Lateral Flow Assay Backflow Inhibition via Hydrophobic Barrier
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Solution Overview
Problem
Existing rapid chemical tests for fluids, such as dip-and-read test strips, are not suitable for modern immunoassay devices and require direct contact with samples, posing a risk of contamination for operators and samples.
Innovation Solution
Lateral flow test strips with a bibulous material, filter member, and reagent pad that inhibit backflow, allowing for capillary transport and detection of physical properties like pH and adulterants in liquid samples without direct operator contact, using a hydrophobic member to prevent reagent movement and a cover to protect components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dip-and-read test strips are used for chemical analysis, then the operator can perform tests, but the operator must open the device and expose themselves to contamination with the sample and the sample to contamination by the operator or by other reagents on the test strip
Solution Approach 1:
The test device is divided into separate functional zones: a sample introduction zone, a lateral flow path with multiple reagent pads, and a result reading zone. This segmentation allows the sample to flow through dedicated channels without requiring operator contact with reagents, thereby reducing contamination risk while maintaining ease of operation.
Solution Approach 2:
A lateral flow system acts as an intermediary between the sample introduction and the reagent pads. The sample flows laterally through a controlled path to reach multiple reagent pads sequentially, eliminating the need for the operator to directly handle the sample and reagents, thus reducing contamination while preserving test functionality.
2Adaptability or versatility
If multiple reagent pads are incorporated into a single test strip, then the device can test for multiple properties, but reagents may move between pads and obscure results
Solution Approach 1:
Each reagent pad is positioned in a distinct lateral zone with unique local properties. The test strip incorporates zone-specific reagent pads (e.g., pH pad, specific gravity pad, adulterant pad) that are spatially separated, allowing multiple tests to be performed simultaneously without cross-contamination of reagents, thus maintaining both versatility and result clarity.
Solution Approach 2:
The test strip is segmented into multiple laterally arranged reagent pads, each dedicated to a specific test. This spatial segmentation prevents reagent migration between pads and ensures that each pad produces its own distinct, unobscured result, enabling multiple properties to be tested simultaneously with clear, interpretable results.
3Reliability
If a filter member is added to inhibit backflow, then reagent movement is prevented, but the device structure becomes more complex
Solution Approach 1:
A thin film filter member is integrated into the test strip structure to prevent reagent backflow. This thin film barrier is incorporated as part of the lateral flow path, providing effective reagent isolation without adding significant structural complexity or bulk to the device, thus maintaining reliability while minimizing complexity increase.
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 safe and effective analysis of liquid samples for contamination and adulteration, reducing exposure risks and improving assay clarity by preventing backflow and allowing multiple reagent pads without obscuring results.
Implementation Method 1
The liquid sample is transported through the test strip by capillary action
Implementation Method 2
The filter member is made of a material that inhibits backflow of fluid from the reagent pad to the bibulous material
Data Source
AI summary
The present invention is directed novel lateral flow devices for analyzing liquid samples. The devices contain chemical test strips and are useful for testing liquids for physical properties, such as pH, specific gravity, contamination or adulteration, the presence of proteins or blood, and the like. The test strips contain a bibulous material, a filter element, a reagent pad, and in some embodiments also contain a hydrophobic member and a cover. Any fluid can be tested, for example, urine or other body fluids, environmental samples, biological samples, clinical samples, or food and beverage samples.