Microfluidic Ladder Circuit for Rapid Antimicrobial Susceptibility Testing
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Solution Overview
Problem
Current antibiotic susceptibility testing (AST) methods are time-consuming, typically taking 2-3 days, and often result in delayed antibiotic selection, contributing to the rise of antibiotic resistance.
Innovation Solution
A microfluidic circuit with a ladder-shaped network that generates a 2-fold serial dilution concentration gradient of antibiotics, allowing for rapid AST by loading a test solution into a microfluidic device, washing with oil to isolate microchambers, and detecting fluorescent signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional agar disk diffusion or broth microdilution methods are used for AST, then accuracy and reliability of results are maintained, but the testing time is excessively long (2-3 days)
Solution Approach 1:
The invention divides the AST process into multiple parallel microchamber reactions, each containing bacteria and antibiotics at different concentrations. This segmentation allows simultaneous testing of multiple antibiotic concentrations in a single device, reducing the sequential time required for traditional methods while maintaining result accuracy.
Solution Approach 2:
The invention replaces the mechanical reading process of traditional AST (visual inspection of clearing zones or turbidity after 2-3 days) with fluorescent detection. The fluorescent signal provides rapid, automated quantification of bacterial growth inhibition, enabling results to be obtained in hours rather than days without sacrificing measurement precision.
2Loss of time
If rapid AST methods are implemented to reduce testing time, then diagnostic speed improves, but accuracy and reliability of susceptibility determination may be compromised
Solution Approach 1:
The invention incorporates fluorescent detection that provides real-time feedback on bacterial growth status in each microchamber. The fluorescent signal intensity directly correlates with bacterial metabolic activity, allowing precise determination of the minimum inhibitory concentration (MIC) by identifying the lowest antibiotic concentration that completely inhibits fluorescence. This feedback mechanism ensures accurate MIC determination even with reduced incubation time.
Solution Approach 2:
The invention changes the detection parameter from visual inspection of physical changes (clearing zones, turbidity) to quantitative fluorescent signal measurement. This parameter change enables more sensitive and precise detection of bacterial growth inhibition, improving MIC determination accuracy while allowing for shorter testing durations.
3Productivity
If multiple antibiotic concentrations are tested simultaneously to improve productivity, then diagnostic throughput increases, but device complexity increases
Solution Approach 1:
The invention uses a hierarchical microchamber structure where microchambers are arranged in arrays within the microfluidic device. Each microchamber is a self-contained reaction unit that can be independently filled with bacteria and exposed to different antibiotic concentrations through the microfluidic network. This nested arrangement allows high-throughput testing while maintaining relatively simple individual chamber designs.
Solution Approach 2:
The microfluidic circuit is designed with universal components that can handle multiple antibiotic concentrations and different bacterial samples. The same microchamber array and detection system can be used for various AST applications by simply changing the antibiotic solutions loaded into the device, reducing the need for multiple specialized devices and lowering overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The microfluidic platform enables AST to be completed in less than 5 hours, maintaining accuracy and relevance with current national and international interpretive standards, thus facilitating more targeted antibiotic use.
Implementation Method 1
a microfluidic circuit with a ladder-shaped network that generates a 2-fold serial dilution concentration gradient of antibiotics
Implementation Method 2
detecting fluorescent signals
Data Source
AI summary
The present disclosure relates to a microfluidic circuit comprising a drug inlet port; an outlet port; a drug inlet main channel fluidically connecting the drug inlet port and the outlet port, where said drug inlet main channel comprises (i) a plurality of serpentine mixers and (ii) a plurality of dead-end first microchamber sets; a negative inlet port; a negative inlet main channel fluidically connecting the negative inlet port and the drug inlet main channel; a plurality (n) of ladder channels, where each of the plurality (n) of the ladder channels is fluidically connected to both the drug inlet main channel and the negative inlet main channel; and an outlet channel fluidically connected to the drug inlet main channel between the drug inlet port and the outlet port. Also disclosed is a microfluidic device comprising a microfluidic circuit of the present disclosure and a method for performing an assay.