Diagnostic Device Flow Control for COVID-19 Antibody Detection
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Solution Overview
Problem
Current diagnostic tests for COVID-19, particularly antigen tests and serology tests, face challenges in reliability and sensitivity, especially with lateral flow immunoassay tests being prone to variability and false positives due to design limitations and cross-reactivity issues, and ELISA tests requiring skilled personnel and lengthy processing times.
Innovation Solution
Incorporating a flow control structure between the nitrocellulose membrane and the casing of the QuickCard test to control liquid flow, focusing on detecting antibodies against the COVID-19 spike protein, specifically the S1 spike protein, and providing multiple antigen versions to reduce false positives, while ensuring all biological sample contacts the detection area for maximum effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If lateral flow immunoassay tests are used for COVID-19 detection, then the tests are suited for domestic use and easy operation, but the accuracy and reliability (sensitivity and specificity) are questionable due to design limitations and component detachment
Solution Approach 1:
The test device is divided into functionally independent components: a test strip with integrated detection elements and a separate control mechanism. This segmentation allows the test strip to maintain structural integrity while the control mechanism independently manages component positioning and prevention of detachment, resolving the contradiction between ease of operation and reliability.
Solution Approach 2:
An intermediary control mechanism is introduced between the user and the test strip components. This intermediary system (including positioning structures and bonding mechanisms) ensures components remain in correct positions during operation while maintaining the simplicity of the overall device for domestic use, thereby improving reliability without sacrificing ease of operation.
2Adaptability or versatility
If lateral flow immunoassay tests are used, then the tests can be performed by non-medical practitioners, but the sensitivity and specificity for detecting COVID-19 virus are questionable due to limited sample volume and design limitations
Solution Approach 1:
The test strip structure is extended in multiple dimensions with integrated sampling wells, capillary channels, and detection zones arranged in a multi-dimensional configuration. This dimensional expansion increases the effective sample volume interaction area while maintaining the simplicity of the device for non-medical users, thereby improving measurement precision without reducing adaptability.
Solution Approach 2:
Multiple functional elements are nested within the test strip structure: sampling wells are integrated into the strip, capillary channels are embedded within the matrix, and detection elements are incorporated into the same structure. This nesting maximizes the utilization of limited sample volume while maintaining device simplicity for versatile use by non-medical practitioners.
3Reliability
If ELISA tests are used for COVID-19 antibody detection, then the tests provide reliable detection, but the tests must be performed in equipped laboratories with skilled staff and take 1 to 5 hours to give results
Solution Approach 1:
The manual, time-consuming ELISA procedure is replaced with an automated lateral flow immunoassay system that uses capillary action and integrated detection mechanisms. This substitution eliminates the need for skilled laboratory staff and equipped facilities while reducing the testing time from 1-5 hours to approximately 20 minutes, maintaining reliability through standardized detection protocols.
Solution Approach 2:
The test device is designed to perform all necessary functions autonomously: sample application, fluid transport through capillary channels, antigen-antibody binding, and visual detection are all self-executing without requiring skilled intervention. This self-service capability maintains the reliability of detection while dramatically reducing the time and expertise required compared to traditional ELISA tests.
4Measurement precision
If multiple antigen versions are provided to reduce false positives, then the detection accuracy improves, but the device complexity increases
Solution Approach 1:
Multiple antigen versions are merged into a single integrated test strip structure, with different antigens positioned at distinct locations along the capillary channel. This merging approach allows simultaneous detection of multiple viral proteins (such as spike protein and nucleocapsid protein) in a single test, improving measurement precision while minimizing the increase in device complexity through unified integration.
Solution Approach 2:
Different regions of the test strip are assigned different antigen compositions tailored to detect specific viral proteins. Each local zone has optimized antigen characteristics (such as spike protein in one region and nucleocapsid protein in another) to provide targeted detection, improving precision without requiring complete redesign of the entire device structure.
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 solution enhances the reproducibility and reliability of the test, reduces false positives, and allows for accurate detection of COVID-19 antibodies, even with low sample volumes, providing a more efficient and reliable diagnostic tool for COVID-19 detection.
Implementation Method 1
a nitrocellulose membrane located so as to cover the aperture and being supported on a liquid-absorbent pad
Implementation Method 2
a liquid-absorbent pad... Excess liquid from the sample is then absorbed through the nitrocellulose membrane and into the liquid-absorbent pad
Data Source
AI summary
A diagnostic device (1) for detecting a first member of a reporter-analyte pair. The diagnostic device comprises an inlet for receiving a liquid, biological sample and a porous membrane element (10) comprising a detection portion. The detection portion is in liquid communication with the inlet and a second member of the reporter-analyte pair is immobilised on the detection portion. One of the first or second member of the reporter-analyte pair comprises a biological antigen and the other of the first or second member of the reporter-analyte pair comprises an antibody specific for the biological antigen. The biological antigen comprises a spike protein, or a fragment thereof, of COVID-19. The device is for independent detection of the spike protein, or the fragment thereof, or of an antibody specific for the spike protein, or the fragment thereof, in the biological sample.