An automated, high-throughput experimental system for induced charge electrokinetics.

Area of Science:

• Electrokinetics
• Surface Chemistry
• Microfluidics

Background:

• Standard induced charge electrokinetics (ICEK) theory often overpredicts experimental velocities.
• Discrepancies hinder the practical application of ICEK devices and indicate a gap in fundamental understanding.
• Electrokinetic phenomena are crucial for microfluidic and lab-on-a-chip systems.

Purpose of the Study:

• To develop and validate a new theoretical framework for ICEK.
• To create an automated experimental system for high-throughput ICEK data acquisition.
• To investigate the impact of dielectric surface modifications on ICEK flow behavior.

Main Methods:

• An automated experimental setup was designed for rapid ICEK data collection (approx. 1000 conditions/day).
• Experiments involved studying ICEK slip flows over electrodes coated with dielectric layers (SiO(2) and alkanethiol monolayers) of known thickness.
• A new theoretical model was developed incorporating surface chemistry effects of dielectric coatings.

Main Results:

• The developed theory achieved quantitative agreement with experimental data for SiO(2) coated surfaces across nearly 1000 conditions.
• Over 3000 additional experiments were conducted on alkanethiol monolayer coated surfaces.
• The study successfully correlated physico-chemical surface properties with ICEK flow characteristics.

Conclusions:

• The automated system enables efficient interrogation of factors influencing ICEK.
• The new theory accurately predicts ICEK velocities, accounting for dielectric surface modifications.
• This work facilitates the optimization of ICEK flows for microfluidic applications.