Capillary Microfluidic Loading for Immunoassay Accuracy
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Solution Overview
Problem
Existing blood sample analysis systems face inefficiencies due to inhomogeneous pressure distribution, suction issues in sample retainers, and leakage problems in smaller channels, leading to inaccurate results and inefficient unloading processes, particularly in pump-based systems and paper-based lateral flow assays.
Innovation Solution
A microfluidic apparatus and process utilizing capillary action to load and unload fluids into microchannels, enabling precise control and automation of fluid mixing and analysis, including enzyme-linked immunosorbent assays, with a sequential loading and unloading unit, signal detection, and output device for generating analysis messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pump-based systems are used for fluid delivery, then fluid can be moved through channels, but pressure distribution becomes inhomogeneous causing weak spots and suction issues
Solution Approach 1:
The patent replaces pump-based mechanical systems with capillary action-driven microfluidic systems. The microchannels are designed with specific dimensions and surface properties that enable capillary forces to drive fluid flow without mechanical pumps, eliminating pressure distribution issues while maintaining reliable fluid delivery.
Solution Approach 2:
The patent uses capillary pressure (a hydraulic principle) to drive fluid flow through microchannels. By designing channels with appropriate diameter and surface tension characteristics, the system generates sufficient capillary pressure to move fluids reliably without mechanical pumps, achieving uniform pressure distribution throughout the system.
2Productivity
If suction forces are applied in sample retainers, then fluids can be drawn into channels, but corner regions and distant channels experience poor loading efficiency
Solution Approach 1:
The patent segments the fluid delivery system into multiple independent capillary channels, each with its own capillary-driven flow path. This segmentation ensures that each channel receives fluid independently through capillary action, eliminating the suction distribution problems that affect corner and distant channels in pump-based systems.
Solution Approach 2:
Each microchannel in the patent is designed to self-load fluid through its own capillary action. The channels automatically draw in samples and reagents without external suction forces, ensuring uniform loading efficiency across all channels including corners and distant regions, as each channel serves itself independently.
3Manufacturing precision
If channels with smaller diameter are used, then more precise control is achieved, but backpressure increases causing leakage issues
Solution Approach 1:
The patent carefully optimizes the dimensional parameters of microchannels (diameter, length, width) to achieve the desired precision while maintaining appropriate backpressure levels. By adjusting these parameters within specific ranges, the system achieves precise fluid control without excessive backpressure that would cause leakage.
Solution Approach 2:
The patent replaces mechanical pressure systems with capillary action, which naturally limits the pressure to levels determined by surface tension and channel geometry. This substitution eliminates the backpressure leakage issues associated with pump-based systems while maintaining precise channel dimensions for accurate fluid control.
4Ease of operation
If paper-based or cotton-based materials are used for unloading, then fluids can be transferred through capillary action, but the process is inefficient
Solution Approach 1:
The patent employs porous materials with optimized pore structures for unloading fluids from microchannels. These materials provide enhanced capillary action compared to conventional paper or cotton, enabling faster and more efficient fluid transfer while maintaining operational simplicity. The porous structure allows rapid wicking of fluids without sacrificing ease of 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
This approach enhances the accuracy and efficiency of microfluidic operations, reducing leakage issues and improving scalability, while providing a clear and concise diagnostic readout for biomarker concentrations, facilitating informed clinical decisions.
Implementation Method 1
guiding the predetermined substance into the microchannel by capillary action, thereby mixing the predetermined substance with the sample
Implementation Method 2
The unloading can include dipping the chip onto a porous wick or fiber pad
Data Source
AI summary
A process and an apparatus conduct microfluidic loading and unloading of fluids into microchannels for performing assays, such as immunoassays. The apparatus includes a sequential loading and unloading unit having a movable member dipping a chip having a microchannel including a sample into a cartridge retaining a substance to guide the predetermined substance into the microchannel by capillary action to mix the predetermined substance with the sample. A signal detection unit performs an analysis of the mixed sample and generates an analysis message corresponding to the sample. An output device outputs the analysis message. The process implements operation of the apparatus.