Multiplexed Immunoassay Device with Segmented Flow Paths
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Solution Overview
Problem
Current immunoassay devices for detecting COVID-19 antibodies in body fluids face challenges with sensitivity and specificity, particularly in distinguishing between IgM and IgG antibodies, and require complex migration paths for analytes and conjugate systems, which can lead to false positives and require large sample volumes.
Innovation Solution
A rapid detection immunoassay device with a dry or liquid conjugate system using separate sorbent materials with distinct flow paths and test zones, allowing for simultaneous detection of COVID-19 IgM and IgG antibodies to nucleocapsid proteins, spike protein S1 subunits, and receptor binding domain antigens, without the need for analyte migration along the same path as conjugate-carrying buffer solutions, using a T-shaped configuration and immobilized antigens or antibodies in test zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single migration path is used for both analyte and conjugate, then device complexity is reduced, but measurement precision and reliability deteriorate due to false positives and cross-contamination
Solution Approach 1:
The device divides the flow path into separate channels: a first flow path for analyte migration and a second flow path for conjugate migration. These paths are physically separated to prevent cross-contamination while maintaining independent control over each reagent's delivery, thereby improving measurement precision without excessive complexity
Solution Approach 2:
A buffer solution acts as an intermediary carrier in the second flow path, transporting the conjugate to the test zone without direct contact with the analyte path. This intermediary mechanism enables precise conjugate delivery while maintaining path separation for improved reliability
2Reliability
If conventional immunoassay methods are used, then detection capability is achieved, but sensitivity and specificity worsen due to false positives and inability to distinguish IgM from IgG
Solution Approach 1:
The test zone contains multiple test lines with different immobilized antigens that specifically bind to different antibody types (IgM and IgG). This segmentation of detection targets within the same device enables simultaneous differentiation of antibody types with high precision and reliability
Solution Approach 2:
Different regions of the test strip (different test lines) have specialized properties with specific antigens immobilized for detecting particular antibody types. This local quality differentiation allows precise identification of IgM versus IgG responses at specific locations within the device
3Measurement precision
If complex sandwich assays are used to improve sensitivity, then detection sensitivity improves, but device complexity and sample volume requirements worsen
Solution Approach 1:
The device separates conjugate delivery and analyte detection into distinct flow paths, allowing a simplified single-step assay design that achieves high sensitivity without requiring complex multi-step sandwich structures. The separation enables efficient reagent usage and reduced sample volume requirements
Solution Approach 2:
The conjugate system is designed to be universal, working across multiple test lines for different antibody types. This multi-functionality allows a single conjugate formulation to support detection of both IgM and IgG antibodies, reducing overall device complexity while maintaining high sensitivity across all detection channels
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 highly sensitive and accurate detection of multiple COVID-19 antibodies from small sample volumes, reducing false positives and enabling precise differentiation between IgM and IgG responses, facilitating effective monitoring of COVID-19 infections and vaccinations.
Implementation Method 1
a first sorbent material defining a first horizontal flow path, a second sorbent material defining a second horizontal flow path distinct from the first flow path
Implementation Method 2
test spots (e.g., lines) or test sites with immobilized antigens or antibodies or other ligand binding molecules such as aptamers, nucleic acids, etc. located in a test zone
Data Source
AI summary
Test cells with first and second sorbent materials defining a first flow path for a solution, a second flow path distinct from the first flow path for a sample, and a test site with immobilized antigens or antibodies or other ligand-binding molecules located at the junction of the sorbent materials for identifying one or more ligands. In one embodiment, a single highly sensitive immunoassay device is provided that detects the presence in a body fluid sample of two or more COVID-19 (Coronavirus disease 2019) antibodies including immunoglobulin M (IgM) and/or immunoglobulin G (IgG) antibodies to nucleocapsid protein (NP) and spike protein receptor binding domain (RBD), and optionally spike protein S1 subunit (S1) COVID-19 virus antigens. The immunoassay device is sensitive in detecting early infection using IgM antibody detection and continuing infection using IgG antibody detection. Additionally, successful inoculation is distinguished from infection after inoculation by comparing NP and RBD results.