Microreactor Lateral Flow Assay for Low-Load Pathogen Detection
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Solution Overview
Problem
Existing lateral flow assays for diagnosing diseases, such as COVID-19, suffer from high variance, low sensitivity, low repeatability, and susceptibility to misinterpretation, particularly at low viral loads, due to inefficient spatiotemporal extraction and concentration of analytes and capture molecules.
Innovation Solution
A diagnostic assay device with a microreactor configured to flow a sample solution vertically through a porous wicking filter to form an analyte-capture molecule complex, followed by horizontal transfer to an absorbent strip pad, enhancing the spatial and temporal control of the reaction and increasing the concentration of analyte and capture molecules for improved sensitivity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lateral flow through absorbent strip pad is used, then device simplicity is maintained, but sensitivity and detection precision deteriorate due to spatial dilution of analytes
Solution Approach 1:
The device is divided into two functional segments: a microreactor chamber for concentration and complex formation, and an absorbent strip pad for lateral flow and detection. This segmentation allows each component to perform its optimized function - the microreactor enhances sensitivity through concentration while the strip pad maintains operational simplicity.
Solution Approach 2:
The microreactor chamber acts as an intermediary component between the sample application and the absorbent strip pad. It pre-concentrates analytes and facilitates complete complex formation before the sample reaches the strip pad, thereby improving detection sensitivity without compromising the simplicity of the overall device.
2Speed
If analytes are diluted during lateral flow, then flow through the strip pad is facilitated, but detection sensitivity deteriorates due to reduced analyte concentration
Solution Approach 1:
The microreactor performs preliminary concentration of analytes and complete complex formation before the sample enters the absorbent strip pad. This preliminary action ensures that analytes are at optimal concentration for detection, preventing the sensitivity loss that would normally occur during lateral flow dilution.
Solution Approach 2:
The device transitions from a single-dimensional lateral flow process to a two-dimensional process by adding the vertical microreactor chamber. Sample flow occurs vertically through the microreactor for concentration, then laterally through the strip pad for detection, allowing concentration enhancement without compromising flow facilitation.
3Ease of manufacture
If capture molecules are dispersed in the strip pad, then device manufacturing is simplified, but reaction efficiency deteriorates due to reduced spatial overlap with analytes
Solution Approach 1:
Capture molecules are segregated into two locations: concentrated in the microreactor chamber for high-efficiency binding, and present on the absorbent strip pad for detection. This segmentation enables both efficient reaction in the microreactor and simplified manufacturing of the strip pad component.
Solution Approach 2:
The microreactor chamber provides a localized region of high capture molecule concentration optimized for reaction efficiency, while the absorbent strip pad maintains a simpler, more dispersed distribution suitable for manufacturing and detection functions.
4Reliability
If sample analysis time is extended for complete reaction, then reaction completeness is improved, but productivity deteriorates due to slower throughput
Solution Approach 1:
The microreactor modifies the physical parameters of the reaction environment - increasing capture molecule concentration and optimizing flow dynamics - to accelerate the reaction rate. This allows complete complex formation to occur rapidly, achieving both reaction completeness and high throughput.
Solution Approach 2:
The device employs controlled periodic flow through the microreactor, allowing multiple passes of sample over the capture molecules. This periodic action ensures complete reaction while maintaining rapid overall processing time, thereby achieving both reliability and productivity.
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 significantly enhances sensitivity and reduces false negatives by ensuring high concentrations of analyte and capture molecules are in close proximity, forming complexes efficiently and quickly, while using small sample volumes, and allows for rapid, accurate detection of analytes like SARS-CoV-2, RSV, and influenza antigens.
Implementation Method 1
A diagnostic assay device featuring a microreactor with a porous wicking filter that concentrates analytes and capture molecules in close proximity
Implementation Method 2
The absorbent strip pad is configured to flow therethrough, in a second direction crossing the first direction, the sample solution including the analyte-capture molecule complex formed in the microreactor and indicate a presence of the analyte-capture molecule complex
Data Source
AI summary
Diagnostic assay devices for detecting the presence of an analyte in a sample solution may comprise a microreactor configured to form a sample solution containing the analyte, flow the sample solution therethrough in a first direction to form an analyte-capture molecule complex, and transfer the sample solution to an absorbent strip pad configured to flow therethrough, in a second direction crossing the first direction, the sample solution including the analyte-capture molecule complex and indicate a presence of the analyte-capture molecule complex. The diagnostic devices may be used, for example, to identify the presence of SARS-Cov2, RSV, influenza A, influenza B or other pathogens in samples from patients.