Using Electroosmotic Pumps to Control the Flow Velocity in Cotton Thread-Based µTADs

Area of Science:

• Microfluidics
• Analytical Chemistry
• Biomedical Engineering

Background:

• Passive microfluidic devices are crucial for point-of-care diagnostics.
• Microfluidic paper-based analytical devices (µPADs) have established flow control methods.
• Microfluidic thread-based analytical devices (µTADs) lack robust flow velocity control.

Purpose of the Study:

• To investigate electroosmotic pumping for flow velocity control in cotton thread-based µTADs.
• To demonstrate dynamic control over flow velocity and sample delivery sequences.
• To assess the potential for enhanced sensitivity in µTAD applications.

Main Methods:

• Utilized electroosmotic pumps integrated with cotton thread-based µTADs.
• Varied voltage magnitude and direction to modulate flow velocity.
• Demonstrated overcoming hydrophobic valves within the µTADs.
• Controlled sequential delivery of liquid samples in a multi-branch µTAD.

Main Results:

• Achieved a 13% decrease and a 106% increase in flow velocity using electroosmotic pumps.
• Successfully demonstrated dynamic, real-time control of flow velocity.
• Electroosmotic pumps effectively overcame hydrophobic valves in the thread-based devices.
• Precise control over liquid sample delivery sequences was achieved.

Conclusions:

• Electroosmotic pumping offers effective flow velocity control for cotton thread-based µTADs.
• This technique enables dynamic adjustments, enhancing device programmability.
• The method shows potential for improving detection sensitivity and enabling complex assays, such as lithium detection.