Evaluation of a dielectrophoretic bacterial counting technique

Area of Science:

• Biophysics
• Electrokinetics
• Particle Analysis

Background:

• Dielectrophoresis (DEP) is an electrokinetic phenomenon involving particle migration in non-uniform alternating electric fields.
• DEP is influenced by the dielectric properties of particles and their suspending medium.
• Selective particle enumeration is crucial for various biological and chemical analyses.

Purpose of the Study:

• To describe an enumeration system based on dielectrophoresis for selective particle counting.
• To investigate the relationship between suspension concentrations and DEP collection for different particle types.
• To establish a calibration method for determining particle concentration using DEP.

Main Methods:

• Utilizing dielectrophoresis in non-uniform alternating electric fields.
• Analyzing polystyrene latex beads, pure bacterial samples, and bacterial mixtures (E. coli, S. marcescens, P. aeruginosa, B. subtilis).
• Establishing a calibration curve with polystyrene latex beads to relate DEP collection to particle concentration.

Main Results:

• Observed relationships between suspension concentrations and DEP collection for various particles.
• Successfully used polystyrene latex beads for calibration to determine particle concentration.
• Accurately predicted particle concentration in an unknown sample within a narrow deviation range (-6.2% to +6.9%).

Conclusions:

• The described dielectrophoresis system offers potential for selective particle enumeration.
• The system demonstrates accuracy in quantifying particle concentrations, including different cell types and viability states.
• DEP-based enumeration provides a reliable method for particle concentration determination with high precision.