Capacitive Lateral Flow Test Strip for Quantitative Analysis
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Solution Overview
Problem
Conventional lateral flow tests rely on subjective visual inspection, which can lead to false-negative or false-positive results, and lack the capability to quantify analyte concentration accurately, necessitating the development of a more objective and quantitative measurement system.
Innovation Solution
A lateral flow test arrangement incorporating a test strip with sensing and reference capacitors, where electrodes are aligned with the test line and control line, and an electronic circuit measures time-dependent capacitance differences to determine analyte concentration and flow rate, enabling objective and quantitative analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection is used to read lateral flow test results, then the device complexity is low, but the measurement precision and reliability are reduced due to subjectivity
Solution Approach 1:
The patent replaces the mechanical/visual inspection system with an electrical measurement system. Capacitive sensors detect marker accumulation at test lines by measuring changes in electrical capacitance, eliminating subjective visual interpretation and significantly improving measurement precision and reliability of lateral flow test results
Solution Approach 2:
The capacitive sensing system provides multiple functions: it can detect various analytes by placing sensors at different test line locations, enable quantitative measurement of analyte concentration through capacitance magnitude, and determine flow rate through temporal analysis, replacing multiple separate functions with a single sensing mechanism
2Measurement precision
If optical systems with LEDs and photodiodes are used to replace visual inspection, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent substitutes the optical measurement system (LEDs and photodiodes) with an electrical capacitive sensing system. This replacement maintains the ability to detect marker accumulation at test lines while significantly reducing device complexity, component count, and manufacturing cost compared to optical systems
Solution Approach 2:
The patent changes the detection parameter from optical properties (light absorption/reflection) to electrical properties (capacitance). This parameter change enables the use of simpler, smaller, and less expensive capacitive sensors instead of complex optical components, while still achieving accurate detection of analyte presence
3Quantity of substance
If conventional visual lateral flow tests are used, then the device complexity is low, but the ability to quantify analyte concentration is lost
Solution Approach 1:
The patent replaces visual assessment with electrical capacitive measurement to enable quantitative analysis. The capacitance signal magnitude correlates with the amount of marker accumulation, which in turn correlates with analyte concentration, providing objective quantitative data rather than subjective visual interpretation
Solution Approach 2:
The capacitive sensing system provides quantitative feedback about analyte concentration through measurable electrical signals. The system can detect and report the magnitude of capacitance changes, enabling determination of analyte concentration levels and facilitating more informed diagnostic decisions
4Adaptability or versatility
If multiple test lines are added to detect different analytes, then the versatility is improved, but the device complexity and cost increase
Solution Approach 1:
The capacitive sensing system enables a single sensor to perform multiple detection functions. By placing capacitive sensors at different test line locations on the strip, the system can detect multiple different analytes simultaneously, providing multiplexed testing capability without requiring separate detection systems for each analyte
Solution Approach 2:
The patent merges multiple detection functions into a unified capacitive sensing platform. Different test lines for different analytes are read by capacitive sensors, combining what would traditionally require multiple separate detection systems into a single integrated system, reducing overall complexity and cost
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
This solution provides a more accurate and objective measurement of analyte concentration and flow rate, reducing the subjectivity of visual inspections and enabling the detection of multiple analytes in a single test, enhancing the reliability and multiplexing capabilities of lateral flow tests.
Implementation Method 1
a sensing test capacitor having electrodes extending across the test strip at least partially aligned with the test region
Implementation Method 2
Accumulation of marker molecules in the test region then may alter the permittivity of the material directly between the electrodes—that is to say, the capacitor conductive plates—and cause a relatively larger change to the capacitance
Data Source
AI summary
A lateral test flow arrangement for a test molecule is disclosed, comprising: a test strip for transporting an analyte away from a sampling region and towards an absorbing region, the test strip having therein and remote from the sampling region, a test region for functionalization with a molecule which binds to the test molecule or to a conjugate of the test molecule; a sensing test capacitor having electrodes extending across the test strip at least partially aligned with the test region and being physically isolated therefrom; a reference test capacitor having electrodes extending across the test strip and being physically isolated therefrom; and an electronic circuit configured to measure a time-dependant capacitance difference between the sensing test capacitor and the reference test capacitor. A method for carrying out that lateral flow tests is also disclosed, as are test systems and in particular pregnancy test systems.