Microfluidic Check Valve With Pre-Stressed Spring Face Seal
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Solution Overview
Problem
There is a need for a check valve design that can be easily integrated into microfluidic devices during both prototyping and production stages, particularly in thermoplastic devices, which must be compatible with rapid prototyping methods like laser cutting and scalable to injection molding, while providing robust sealing and passive fluid manipulation without requiring external actuation.
Innovation Solution
The design incorporates a pre-stressed orthoplanar spring and a soft elastomeric pad, which together form a face seal against an annular boss, allowing for adjustable opening pressure and one-directional flow, and can be manufactured using common materials like thermoplastics and metals, enabling integration into both laser-cut and machined devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex lithography is used to provide miniaturized components, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces complex lithographic processes with a mechanical spring-based check valve design that can be manufactured using simpler rapid prototyping methods like laser cutting, while maintaining the required functional precision for microfluidic applications
Solution Approach 2:
The invention changes the manufacturing approach from precision lithography to rapid prototyping with adjustable spring parameters (wire diameter, coil diameter, number of coils) that can be tuned to achieve the desired cracking pressure and sealing performance without requiring complex lithographic processes
2Ease of manufacture
If rapid prototyping is used for manufacturing, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
The check valve is segmented into distinct components (spring, elastomeric pad, housing) that can be manufactured separately using rapid prototyping and then assembled, allowing each component to be optimized for its specific manufacturing process while maintaining overall functional precision
Solution Approach 2:
The use of an elastomeric pad instead of a rigid sealing component compensates for dimensional tolerances inherent in rapid prototyping, as the flexible material can deform to create a reliable seal even with slight variations in component dimensions
3Reliability
If a pre-stressed spring with elastomeric pad is used, then sealing reliability is improved, but device complexity increases
Solution Approach 1:
The spring and elastomeric pad are combined into an integrated valve assembly where the spring provides both the sealing force and the mechanical structure, eliminating the need for separate actuation mechanisms and reducing overall device complexity while maintaining reliable sealing
Solution Approach 2:
The pre-stressed spring automatically provides the sealing force needed to close the valve, and the valve opens and closes passively in response to pressure differential without requiring external actuation, making the system self-regulating and reducing complexity
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 a robust, adjustable, and low-backflow check valve that can be seamlessly integrated into various microfluidic devices, offering minimized dead volumes, ease of manufacture, and versatility in opening pressure adjustment, suitable for point-of-care diagnostics and scalable production.
Implementation Method 1
the spring presses against the pad and provides a pressurized seal
Data Source
AI summary
The present invention relates to microfluidic check valves, as well as fluidic cartridges including such check valves. In particular examples, the check valve includes a pre-stressed spring formed from a planar substrate. Various characteristics of the valves, such as size, profile, opening pressure, etc., can be tuned to provide desired performance when employed within a fluidic cartridge.