Pressure-driven sample injection with quantitative liquid dispensing for on-chip electrophoresis

Area of Science:

• Microfluidics
• Analytical Chemistry
• Biotechnology

Background:

• Traditional electrokinetic injection in microfluidic devices can be complex.
• Achieving precise, low-volume sample injection is crucial for quantitative electrophoretic analysis.
• Existing methods may lack simplicity and reproducibility for ultra-low volume dispensing.

Purpose of the Study:

• To develop and evaluate a novel, pressure-driven sample injection method for microchip electrophoresis.
• To simplify the sample injection procedure compared to electrokinetic methods.
• To assess the performance of the new method for quantitative and qualitative electrophoretic analyses.

Main Methods:

• A microfabricated device was designed with a
• metering chamber
• for quantitative dispensing and a
• hydrophobic passive valve
• with an air vent for injection.
• Pneumatic pressure was used to drive the injection of dispensed sample volumes.
• Electrophoretic separation of DNA fragments was performed using the developed injection method.

Main Results:

• The pressure-driven injection method demonstrated high reproducibility in dispensing, with a variation of 3.3% (n = 15).
• The method allowed for precise control over injection volumes, ranging from 0.45 to 4.0 nL.
• Electrophoretic separation efficiencies were evaluated across different injection volumes, showing suitability for quantitative analysis.

Conclusions:

• The developed pressure-driven sample injection method offers a simplified and precise alternative to electrokinetic injection.
• The use of a metering chamber and hydrophobic passive valve enables quantitative dispensing of ultra-low sample volumes.
• This technique is highly suitable for both quantitative and qualitative electrophoretic analyses on microfabricated devices.