Determining Particle Size and Position in a Coplanar Electrode Setup Using Measured Opacity for Microfluidic...

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Microfluidic impedance flow cytometry offers label-free, high-throughput single-cell analysis.
• Coplanar electrode cytometers face challenges with particle position sensitivity due to inhomogeneous electric fields.

Purpose of the Study:

• To develop a novel particle height compensation method for microfluidic impedance flow cytometry.
• To enable accurate particle sizing and height determination using minimal electrodes and multi-frequency analysis.

Main Methods:

• Utilized the correlation between measured electrical opacity and particle height.
• Employed a two-coplanar electrode system with multi-frequency impedance analysis.
• Validated the method with polystyrene beads (5-7 µm) and yeast cells.

Main Results:

• Achieved high accuracy in determining particle size (CVs of 5.8%, 4.0%, 2.9% for 5, 6, 7 µm beads).
• Successfully predicted bead height with 1.5 µm accuracy (8% of channel height).
• Demonstrated the method's applicability in flow cytometry using yeast cells.

Conclusions:

• The novel opacity-based method effectively compensates for particle height variations in flow cytometry.
• A simplified two-electrode system with multi-frequency analysis enhances ease-of-use and reduces instrumentation requirements.
• This approach holds promise for developing smaller, more accessible microfluidic cell analysis devices.