Low concentration E. coli O157:H7 bacteria sensing using microfluidic MEMS biosensor.

Area of Science:

• Microfluidics
• Biosensors
• MEMS Technology
• Electrochemistry

Background:

• Rapid and sensitive detection of foodborne pathogens like Escherichia coli O157:H7 is crucial for public health.
• Existing methods often require lengthy incubation periods or complex sample preparation.
• Microfluidic systems offer miniaturization and enhanced control for biological assays.

Purpose of the Study:

• To design, fabricate, and test a novel microfluidic MEMS biosensor.
• To achieve rapid and sensitive detection of low concentrations of Escherichia coli O157:H7.
• To integrate dielectrophoresis-based preconcentration with impedance sensing.

Main Methods:

• Fabrication of a microfluidic channel on a glass substrate using SU8 epoxy resist.
• Integration of gold electroplated electrodes for dielectrophoresis-based focusing.
• Development of interdigitated electrode arrays (IDEAs) functionalized with anti-E. coli antibodies for impedance sensing.
• Testing with bacterial samples across a frequency range of 100 Hz-10 MHz.

Main Results:

• The biosensor successfully concentrated bacterial cells using dielectrophoresis.
• Impedance changes were measured upon binding of E. coli to the antibody.
• Detection of bacterial concentrations as low as 39 CFU/ml was achieved.
• Total sensing time was reduced to 2 hours.

Conclusions:

• The developed microfluidic MEMS biosensor demonstrates high sensitivity and specificity for E. coli O157:H7 detection.
• The integrated dielectrophoresis focusing and impedance sensing approach is effective for low-concentration bacterial analysis.
• This technology holds promise for rapid point-of-care diagnostics and food safety applications.