Bias-free pneumatic sample injection in microchip electrophoresis

Area of Science:

• Microfluidics
• Analytical Chemistry
• Biotechnology

Background:

• Microfluidic devices are crucial for miniaturized analytical systems.
• Accurate sample introduction is a key challenge in microfluidic separations.
• Existing injection methods like electrokinetic injection can introduce sampling bias.

Purpose of the Study:

• To develop a novel microfluidic chip with accurate metering and pneumatic sample injection.
• To overcome the limitations of electrokinetic injection in microchip electrophoresis.
• To demonstrate the capability for precise sample introduction and separation.

Main Methods:

• Development of a microfluidic chip utilizing polydimethylsiloxane (PDMS) and fluorocarbon (FC) film layers.
• Implementation of Y-shaped hydrophobic valves for controlled pneumatic injection.
• Utilizing hydrophobicity and wettability for pneumatic sample introduction.
• Performing microchip electrophoresis separation of fluorescein and dichlorofluorescein (DCF).

Main Results:

• Successful accurate metering of 10 nL solution volumes.
• Demonstrated pneumatic injection without sampling bias.
• Achieved baseline separation of fluorescein and dichlorofluorescein using a single power source.
• Validated the concept with pneumatic injection of a red ink solution.

Conclusions:

• The developed microfluidic chip enables accurate metering and bias-free pneumatic sample injection.
• This technology facilitates efficient electrophoretic separation in microchip devices.
• The pneumatic injection scheme offers a robust alternative for microfluidic sample handling.