Microfluidic Microvalve Structure for Sequential Multi-Fluid Control
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Solution Overview
Problem
Existing microvalves in microfluidic chips face issues such as sticking, difficulty in precise fluid control, limited reusability, and inability to manage multiple fluids simultaneously, leading to contamination and increased complexity in processing and assembly, while built-in reagents pose challenges in long-term storage and miniaturization.
Innovation Solution
A microvalve design featuring non-communicating flow guide channels and a piston principle, allowing sequential release of liquids and enabling multiple fluid control with a simple structure, facilitating easy assembly and reusability, and long-term reagent sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional microvalve with a deformable film and valve seat is used, then the flow channel can be opened and closed, but the film and valve seat may stick together due to long-term contact, causing the channel to无法正常 open
Solution Approach 1:
The invention extracts the valve seat protruding structure from the system, eliminating the contact interface between the film and valve seat. The microchannel is directly formed in the lower substrate without a separate protruding valve seat, so the film never contacts a raised valve seat surface that could cause sticking.
Solution Approach 2:
Instead of having a protruding valve seat that the film contacts, the invention inverts the approach by having the microchannel formed directly in the substrate and the film positioned flush with the substrate surface. The sealing is achieved through the film conforming to the substrate surface rather than contacting a protruding valve seat.
2Reliability
If a protruding valve seat and recessed hollow cavity structure is used, then the microvalve can control fluid flow, but the thickness of the microfluidic chip is restricted and miniaturization cannot be achieved
Solution Approach 1:
The invention removes the protruding valve seat structure that added to the chip thickness. The microchannel is formed directly in the lower substrate, and the film is positioned flush with the substrate surface, eliminating the need for a recessed hollow cavity and significantly reducing the overall chip thickness.
Solution Approach 2:
The invention transitions from a three-dimensional protruding valve seat structure to a two-dimensional planar structure where the microchannel is formed in the substrate plane and the film seals against the substrate surface, reducing the vertical dimension and enabling miniaturization.
3Reliability
If external forces are used to deform the film and open the microvalve, then the flow channel can be opened, but another external force is required to act on the fluid to cause flow, making it difficult to control fluid flow precisely
Solution Approach 1:
The invention merges the valve opening function and fluid flow control into a single mechanism. When the film is deformed to open the valve, the same deformation creates a pressure difference that drives fluid flow through the microchannel, eliminating the need for separate actuation forces.
Solution Approach 2:
The invention uses pneumatic pressure generated by film deformation to drive fluid flow. When the film is deformed by external force, it creates a pressure difference across the microchannel that propels the fluid through the channel, combining valve actuation and fluid propulsion in one action.
4Reliability
If the microvalve is opened and the film contacts the fluid, then the valve can control flow, but the film cannot restore to the closed state, limiting reusability
Solution Approach 1:
Instead of the film contacting a protruding valve seat that prevents closure, the invention inverts the approach by having the film seal against the substrate surface with the microchannel formed directly in the substrate. This allows the film to fully restore to its original position and achieve complete closure, enabling repeated use.
5Reliability
If the microvalve structure is optimized to address sticking and reusability issues, then performance improves, but the difficulty of processing and assembling the microfluidic chip increases
Solution Approach 1:
The invention segments the microchannel formation process from the valve film assembly process. The microchannel is formed directly in the lower substrate through standard microfabrication techniques, while the valve film is a separate component that is assembled onto the substrate, simplifying both processing and assembly.
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 design achieves precise control of multiple fluids, reduces contamination risk, simplifies processing, and enables long-term reagent storage, enhancing the usability and miniaturization of microfluidic chips.
Implementation Method 1
This external force can be pneumatic (for example, US Patent Application US 2013/0156658 A1 and U.S. Pat. No. 8,778,282 B2)
Implementation Method 2
heated and deformed (for example, Chinese Patent Application CN 102006936 A, US Patent Application US 2006/0243934 A1 and US 2015/0028235 A1)
Implementation Method 3
magnetic (for example, Chinese Patent Application CN 103244734 A)
Data Source
AI summary
A microvalve (8), comprising a first flow guide channel (841) for communicating with microchannels (401, 402, 403, 404) in a chip and a second flow guide channel (842) for communicating liquid storage recesses (11, 12) in the chip to the ambient atmosphere, wherein the first flow guide channel and the second flow guide channel do not communicate with each other. Also provided are a microfluidic chip (100) and a method for controlling the flow of a plurality of fluids in a microfluidic chip. The microfluidic chip (100) comprises a microvalve capable of controlling the flow of a fluid. The microfluidic chip has three position states, so as to control different fluids in the chip to sequentially flow in the chip. The microfluidic chip and the microvalve have simple structures, are convenient to assemble, are reusable, and can avoid the possibility of mutual contamination between fluids.