Spring-Loaded Membrane Valve for Microfluidic Sealing
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Solution Overview
Problem
Microfluidic systems in lab-on-a-chip (LOC) devices face challenges in reliably sealing and controlling the transfer of liquid reagents due to the flexibility of membrane layers, which can lead to leaks and inconsistent sealing, especially under pressure fluctuations.
Innovation Solution
A valve assembly with a spring element that presses a resilient membrane layer against a web-like projection, using a compressible material like a helical spring or foam, ensuring a consistent sealing force and allowing for adjustable sealing pressure, and an external cutting element to open the valve by severing the spring arm, facilitating controlled fluid communication between recesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a resilient membrane layer is used to seal the recesses, then the valve can be actuated by pressure differential, but the sealing reliability deteriorates under pressure fluctuations due to membrane flexibility
Solution Approach 1:
The patent introduces a spring element that applies a predetermined compressive force to the membrane layer, changing the mechanical parameters of the sealing interface. This pre-compression ensures consistent contact between the membrane and the sealing surface, maintaining sealing reliability even when pressure differentials act on the membrane during valve operation.
Solution Approach 2:
The spring element acts as a cushioning mechanism that compensates for pressure fluctuations before they can compromise the seal. By pre-loading the membrane with compressive force, the system is prepared to maintain sealing under varying pressure conditions without requiring active control during operation.
2Adaptability or versatility
If the membrane flexibility is increased to enable valve actuation, then the valve can open under overpressure, but the sealing tightness deteriorates allowing fluid leakage
Solution Approach 1:
The spring element modifies the force balance at the sealing interface by applying a predetermined compressive force. This changes the critical parameter of contact pressure, ensuring that the membrane maintains sufficient contact with the sealing surface to prevent leakage while still allowing actuation when the pressure differential exceeds the spring force.
Solution Approach 2:
The spring element performs a preliminary action by pre-compressing the membrane layer before the valve operates. This preliminary compression establishes a baseline sealing force that must be overcome by the pressure differential to open the valve, thereby controlling both sealing tightness and actuation conditions.
3Device complexity
If no additional actuation connections are provided, then the device complexity is reduced, but the ease of operation deteriorates making valve control difficult
Solution Approach 1:
The valve assembly is designed to be self-actuating through the pressure differential that naturally occurs during fluid flow. The spring-loaded membrane automatically responds to pressure changes in the fluid system, opening or closing the valve without requiring external actuation mechanisms, connections, or control systems.
Solution Approach 2:
The valve utilizes the hydraulic pressure of the fluid itself as the actuation mechanism. The pressure differential across the membrane, generated by the fluid flow conditions, directly actuates the valve by overcoming the spring force, eliminating the need for separate pneumatic or hydraulic actuation systems.
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 solution provides improved sealing reliability and adjustable sealing force, ensuring effective containment of reagents during transport and storage, while allowing for easy actuation of the valve without additional connections, thus addressing the issues of pressure fluctuations and reagent handling in LOC systems.
Implementation Method 1
a spring element disposed in the recess of the upper substrate component and urging the membrane layer onto the protrusion
Implementation Method 2
the membrane is displaced from the projection in the direction of the recess in the upper substrate component and thus creates a fluid connection between one recess in the lower substrate component and the other recess in the lower substrate component
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The valve assembly (10) has a lower substrate component (20) that is provided with two recesses (50,60). The recesses are separated by a web-like projection (70). An upper substrate component (30) is mounted on the lower substrate component. A fluid impermeable flexible membrane layer (40) is provided between the upper and lower substrate components. A spring element (80) is arranged in a recess (110) of the upper substrate component and the membrane layer is pressed on the projection, so that the valve assembly is in closed operation state.