Microfluidic Disc Flow Splitting for Biochemical Testing
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Solution Overview
Problem
Conventional biochemical testing methods, such as sandwich ELISA, are time-consuming and labor-intensive due to the need for multiple reagent injections and manual handling, with existing microfluidic disc platforms facing issues with rotational speed control and reagent sequencing, leading to potential errors and increased costs.
Innovation Solution
A disc flow splitting test system using a rotator platform with a microfluidic disc featuring parallel splitting chambers and flow-resistant elements, which utilizes centrifugal force to evenly distribute reagents across multiple channels, reducing the need for multiple injections and stabilizing the flow to prevent contamination and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sandwich ELISA procedures are used with manual reagent loading, then the testing can be completed with standard equipment, but the process takes much time and requires repeated manual injections of reagents
Solution Approach 1:
The microfluidic disc is segmented into multiple independent microfluidic channels, each containing reservoirs for different reagents. This segmentation allows parallel processing of multiple samples simultaneously, dramatically increasing throughput while reducing the time required for manual reagent loading and handling.
Solution Approach 2:
Reagents are pre-loaded into reservoirs on the microfluidic disc before the testing process begins. This preliminary action eliminates the need for repeated manual injections during the assay, reducing both time loss and potential contamination from multiple handling steps.
2Extent of automation
If microfluidic valves are used to control reagent release at different rotational speeds, then automated reagent delivery is achieved, but the burst rotational speed varies by ±20% making sequential release unreliable
Solution Approach 1:
Each microfluidic channel is designed with locally optimized capillary structures and valve geometries that create distinct capillary pressure thresholds. This local quality differentiation ensures that each valve opens at a specific rotational speed range, maintaining reliable sequential release despite the ±20% variation in burst rotational speed.
Solution Approach 2:
The invention changes the control parameter from relying on precise rotational speed thresholds to utilizing capillary pressure differentials created by centrifugal force. By designing microfluidic channels with specific capillary dimensions and hydrophobic/hydrophilic patterns, the system achieves reliable reagent release sequencing based on gradual parameter changes rather than abrupt threshold crossings.
3Productivity
If multiple microfluidic channels are placed on one disc to increase capacity, then more samples can be tested, but the number of reagent injections increases proportionally
Solution Approach 1:
The microfluidic disc design allows a single reagent reservoir to serve multiple microfluidic channels simultaneously. Reagents are delivered once to a common reservoir and then distributed through capillary action to multiple channels, making the reagent delivery system universal across all channels rather than requiring separate delivery mechanisms for each.
Solution Approach 2:
The system utilizes capillary hydraulic principles to automatically distribute reagents from a single reservoir to multiple microfluidic channels. The capillary pressure gradient drives reagent flow through the microfluidic network without requiring active pumping or multiple injection operations, reducing device complexity while maintaining high sample throughput.
4Reliability
If ferrowax microvalves with laser irradiation are used to control reagent release, then precise sequential release is achieved, but the manufacturing difficulty increases and equipment cost rises
Solution Approach 1:
The invention replaces expensive, complex ferrowax microvalves requiring laser irradiation equipment with simple, disposable microfluidic channels made from inexpensive materials like PDMS or thermoplastics. These channels use passive capillary-based flow control that can be manufactured using standard microfabrication techniques, dramatically reducing both manufacturing complexity and equipment costs while maintaining sufficient reliability for the application.
Solution Approach 2:
The microfluidic channels are designed to be self-regulating through inherent capillary pressure differences and hydrophobic/hydrophilic surface properties. The channels automatically control reagent release timing based on rotational speed without requiring external laser irradiation or complex actuation mechanisms, making the system easier to manufacture and operate.
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 approach significantly reduces reagent injection times, enhances the accuracy of reagent sequencing, and decreases the overall time and labor required for biochemical tests, while maintaining the advantages of existing CD_ELISA methods, such as reduced reagent volume and increased reaction surface area.
Implementation Method 1
When the microfluidic disc rotates at a low speed, the liquid from the reservoirs to the entrance of the microfluidic valves will form a liquid-gas interface, and the pressure inside the liquid is also formed by centrifugation
Implementation Method 2
a capillary pressure obstructing the liquid from proceeding is generated by the surface tension on the liquid-gas interface
Implementation Method 3
Use low melting-point wax to block the microvalves so that the reagents cannot burst the ferrowax microvalves but stay in the reservoirs. As the liquid should be released, laser will be applied to melt the wax to open the microvalves and release the liquid in sequence
Data Source
AI summary
The invention provides an apparatus and methodology to carry out biochemical testing on a centrifugal platform using flow splitting technique. In conventional biochemical testing, reagents need to be loaded individually into each reservoir. By using the flow splitting technique in this invention, one reagent only need to be loaded once, then, it can be evenly distributed into each reaction chambers in single or multiple layers format. The invention greatly reduces the required manpower when large numbers of assays are integrated on one platform. Because of the invention, many medical examinations can be performed efficiently, thus reduce the waste of manpower, time and cost.