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Electrokinetic Properties of Microfluidic Substrates
Funding: DOE, Lockheed Martin, Cornell, ACS-PRF
Among the unique properties of microfluidic devices is the ability to move liquids via electroosmosis. When the solid-liquid interface acquires a surface charge, an electrical double layer is formed as ions in the electrolyte solution align preferentially based on their charge. When this occurs, an electric field applied parallel to the wall will induce fluid flow.

Modeling and predicting the electrokinetic properties of microfluidic substrates that lead to electroosmosis is inherently difficult. The surface charges are a function of chemical reactions and adsorption/desorption processes, many of which are not fully understood. Further, the electrical double layer is often nanometers thick, and bulk fluid properties typically do not apply close to the wall, where the highest charge density (and therefore most of the action) resides.

Our work on the electrokinetic properties of microfluidic substrates includes (1) experimental characterization of interface properties, (2) chemical modification of interface properties, and (3) analytical and numerical modeling of double layer phenomena.

Publications and Presentations on Electrokinetic Properties of Microfluidic Substrates

Connelly JT, Kondapalli S, Parker, J Kirby BJ, Baeumner AJ
"Micro total analysis system for virus detection:microfluidic pre-concentration coupled to liposome-based detection," Analytical and Bioanalytical Chemistry, accepted, 2011.

Kondapalli S, Connelly JT, Baeumner AJ, Kirby BJ
"Integrated microfluidic preconcentrator and immunobiosensor," Microfluidics and Nanofluidics, 2011. doi

PDF version of Tandon Kirby: Ambient Pressure Effects on the Electrokinetic Potential of Zeonor-Water Interfaces

Tandon VT, Kirby BJ
"Ambient Pressure Effects on the Electrokinetic Potential of Zeonor-Water Interfaces," Journal of Colloid and Interface Science, 361:381-387, 2011. doi

HTML version of Kirby: Micro- and Nanoscale Fluid Mechanics: Transport in Microfluidic Devices

Kirby BJ
"Micro- and Nanoscale Fluid Mechanics: Transport in Microfluidic Devices," Cambridge University Press, 2010.
click here for html version| Cambridge University Press

PDF version of Tandon Kirby: Transient zeta potential measuremnts in hydrophobic topas microfluidics substrates

Tandon VT, Bhagavatula S, Kirby BJ
"Transient Zeta Potential Measurements in Hydrophobic, TOPAS Microfluidic Substrates," Electrophoresis 30(15) 2656-2667, 2009. doi pdf

PDF version of Tandon V Bhagavatula SK Nelson WC Kirby BJ:
Zeta potential and electroosmotic mobility in microfluidic devices
fabricated from hydrophobic polymers: 1. The origins of charge

Tandon V, Bhagavatula SK, Nelson WC, Kirby BJ
"Zeta potential and electroosmotic mobility in microfluidic devices fabricated from hydrophobic polymers: 1. The origins of charge", Electrophoresis 29(5):1092-1101, 2008. doi pdf

PDF version of Tandon V Kirby BJ:
Zeta potential and electroosmotic mobility in microfluidic devices 
fabricated from hydrophobic polymers: 2. Slip and interfacial water structure

Tandon V, Kirby BJ
"Zeta potential and electroosmotic mobility in microfluidic devices fabricated from hydrophobic polymers: 2. Slip and interfacial water structure", Electrophoresis 29(5):1102-1114, 2008. doi pdf

Wilkes JO , with Birmingham SG, Kirby BJ, Cheng C-Y
"Fluid Mechanics for Chemical Engineers with Microfluidics and CFD," Prentice-Hall, 2005.
click here to go to text webpage

PDF version of Mela, van den Berg, Fintschenko, Cummings, Simmons, Kirby: The zeta potential of cyclo-olefin polymer microchannels and its effects on insulative (electrodeless) dielectrophoresis particle trapping devices

Mela P, van den Berg A, Fintschenko Y, Cummings EB, Simmons BA, Kirby BJ
"The zeta potential of cyclo-olefin polymer microchannels and its effects on insulative (electrodeless) dielectrophoresis particle trapping devices," Electrophoresis 26:1792-1799 (2005). doi pdf text

PDF version of Kirby, Hasselbrink: The zeta potential of microfluidic substrates. 1. Theory, experimental techniques, and effects on separations

Kirby BJ, Hasselbrink, Jr. EF
"The Zeta Potential of Microfluidic Substrates. 1. Theory, experimental techniques, and effects on separations," Electrophoresis, 25:187-202 (2004). doi pdf text

PDF version of Kirby, Hasselbrink: The zeta potential of microfluidic substrates. 2. Data for polymers

Kirby BJ, Hasselbrink, Jr. EF
"The Zeta Potential of Microfluidic Substrates. 2. Data for polymers," Electrophoresis, 25:203-213 (2004). doi pdf text

PDF version of Reichmuth, Kirby: Effects of ammonioalkyl sulfonate internal salts on electrokinetic micropump performance and reversed-phase HPLC separations

Reichmuth DS, Kirby BJ
"Effects of Ammonioalkyl sulfonate internal salts on electrokinetic micropump performance and Reversed-Phase HPLC separations," Journal of Chromatography A, 1013:93-101 (2003). doi pdf text

PDF version of Reichmuth, Chirica, Kirby: Increasing the performance of high-pressure, high-efficiency electrokinetic micropumps using zwitterionic solute additives

Reichmuth DS, Chirica GS, Kirby BJ
"Increasing the Performance of High-Pressure, High-Efficiency Electrokinetic Micropumps Using Zwitterionic Solute Additives," Sensors and Actuators B-Chemical, 92:37-43 (2003). doi pdf text

PDF version of Kirby, Wheeler, Zare, Fruetel, Shepodd: Programmable modification of cell adhesion and zeta potential in silica microchips

Kirby BJ, Wheeler AR, Zare RN, Fruetel JA, Shepodd TJ
"Programmable Modification of Cell Adhesion and Zeta Potential in Silica Microchips,"Lab On a Chip 3:5-10 (2003). doi pdf text

The evolution of electrokinetic potential observed at Zeonor-water interfaces as a function of time. The decay is fastest at low ambient pressures. (see ref at the journal website here).