Scaling laws for jet pulsations associated with high-resolution electrohydrodynamic printing

Choi, H. K.; Park, Jang Ung; Park, O. Ok; Ferreira, Placid M.; Georgiadis, John G.; Rogers, John A.

doi:10.1063/1.2903700

Cited by 148 publications

(143 citation statements)

References 19 publications

(17 reference statements)

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“…Since these results have been used for reference in much of the later work (see, e.g., Refs. [31,32]), the good agreement displayed by this comparison shows that our results fit into the body of known data. Some of the pictures of Juraschek and Röllgen [29] suggest that the contact line of their menisci with the capillary tube may in some cases spread slightly along the outer surface of the tube.…”

Section: F Comparisons With Other Results In the Literaturesupporting

confidence: 72%

“…Here 0 is the permittivity of vacuum, L is the needle-to-collector distance, and E is the characteristic electric field induced by the applied voltage around the end of the needle [32,46]. The needle-to-collector distance is large compared to the diameter of the needle; the ratio L/D is about 18 in our experiments.…”

Section: Dimensionless Variables and Resultsmentioning

confidence: 82%

“…Similarly, they explain the decline of the frequency with increasing flow rate as an effect of the increase of liquid volume. Using the estimate of Marginean et al as a starting point, Choi et al [32] work out the modified scaling f ∼ B 3/4 E by replacing the radius of the contact line by the radius of the ejected ligament, which they estimate independently. Their result is included in Fig.…”

Section: F Comparisons With Other Results In the Literaturementioning

confidence: 99%

“…Briefly, in mode I the meniscus undergoes bursts of fast pulsed emissions (on the order of KHz) at rather low frequencies (tens of Hz), whereas in mode II the emissions are periodic and proceed at much higher frequencies (tens of KHz). More recent investigations of pulsating Taylor cones have been carried out by Marginean et al [30], Chen et al [31], and Choi et al [32], who proposed different scaling laws for the pulsation frequency and the masses delivered, while Marginean et al [33] introduced a classification of axial modes based on three periodic and stationary regimes interspersed with two chaotic regimes. Kim et al [34], Kang et al [35], and Lee et al [36] achieved improved control of the size and emission frequency of the droplets by using pulsed electric fields and partially classified the new dripping modes that appear in these conditions.…”

Section: Introductionmentioning

confidence: 99%

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Periodic emission of droplets from an oscillating electrified meniscus of a low-viscosity, highly conductive liquid

et al. 2015

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The generation of identical droplets of controllable size in the micrometer range is a problem of much interest owing to the numerous technological applications of such droplets. This work reports an investigation of the regime of periodic emission of droplets from an electrified oscillating meniscus of a liquid of low viscosity and high electrical conductivity attached to the end of a capillary tube, which may be used to produce droplets more than ten times smaller than the diameter of the tube. To attain this periodic microdripping regime, termed axial spray mode II by Juraschek and Röllgen [R. Juraschek and F. W. Röllgen, Int. J. Mass Spectrom. 177, 1 (1998)], liquid is continuously supplied through the tube at a given constant flow rate, while a dc voltage is applied between the tube and a nearby counter electrode. The resulting electric field induces a stress at the surface of the liquid that stretches the meniscus until, in certain ranges of voltage and flow rate, it develops a ligament that eventually detaches, forming a single droplet, in a process that repeats itself periodically. While it is being stretched, the ligament develops a conical tip that emits ultrafine droplets, but the total mass emitted is practically contained in the main droplet. In the parametrical domain studied, we find that the process depends on two main dimensionless parameters, the flow rate nondimensionalized with the diameter of the tube and the capillary time, q, and the electric Bond number B E , which is a nondimensional measure of the square of the applied voltage. The meniscus oscillation frequency made nondimensional with the capillary time, f , is of order unity for very small flow rates and tends to decrease as the inverse of the square root of q for larger values of this parameter. The product of the meniscus mean volume times the oscillation frequency is nearly constant. The characteristic length and width of the liquid ligament immediately before its detachment approximately scale as powers of the flow rate and depend only weakly on the applied voltage. The diameter of the main droplets nondimensionalized with the diameter of the tube satisfies d d ≈ (6/π ) 1/3 (q/f ) 1/3 , from mass conservation, while the electric charge of these droplets is about 1/4 of the Rayleigh charge. At the minimum flow rate compatible with the periodic regimen, the dimensionless diameter of the droplets is smaller than one-tenth, which presents a way to use electrohydrodynamic atomization to generate droplets of highly conducting liquids in the micron-size range, in marked contrast with the cone-jet electrospray whose typical droplet size is in the nanometric regime for these liquids. In contrast with other microdripping regimes where the mass is emitted upon the periodic formation of a narrow capillary jet, the present regime gives one single droplet per oscillation, except for the almost massless fine aerosol emitted in the form of an electrospray.

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Section: F Comparisons With Other Results In the Literaturesupporting

confidence: 72%

Section: Dimensionless Variables and Resultsmentioning

confidence: 82%

Section: F Comparisons With Other Results In the Literaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Periodic emission of droplets from an oscillating electrified meniscus of a low-viscosity, highly conductive liquid

et al. 2015

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“…The key advantage of EHD jet printing over other dispensing technologies is that by controlling the electric field strength droplets or liquid streams with a diameter much smaller than the nozzle size can be achieved. 71,72 Nozzle clogging is exacerbated by a reduction in the nozzle orifice and is one of the main causes of dispensing failure. Clogging in addition to the difficulties of nanoscale nozzle fabrication are some of the main challenges in any nanoscale dispensing technology.…”

Section: Electrohydrodynamic Jet Printingmentioning

confidence: 99%