On-Chip Integration of Impedance Cytometry for Inline Optimization of Dielectrophoretic Separations on Multiple...

Area of Science:

• Biomedical Engineering
• Cell Biology
• Microfluidics

Background:

• Dielectrophoresis (DEP) is a microfluidic technique for cell separation based on electrical properties.
• Current DEP optimization methods use endpoint assays (fluorescence microscopy, flow cytometry), hindering further cell analysis.
• Single-cell impedance cytometry offers label-free quantification but faces challenges in low-conductivity media and cell capture.

Purpose of the Study:

• To develop an integrated microfluidic system for label-free cell separation and real-time analysis.
• To overcome limitations of existing methods for optimizing dielectrophoretic cell enrichment.
• To enable longitudinal studies and transplantation of separated cell fractions.

Main Methods:

• Utilized viscoelastic flows for elasto-inertial cell focusing to maintain DEP throughput and avoid bubbles.
• Integrated downstream impedance cytometry with maximized voltage for enhanced sensitivity in DEP media.
• Developed a multichannel system for automated optimization of dielectrophoretic enrichment of circulating tumor cells (CTCs).

Main Results:

• Maintained high throughput of dielectrophoretic separation while improving impedance signal-to-noise ratio.
• Prevented irreversible cell capture on electrodes, allowing for downstream analysis.
• Successfully demonstrated automated optimization for enriching live CTCs from pancreatic cancer cell cultures using impedance metrics.

Conclusions:

• The integrated system provides a label-free, real-time method for cell separation and analysis.
• This approach overcomes key limitations of traditional methods, enabling longitudinal studies.
• The technology holds promise for advancing cancer research, particularly in CTC isolation and characterization.