Microfluidic Bacteria Sensor Using Ag+ Loss for Rapid Urine Counts
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Solution Overview
Problem
Current methods for quantifying bacteria in biofluids, particularly in urine samples for urinary tract infection (UTI) diagnosis, are time-consuming and require specialized facilities and trained personnel, and existing dipsticks lack accuracy and specificity, often producing false positives due to interference from medications.
Innovation Solution
A microfluidic device with a 3D-printed structure and an ion-selective electrode sensor using a polymeric coating with an ionophore to bind target ions, allowing for rapid and selective bacteria quantification by capturing bacteria on a filter membrane, rinsing, and measuring voltage loss of antibacterial ions like Ag+, eliminating chloride ion interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional plating methods are used to quantify bacteria, then accurate bacteria count can be obtained, but the process is time-consuming and requires specialized facilities and trained personnel
Solution Approach 1:
The patent replaces the mechanical/manual plating and counting process with an automated microfluidic system that uses electrochemical sensing. The microfluidic device automates sample processing, bacterial capture, and quantification through voltage measurement, eliminating the need for manual plating and visual colony counting, thus reducing detection time while maintaining accuracy.
Solution Approach 2:
The patent changes the detection parameter from visual colony counting to electrochemical voltage measurement. By measuring the voltage loss of target ions (such as silver ions) in the presence of bacteria, the system achieves rapid quantification without requiring the time-consuming culture and counting process, thereby reducing detection time while preserving measurement precision.
2Ease of operation
If dipsticks are used for urine analysis, then the process is simple and quick, but they lack accuracy and produce false positives due to interference from medications
Solution Approach 1:
The patent extracts and removes interfering substances (such as chloride ions and medication components) from the urine sample before detection. The microfluidic device incorporates filtration and separation steps that isolate the target bacteria and eliminate substances that would cause false positives, thereby maintaining ease of operation while improving measurement precision.
Solution Approach 2:
The patent introduces an intermediary substance (target ion such as silver ion) that specifically interacts with bacteria without being affected by interfering medications. The ion-selective electrode detects the voltage change caused by this intermediary-bacteria interaction, enabling accurate bacteria quantification while avoiding false positives from medication interference.
3Reliability
If selective bacteria detection is implemented, then false positives are reduced, but the device complexity increases
Solution Approach 1:
The patent designs a multi-functional microfluidic device that integrates sample introduction, filtration, bacterial capture, rinsing, and electrochemical detection into a single platform. This universal device performs multiple functions using a unified structure, reducing overall device complexity while maintaining high detection selectivity and reliability.
Solution Approach 2:
The patent employs a nested structure where the microfluidic channels are integrated within a compact housing, and the ion-selective electrode is positioned within the microfluidic chamber. This nested arrangement consolidates multiple components into a compact form, reducing device complexity while preserving the selective detection capability.
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 device provides rapid, accurate, and user-friendly UTI detection with a limit of detection as low as 70 CFU/mL, eliminating the need for centrifugation and time-consuming culture methods, and reducing false positives.
Implementation Method 1
the electrode sensor comprises a substrate having a polymeric coating comprising an ionophore that binds a target ion to be sensed
Implementation Method 2
capturing bacteria from the biofluid sample on a filter membrane positioned in a microfluidic device
Implementation Method 3
detecting a voltage loss of the target ion
Data Source
AI summary
A microfluidic device and method of using same, wherein the microfluidic device can trap bacteria from a biofluid, e.g., urine, and a silver ion selective electrode sensor can detect the loss of Ag+ in the microfluidic device because of the trapped bacteria. By knowing the loss of Ag+, the number of bacteria present in the biofluid can be accurately determined.