Refinement of current monitoring methodology for electroosmotic flow assessment under low ionic strength conditions

Saucedo-Espinosa, Mario A.; Lapizco‐Encinas, Blanca H.

doi:10.1063/1.4953183

Cited by 41 publications

(54 citation statements)

References 38 publications

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“…The electrokinetic displacement of fluids takes place in, for example, zeta potential measurement via electric current monitoring35 and sample stacking via isotachophoresis36 etc. The electrokinetic co-flow of two or more fluids with dissimilar properties is often encountered in microfluidic mixing3738.…”

mentioning

confidence: 99%

Electrokinetic instability in microchannel ferrofluid/water co-flows

Song

Zhou

et al. 2017

Sci Rep

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Electrokinetic instability refers to unstable electric field-driven disturbance to fluid flows, which can be harnessed to promote mixing for various electrokinetic microfluidic applications. This work presents a combined numerical and experimental study of electrokinetic ferrofluid/water co-flows in microchannels of various depths. Instability waves are observed at the ferrofluid and water interface when the applied DC electric field is beyond a threshold value. They are generated by the electric body force that acts on the free charge induced by the mismatch of ferrofluid and water electric conductivities. A nonlinear depth-averaged numerical model is developed to understand and simulate the interfacial electrokinetic behaviors. It considers the top and bottom channel walls’ stabilizing effects on electrokinetic flow through the depth averaging of three-dimensional transport equations in a second-order asymptotic analysis. This model is found accurate to predict both the observed electrokinetic instability patterns and the measured threshold electric fields for ferrofluids of different concentrations in shallow microchannels.

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mentioning

confidence: 99%

Electrokinetic instability in microchannel ferrofluid/water co-flows

Song

Zhou

et al. 2017

Sci Rep

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“…Current monitoring is a technique developed to estimate

μ_{E O}

of a liquid and the

ζ_{w}

of a substrate. The zeta potential of the PDMS channels employed was characterized as

ζ_{w}

= ‐97±1 mV employing a refined current monitoring approach .…”

Section: Properties Of the 12 Fluorescent Polystyrene Particles Analymentioning

confidence: 99%

“…Briefly,

0true {\overset{⇀}{v}}_{italicEK}

for each particle type was measured with PIV at different electric fields and this data was used to obtain the

μ_{E K}

values for all particles. EOF was characterized independently in terms of

μ_{E O}

and

ζ_{w},

then, μ EP and

ζ_{p}

were estimated by using Eqs. –.…”

Section: Properties Of the 12 Fluorescent Polystyrene Particles Analymentioning

confidence: 99%

Assessment of submicron particle zeta potential in simple electrokinetic microdevices

2018

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The present communication illustrates the use of simple electrokinetic devices for the assessment of the zeta potential of submicron polystyrene particles. A combination of manual and automatic particle tracking was employed. This approach allows for characterizing particles in the same conditions and devices in which they can be separated, e.g. dielectrophoretic separations; making the resulting data readily applicable.

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“…Besides electrophoresis, EOF is used in variety of microfluidic applications such as pumping , micromixing , and cell sorting . Therefore, it is essential to characterize EOF in microfluidic channels and capillaries .…”

Section: Introductionmentioning

confidence: 99%

“…The EOF velocity is proportional to the applied electric field and the proportionality constant is termed as the EOF mobility. Current monitoring method is one of the most convenient methods of measuring EOF mobility in capillaries and microchannels . The basic principle of the current monitoring method is illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

Effect of surface conduction–induced electromigration on current monitoring method for electroosmotic flow measurement

2019

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Current monitoring method for measurement of EOF in microchannels involves measurement of time-varying current while an electrolyte displaces another electrolyte having different conductivity due to EOF. The basic premise of the current monitoring method is that an axial gradient in conductivity of a binary electrolyte in a microchannel advects only due to EOF. In the current work, using theory and experiments, we show that this assumption is not valid for low concentration electrolytes and narrow microchannels wherein surface conduction is comparable with bulk conduction. We show that in presence of surface conduction, a gradient in conductivity of binary electrolyte not only advects with EOF but also undergoes electromigration. This electromigration phenomenon is nonlinear and is characterized by propagation of shock and rarefaction waves in ion concentrations. Consequently, in presence of surface conduction, the current-time relationships for forward and reverse displacement in the current monitoring method are asymmetric and the displacement time is also direction dependent. To quantify the effect of surface conduction, we present analytical expressions for current-time relationship in the regime when surface conduction is comparable to bulk conduction. We validate these relations with experimental data by performing a series of current monitoring experiments in a glass microfluidic chip at low electrolyte concentrations. The experimentally validated analytical expressions for current-time relationships presented in this work can be used to correctly estimate EOF using the current monitoring method when surface conduction is not negligible.

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Refinement of current monitoring methodology for electroosmotic flow assessment under low ionic strength conditions

Cited by 41 publications

References 38 publications

Electrokinetic instability in microchannel ferrofluid/water co-flows

Electrokinetic instability in microchannel ferrofluid/water co-flows

Assessment of submicron particle zeta potential in simple electrokinetic microdevices

Effect of surface conduction–induced electromigration on current monitoring method for electroosmotic flow measurement

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