Separating the Living from the Dead: An Electrophoretic Approach

Area of Science:

• Biophysics
• Microbiology
• Analytical Chemistry

Background:

• Cell viability studies are crucial across various scientific and industrial fields.
• Microfluidic electrokinetic (EK) devices offer effective platforms for discriminating microorganisms based on viability.
• Previous studies attributed live/dead cell discrimination in insulator-based EK (iEK) devices to dielectrophoretic effects.

Purpose of the Study:

• To present a method for continuous separation of live and dead Escherichia coli (E. coli) cells using an iEK device.
• To investigate the underlying electrophoretic effects responsible for cell discrimination.
• To establish a mathematical model for optimizing iEK separation parameters.

Main Methods:

• Characterization of electrophoretic migration of live and dead E. coli cells.
• Development of a mathematical model in COMSOL Multiphysics using cell property data.
• Experimental validation of continuous separation in a T-cross iEK channel.

Main Results:

• Successful continuous separation of live and dead E. coli cells was achieved.
• A separation resolution of 1.87 was obtained, demonstrating effective discrimination.
• The study identified linear and nonlinear electrophoresis as the primary mechanisms for cell discrimination.

Conclusions:

• Linear and nonlinear electrophoresis are key phenomena for discriminating live and dead cells in iEK devices under DC electric fields.
• Continuous electrophoretic assessments provide a valuable tool for microorganism discrimination, including viability assessments.
• This technique has broad applicability in fields requiring cell viability analysis.