Measurement of electroosmotic and electrophoretic velocities using pulsed and sinusoidal electric fields

In this work, we explore two methods to simultaneously measure the electroosmotic mobility in microchannels and the electrophoretic mobility of micron‐sized tracer particles. The first method is based on imposing a pulsed electric field, which allows to isolate electrophoresis and electroosmosis at...

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Bibliographic Details
Published in:Electrophoresis 2017-04, Vol.38 (7), p.1022-1037
Main Authors: Sadek, Samir H., Pimenta, Francisco, Pinho, Fernando T., Alves, Manuel A.
Format: Article
Language:English
Subjects:
Channels
Computational fluid dynamics
Diffusion
Diffusion rate
Electric fields
Electricity
Electroosmosis - methods
Electroosmotic mobility
Electrophoresis
Electrophoresis - methods
Electrophoretic mobility
Exact solutions
Measurement methods
Microchannels
Microfluidic Analytical Techniques - methods
Models, Theoretical
Part III: Methodologies and Applications
Particle Size
Particle tracking
Particle tracking velocimetry
Polydimethylsiloxane
Polystyrene resins
Polystyrenes - chemistry
Rheology - methods
Temporal resolution
Tracer particles
Velocity measurement
Viscoelastic fluids
Viscoelasticity
Zeta‐potential measurement
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Summary:In this work, we explore two methods to simultaneously measure the electroosmotic mobility in microchannels and the electrophoretic mobility of micron‐sized tracer particles. The first method is based on imposing a pulsed electric field, which allows to isolate electrophoresis and electroosmosis at the startup and shutdown of the pulse, respectively. In the second method, a sinusoidal electric field is generated and the mobilities are found by minimizing the difference between the measured velocity of tracer particles and the velocity computed from an analytical expression. Both methods produced consistent results using polydimethylsiloxane microchannels and polystyrene micro‐particles, provided that the temporal resolution of the particle tracking velocimetry technique used to compute the velocity of the tracer particles is fast enough to resolve the diffusion time‐scale based on the characteristic channel length scale. Additionally, we present results with the pulse method for viscoelastic fluids, which show a more complex transient response with significant velocity overshoots and undershoots after the start and the end of the applied electric pulse, respectively.
ISSN:0173-0835
1522-2683
DOI:10.1002/elps.201600368