Microfluidic Test Strip with Retention Valve for Saliva Assays
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Solution Overview
Problem
Existing methods for salivary hormone testing are complex, require multiple reagents and sample pre-treatment, and are unsuitable for home use due to the need for lab environments and trained professionals, making them inconvenient and prone to errors.
Innovation Solution
An integrated fluid sample test strip with an inlet for retaining solutions, a reaction chamber with bioreceptors, a capillary pump with vent holes to reduce pressure, and a test chamber with electrochemical electrodes for sensitive analyte detection, allowing for accurate and reliable measurements in a compact, portable device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing ELISA methods are used for salivary hormone testing, then sensitivity and measurement precision are improved, but device complexity and ease of operation deteriorate due to requiring multiple reagents, sample pre-treatment, and lab environment
Solution Approach 1:
The patent combines multiple testing functions (sample reception, retention valve control, reaction chamber mixing, capillary pump fluid transport, and test chamber detection) into a single integrated test strip device. This merging eliminates the need for separate laboratory equipment and multiple reagent handling steps, resolving the contradiction between maintaining measurement precision and reducing device complexity.
Solution Approach 2:
The test strip employs passive capillary action for fluid transport through the device, automatic retention valve operation based on fluid presence, and integrated bioreceptor-coated surfaces that eliminate separate sample preparation steps. The system serves itself by using the sample fluid's own properties to drive the testing process, reducing the need for complex external control mechanisms.
2Measurement precision
If existing ELISA methods are used for salivary hormone testing, then measurement precision is improved, but ease of operation deteriorates due to requiring trained professionals and lab environment
Solution Approach 1:
The retention valve automatically opens or closes based on the presence or absence of fluid in the inlet, eliminating the need for manual valve control by the user. The capillary pump automatically transports fluids through the device using capillary action, requiring no user intervention. This self-service mechanism allows untrained users to operate the device simply by adding their sample.
Solution Approach 2:
The patent replaces manual mechanical operations (such as centrifugation, pH adjustment, and manual fluid transfer) with passive physical-chemical mechanisms. The retention valve uses surface tension and contact angle changes rather than mechanical actuators, and the capillary pump uses capillary pressure rather than mechanical pumping, making the device easy to operate without specialized training.
3Reliability
If existing methods are used for salivary hormone testing, then reliability is improved through controlled sample preparation, but device complexity and ease of operation worsen due to requiring multiple reagents and pre-treatment steps
Solution Approach 1:
The patent merges the reaction chamber and test chamber into a single integrated microfluidic pathway within the test strip. The bioreceptors are pre-coated on the test chamber surface during manufacturing, eliminating the need for users to handle multiple reagents. This integration maintains reliable quantitative results by controlling the reaction environment while reducing the number of user-managed components.
Solution Approach 2:
The bioreceptors are pre-attached to the test chamber surface during device manufacturing, and the retention valve is pre-configured with specific contact angles for automatic operation. This preliminary preparation of critical components during fabrication ensures reliable and reproducible results without requiring users to perform complex sample pre-treatment or reagent preparation steps.
4Ease of operation
If compact and portable test apparatus is developed, then ease of operation and accessibility are improved, but measurement precision and sensitivity deteriorate due to reduced device size
Solution Approach 1:
The patent uses capillary pressure (a hydraulic principle) to automatically transport small volumes of fluid through the microfluidic channels of the compact test strip. The retention valve utilizes surface tension and contact angle changes to control fluid flow without mechanical components. These hydraulic and pneumatic principles enable precise control of minute fluid volumes in a compact format, maintaining measurement precision while achieving portability.
Solution Approach 2:
The test strip incorporates porous materials in the capillary pump and retention valve structures to enable controlled fluid transport and retention through capillary action. The porous structure provides large surface area for fluid interaction within a small volume, maintaining sensitive detection capability while enabling a compact, portable device design suitable for home use.
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 precise and sensitive detection of analytes in saliva without the need for lab settings or extensive user intervention, providing accurate and reliable results in a short time, suitable for point-of-care applications.
Implementation Method 1
the inlet comprises a retention valve for temporarily retaining each said solution to thereby reduce air flow through the retention valve
Implementation Method 2
a capillary pump for receiving from the reaction chamber at least one of the solutions including at least the fluid sample, the capillary pump comprising at least one vent hole to allow any air to escape from the capillary pump and thereby reduce pressure in the capillary pump
Implementation Method 3
a hydrophobic vent hole coupled to the test chamber to allow a flow of solution from the reaction chamber into the test chamber when the vent hole is unsealed
Implementation Method 4
the test chamber to receive the substrate solution from the reaction chamber, the test chamber comprising a plurality of test electrodes to perform at least part of a biosensing test of the substrate solution
Implementation Method 5
a test chamber with electrochemical electrodes for sensitive analyte detection, allowing for accurate and reliable measurements
Data Source
AI summary
The disclosure describes an integrated fluid sample test strip comprising: an inlet for receiving solutions comprising a fluid sample and a substrate solution, the inlet comprising a retention valve for temporarily retaining each solution to thereby reduce air flow through the valve; a reaction chamber to receive the solutions via the retention valve, the chamber functionalized with bioreceptor(s); a capillary pump to receive from the reaction chamber the solution(s), the pump comprising vent hole(s); a test chamber to receive the substrate solution from the reaction chamber, the test chamber comprising test electrodes for a biosensing test of the substrate solution; a hydrophobic vent hole coupled to the test chamber to allow a flow of solution from the reaction chamber into the test chamber when the vent hole is unsealed and to allow a flow of solution from the reaction chamber to the capillary pump when the vent hole is sealed.