An integrated AC electrokinetic pump in a microfluidic loop for fast and tunable flow control.

Area of Science:

• Microfluidics
• Electrokinetics
• Lab-on-a-chip technology

Background:

• Microfluidic systems require precise fluid manipulation.
• Electrokinetic phenomena offer a method for pumping fluids at the microscale.
• Integrated pumping solutions are crucial for miniaturized devices.

Purpose of the Study:

• To design and evaluate an integrated electrokinetic micropump.
• To investigate the performance of the micropump with varying electrolyte concentrations.
• To explore the control of fluid flow direction using electrical signals.

Main Methods:

• Fabrication of a lab-on-a-chip device with interdigitated electrodes.
• Integration of the micropump into a microfluidic loop.
• Application of low voltage AC signals across a range of frequencies and amplitudes.
• Systematic testing with electrolyte solutions of varying ionic strengths.
• Utilizing an integrated micromixer for automated parameter variation.

Main Results:

• Continuous and reproducible pumping of electrolyte solutions was achieved.
• Pumping speeds up to 500 µm/s were recorded in narrow channels (20 µm deep, 100 µm wide).
• Optimal pumping performance was observed in the 1-10 kHz frequency range with low voltage.
• Reversal of pumping direction was demonstrated at higher frequencies (50-100 kHz).

Conclusions:

• The developed electrokinetic micropump is effective for precise fluid control in microfluidic systems.
• The device offers tunable flow rates and directionality, suitable for complex microfluidic applications.
• This technology enables automated studies on the impact of ionic strength on electrokinetic pumping.