Optofluidic Bacterial Cell Counting via Filter Strip Staining
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Solution Overview
Problem
Current bacterial detection methods are time-consuming, require lab facilities and trained personnel, and are not suitable for real-time, on-site monitoring, especially in environments where enzyme activity is temperature-sensitive and non-specific to bacteria.
Innovation Solution
An automated bacterial cell counting device using an optofluidic chip with a filter strip and nanoparticle reagents for continuous detection, capable of measuring colorimetric and fluorescence outputs to quantify bacterial cells without the need for culture or enzyme-based methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If plate culture method is used for bacterial detection, then detection accuracy is improved, but detection time increases significantly (2-7 days)
Solution Approach 1:
The invention extracts the bacterial cells from the liquid sample using a filter strip, separating them from the bulk liquid medium. This extraction enables subsequent rapid staining and detection without requiring prolonged culture periods, thus reducing detection time while maintaining accuracy
Solution Approach 2:
The invention employs colorimetric staining where bacterial cells accumulate stain and change color intensity proportional to their concentration. This color change provides a rapid visual and instrumental readout that eliminates the need for time-consuming culture growth, achieving both speed and accuracy
2Loss of time
If enzymatic methods are used for bacterial detection, then detection time is reduced (18-44 h), but specificity to bacteria decreases and lab facility dependence increases
Solution Approach 1:
The invention replaces enzyme-based biochemical detection with a physical staining mechanism using membrane-permeable dyes. Bacterial cells take up stain based on their membrane integrity and cellular structure, providing a more specific and reliable indication of viable bacterial cells without the limitations of enzyme activity measurements
Solution Approach 2:
The invention uses disposable filter strips with integrated staining reagents that are discarded after single use. This eliminates the need for expensive, complex enzymatic reaction systems and laboratory facilities, making the test portable and suitable for field use while maintaining reliability
3Loss of time
If molecular methods like PCR are used for bacterial detection, then detection speed is improved, but device complexity and requirement for trained personnel increase
Solution Approach 1:
The invention extracts and concentrates bacterial cells onto a filter strip membrane, physically separating them from the sample matrix. This simple extraction step replaces complex molecular extraction and purification steps required for PCR, reducing device complexity while enabling rapid detection
Solution Approach 2:
The invention creates a visual copy of bacterial presence through colorimetric staining on the filter strip. The stained bacterial cells serve as a direct visual indicator that can be read without complex instrumentation, replacing the need for sophisticated PCR equipment and expert interpretation
4Productivity
If automated sequential processing is implemented, then productivity is improved, but device complexity increases
Solution Approach 1:
The invention merges multiple functions (filtering, staining, washing, and detection) into a single integrated filter strip cartridge. This consolidation allows automated sequential processing to be implemented without proportionally increasing system complexity, as all reagents and structures are pre-integrated in one disposable unit
Solution Approach 2:
The filter strip serves multiple functions simultaneously: it filters bacterial cells from liquid, provides a support matrix for staining reagents, enables washing steps, and serves as the detection substrate. This multi-functionality increases productivity without requiring separate devices for each step
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
Enables rapid, automated, and accurate bacterial cell counting with a limit of detection of 1000 CFU/mL, suitable for real-time monitoring in various environments, including remote sites, and can detect multiple bacteria species with programmable nanoreagent cartridges.
Implementation Method 1
a filter strip passing through the optofluidic chip and in fluid communication with the cartridge and the inlet, the filter strip for trapping or retaining bacterial cells on its surface
Implementation Method 2
the optofluidic chip is capable of detecting a colorimetric and/or fluorescence output emitted from the bacterial cells modified by the reagents
Implementation Method 3
the optofluidic chip is capable of detecting a colorimetric and/or fluorescence output emitted from the bacterial cells modified by the reagents
Data Source
AI summary
The disclosure concerns bacterial cell counting devices, systems and methods thereof. The bacterial cell counting device comprises at least one cartridge for containing reagents; an inlet for introducing a sample containing bacterial cells into the device; an optofluidic chip separately in fluid communication with the cartridge and the inlet; a filter strip passing through the optofluidic chip and in fluid communication with the cartridge and the inlet, the filter strip for trapping or retaining bacterial cells on its surface such that the bacterial cells can interact with the reagents as they flow through the filter strip; and a controller for controlling a sequential flow of reagents and sample to the filter strip via the optofluidic chip. The optofluidic chip is capable of detecting a colorimetric and/or fluorescence output emitted from the bacterial cells modified by the reagents in order for the bacterial cells to be quantified relative to a control.