Automated Miniaturized Digital Microfluidic Antimicrobial Susceptibility Test Using a Chip-Integrated Optical Oxygen...

Area of Science:

• Biomedical Engineering
• Microfluidics
• Analytical Chemistry

Background:

• Antimicrobial susceptibility testing (AST) is crucial for guiding antibiotic treatment.
• Current AST methods can be time-consuming and require significant sample volumes.
• Digital microfluidics (DMF) offers a platform for miniaturized and automated biological assays.

Purpose of the Study:

• To develop and validate a novel DMF-based AST utilizing an integrated optical oxygen sensor.
• To enable in-situ, real-time monitoring of bacterial growth and oxygen consumption.
• To automate sample handling, dilution, and mixing for rapid AST.

Main Methods:

• Fabrication of a DMF device with an embedded oxygen-sensitive polymer film.
• Integration of an optical oxygen sensor for continuous dissolved oxygen (DO) measurement.
• Automated performance of sample dispensation, twofold serial dilution, and mixing for AST.
• Testing with *Escherichia coli* (E. coli) and various antibiotics (ampicillin, chloramphenicol, tetracycline).

Main Results:

• The DMF-integrated oxygen sensing film did not impede droplet manipulation or bacterial growth.
• Real-time monitoring of DO consumption during *E. coli* growth was achieved.
• Automated AST procedures were completed within 10 minutes.
• Minimum inhibitory concentration (MIC) values obtained from the DMF chip correlated well with standard methods.

Conclusions:

• The developed DMF platform provides a rapid, automated, and miniaturized solution for AST.
• The integrated optical oxygen sensor allows for continuous monitoring of bacterial metabolic activity.
• This technology reduces sample handling and volume requirements compared to traditional AST methods.