Platelet Testing Chip Using Segmented Microchannels and Stirrers
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Solution Overview
Problem
Current platelet function tests are challenging due to standardization issues, high clinical uselessness, invasive methods, and dependency on von Willebrand factor (vWF) function, which affects results and increases costs, especially when testing for anti-platelet drug effects.
Innovation Solution
A platelet-testing chip with microchannels, stirrers, and microbeads coated with reagents that induce platelet activation and aggregation, allowing for controlled shear forces and independent flow paths to measure platelet characteristics independently of blood viscosity and vWF function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long capillary is used to enable blood to flow at high shear rate for vWF activation, then platelet aggregation can be measured, but a large amount of blood is required and the test shows poor repeatability
Solution Approach 1:
The long capillary is divided into multiple short capillaries arranged in series. Each short capillary has an inner diameter of 50-150 μm and length of 1-5 mm, with 10-100 capillaries connected in series. This segmentation achieves the required high shear rate exposure (total length 10-500 mm) while using minimal blood volume (1-10 μL per capillary) and improving repeatability by ensuring uniform flow distribution across parallel paths.
Solution Approach 2:
The design transitions from a single long capillary (one-dimensional) to multiple short capillaries arranged in a two-dimensional array with parallel flow paths. This dimensional change allows simultaneous exposure of blood to high shear rates across multiple capillaries, reducing the total blood volume required while maintaining the cumulative shear rate exposure needed for vWF activation.
2Measurement precision
If a long capillary is used for high shear rate flow, then vWF activation occurs, but the vWF at the center of the tube is not activated due to minimum shear rate, causing poor repeatability
Solution Approach 1:
The single long capillary is segmented into multiple short capillaries (10-100 units) with inner diameters of 50-150 μm. This segmentation ensures that the blood flow is distributed across multiple narrow paths, creating high shear rates throughout the entire blood column in each capillary, thereby activating vWF uniformly regardless of position within the capillary.
Solution Approach 2:
The system uses controlled blood flow dynamics through the multiple short capillaries to ensure that the shear rate remains high and relatively uniform across the flow cross-section. The short length (1-5 mm) and narrow diameter (50-150 μm) of each capillary create conditions where the entire blood volume experiences sufficient shear stress for vWF activation, eliminating the gradient problem in long capillaries.
3Measurement precision
If conventional platelet function tests are used, then platelet aggregation can be measured, but the tests are dependent on vWF function and hematocrit, increasing testing costs
Solution Approach 1:
The patent applies local quality by creating specific flow conditions (high shear rate) in localized regions (short capillaries with 50-150 μm inner diameter) that are optimized for vWF activation and platelet aggregation. The microchannel design ensures that platelet-rich regions experience the necessary shear stress independently of overall blood viscosity and hematocrit variations, allowing accurate platelet function measurement across different blood conditions.
Solution Approach 2:
The invention changes the flow parameters by using multiple short capillaries with specific dimensions (50-150 μm inner diameter, 1-5 mm length) arranged in series, creating high shear rates (1000-5000 s⁻¹) that are maintained consistently regardless of blood viscosity or hematocrit. This parameter control allows the test to measure platelet aggregation independently of vWF function and blood composition variations.
4Measurement precision
If a two-stage test process is used for platelet function testing, then comprehensive platelet function can be assessed, but testing costs increase
Solution Approach 1:
The patent merges multiple test functions into a single integrated microchip device. The chip simultaneously performs vWF-dependent platelet aggregation testing and vWF-independent platelet function testing using multiple short capillaries with different coatings (collagen/ADP in some capillaries, collagen only in others). This allows comprehensive platelet function assessment in a single test run, eliminating the need for sequential two-stage testing and reducing both time and cost.
Solution Approach 2:
The microchip device is designed with multi-functionality, incorporating multiple short capillaries that can be coated with different reagents (collagen, ADP, epinephrine) to perform various platelet function tests simultaneously. The same device can assess vWF-dependent aggregation, vWF-independent aggregation, and drug resistance, providing universal platelet function evaluation without requiring separate testing equipment or procedures.
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
This solution enables accurate and cost-effective measurement of platelet characteristics by eliminating measurement errors caused by blood viscosity and vWF, allowing for a single test to assess platelet function and drug reactions, reducing test time and costs.
Implementation Method 1
an stirrer provided in the sample storage chamber to induce a shear flow in the blood sample
Implementation Method 2
microbeads which are received in one or more of the plurality of the sample chambers and which are coated with a reagent for activating platelets on an outer surface thereof
Data Source
AI summary
Disclosed is a platelet-testing chip. The platelet-testing chip includes a plurality of sample chambers storing blood samples, stirrers provided in the sample chambers to apply shearing force to the blood samples, a plurality of waste sample chambers provided so as to correspond to the plurality of the sample chambers, microchannels, through which the sample chambers and the waste sample chambers corresponding to each other are independently connected to thus form paths through which the blood samples flow from the sample chambers to the corresponding waste sample chambers, and microbeads which are received in one or more of the plurality of the sample chambers and which are coated with a reagent for activating platelets on an outer surface thereof. When the blood samples are transferred from the sample chambers through the microchannels, the microbeads are transferred together with the blood samples.