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Ionic Origin of Electro-osmotic Flow Hysteresis.

ABSTRACT: Electro-osmotic flow, the driving of fluid at nano- or micro-scales with electric field, has found numerous applications, ranging from pumping to chemical and biomedical analyses in micro-devices. Electro-osmotic flow exhibits a puzzling hysteretic behavior when two fluids with different concentrations displace one another. The flow rate is faster when a higher concentration solution displaces a lower concentration one as compared to the flow in the reverse direction. Although electro-osmotic flow is a surface phenomenon, rather counter intuitively we demonstrate that electro-osmotic flow hysteresis originates from the accumulation or depletion of pH-governing minority ions in the bulk of the fluid, due to the imbalance of electric-field-induced ion flux. The pH and flow velocity are changed, depending on the flow direction. The understanding of electro-osmotic flow hysteresis is critical for accurate fluid flow control in microfluidic devices, and maintaining of constant pH in chemical and biological systems under an electric field.

SUBMITTER: Lim CY

PROVIDER: S-EPMC4770316 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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Ionic Origin of Electro-osmotic Flow Hysteresis.

Lim Chun Yee CY Lim An Eng AE Lam Yee Cheong YC

Scientific reports 20160229

Electro-osmotic flow, the driving of fluid at nano- or micro-scales with electric field, has found numerous applications, ranging from pumping to chemical and biomedical analyses in micro-devices. Electro-osmotic flow exhibits a puzzling hysteretic behavior when two fluids with different concentrations displace one another. The flow rate is faster when a higher concentration solution displaces a lower concentration one as compared to the flow in the reverse direction. Although electro-osmotic fl ...[more]

PMID: 26923197

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