG; Prabhakar, R; Yeo, LY; Friend, J 
2011 
1 
New Journal of Physics
ISSN: 1367-2630 
IOP PUBLISHING LTD 
BRISTOL 
13 
023005 
English 
WOS:000287852800005 
Forming capillary bridges of low-viscosity (.10 mPa s) fluids is difficult, making the study of their capillary-thinning behavior and the measurement of the fluid's extensional viscosity difficult as well. Current techniques require some time to form a liquid bridge from the stretching of a droplet. Rapidly stretching a liquid bridge using these methods can cause its breakup if the viscosity is too low. Stretching more slowly allows the bridge to thin and break up before a suitable bridge geometry can be established to provide reliable and accurate rheological data. Using a pulsed surface acoustic wave to eject a jet from a sessile droplet, a capillary bridge may be formed in about 7.5 ms, about seven times quicker than current methods. With this approach, capillary bridges may be formed from Newtonian and non-Newtonian fluids having much lower viscosities-water, 0.04% by weight solution of high-molecular-weight (7 MDa) polystyrene in dioctyl phthalate and 0.25% fibrinogen solution in demineralized water, for example. Details of the relatively simple system used to achieve these results are provided, as are experimental results indicating deviations from a Newtonian response by the low-viscosity non-Newtonian fluids used in our study. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. 
Break-up; Bridge geometry; Current techniques; Demineralized water; Dioctyl phthalate; Extensional flows; Extensional viscosity; High molecular weight; Liquid bridge; Low viscosity fluids; Newtonians; Non-Newtonian fluids; Rheological data; Sessile droplet; Simple system; Surface acoustic waves; Acoustic surface wave devices; Acoustic waves; Acoustics; Acoustoelectric effects; Drops; Esters; Flow measurement; Fluids; Non Newtonian flow; Non Newtonian liquids; Polystyrenes; Rheology; Viscous flow; Viscosity