CMOS Conductometric System for Growth Monitoring and Sensing of Bacteria

Area of Science:

• Biomedical Engineering
• Electrical Engineering
• Microbiology

Background:

• Escherichia coli (E. coli) poses significant public health risks.
• Accurate and sensitive detection of E. coli is crucial for food safety and clinical diagnostics.
• Existing methods for bacterial detection can be time-consuming and require specialized equipment.

Purpose of the Study:

• To design and implement a prototype complementary metal-oxide semiconductor (CMOS) conductometric integrated circuit (IC).
• To enable sensitive monitoring of bacterial colony growth and specific sensing of E. coli.
• To utilize T4 bacteriophages for the specific detection of E. coli.

Main Methods:

• Fabrication of a CMOS IC using a TSMC 0.35-μm process.
• Implementation of a conductometric system measuring sample resistance via a two-electrode setup.
• Integration of a current-to-frequency (I to F) conversion circuit for digital output.
• On-chip pulsewidth control for signal modulation.

Main Results:

• The CMOS sensor system demonstrated the ability to monitor very low initial concentrations of E. coli (4x10^2 to 4x10^4 CFU/mL).
• The system successfully recorded the interaction between E. coli and T4 bacteriophages.
• The prototype CMOS IC exhibited low power consumption (1.85 mW at 3.3 V).

Conclusions:

• The developed CMOS conductometric IC offers a sensitive and specific platform for E. coli detection.
• This technology has potential applications in real-time bacterial monitoring and diagnostics.
• The system's low power consumption makes it suitable for portable sensing devices.