A label-free impedance cytometry platform for multi-functional and high-precision bacterial characterization

Area of Science:

• Microfluidics
• Biosensing
• Bacteriology

Background:

• Conventional bacterial detection methods face limitations due to bacterial size and variability.
• Rapid and sensitive bacterial analysis is crucial for clinical diagnostics, environmental monitoring, and food safety.

Purpose of the Study:

• To develop a label-free impedance cytometry platform for enhanced bacterial detection and characterization.
• To improve signal stability and detection sensitivity using a novel electrode and fluid dynamics design.

Main Methods:

• A microfluidic chip with a double-differential electrode configuration and sheath fluid-assisted vertical compression was designed.
• Dual-frequency (1.5 and 9 MHz) electrical profiling was performed at the single-cell level.
• Optimization of sheath-to-sample flow rate ratio to 2:1 was achieved for enhanced performance.

Main Results:

• The platform demonstrated a 37% enhancement in impedance amplitude for bacteria.
• Distinct electrical profiles allowed discrimination between Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis).
• Thermal viability was assessed by detecting an 11% diameter increase in heat-treated E. coli.
• Antimicrobial susceptibility testing showed a 15% diameter increase in E. coli within 20 min of polymyxin B (PMB) exposure.

Conclusions:

• The developed platform provides multi-functional and high-precision bacterial characterization.
• This technology offers a versatile tool for rapid microbiological analysis in clinical diagnostics and research.
• The label-free impedance cytometry approach significantly advances bacterial detection capabilities.