Microfluidic Cassette Piercing Structure for Stable Reagent Mixing
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Solution Overview
Problem
Microfluidic diagnostic cassettes face issues with reagent degradation due to moisture exposure and irregular fluid flow, leading to reduced test accuracy and storage life, especially when using lyophilized reagents.
Innovation Solution
A microfluidic cassette design featuring first and second piercing members with additional fluid apertures that facilitate controlled fluid flow and mixing by providing alternative paths for fluid to enter or exit the reagent-containing chamber, even if the seal is partially occluded, ensuring regular and complete mixing with reagents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reagents are deposited directly onto the fluid flow channel during manufacturing, then the cassette can be sealed during manufacture, but moisture from the atmosphere or vapour from stored fluids can contact and degrade the reagent over time
Solution Approach 1:
The reagent storage is segmented from the fluid flow channel by introducing a separate reagent-containing chamber with its own seal. This physical segmentation prevents moisture from the atmosphere or stored fluids from contacting the reagent, while still allowing controlled fluid communication when needed for the diagnostic test.
Solution Approach 2:
The reagent-containing chamber is nested within the cassette structure, with the seal breaking structure integrated into the cassette body. The chamber is positioned such that it can be sealed during manufacture and then selectively accessed during use, protecting the reagent while maintaining system integration.
2Reliability
If a foil seal is used to seal the reagent-containing chamber, then external materials are prevented from contacting the reagent, but the foil seal can partially occlude the seal breaking structure after being broken, reducing fluid flow rate and mixing
Solution Approach 1:
The piercing member is designed with differentiated local qualities: a sharp distal end for effectively breaking the foil seal, and a smooth surface to minimize foil occlusion. The further fluid aperture is strategically positioned on the portion of the wall facing away from the second piercing member, creating a localized alternative flow path that ensures adequate fluid communication even when the seal partially occludes the primary path.
Solution Approach 2:
The invention adds a dimensional solution by providing a further fluid aperture on the lateral wall of the first piercing member rather than relying solely on the distal end aperture. This alternative dimension for fluid flow ensures that even if the foil seal occludes the primary path through the distal end, fluid can still enter the reagent-containing chamber through the lateral aperture, maintaining adequate flow rate and mixing.
3Reliability
If the foil seal is broken in situ in the cassette, then reagent remains sealed until use, but pressure can build up behind the fluid sample as flow rate reduces, causing loss of control and break-up of the fluid sample
Solution Approach 1:
The further fluid aperture on the lateral wall of the first piercing member provides an additional dimension for pressure relief. When the foil seal breaks and the sample encounters resistance, pressure can build up and force fluid through this alternative lateral path, preventing dangerous pressure accumulation and maintaining controlled fluid flow through the reagent-containing chamber.
Solution Approach 2:
The further fluid aperture acts as a pre-established pressure relief path. Before pressure buildup becomes problematic, this alternative aperture is already in place to cushion and regulate pressure fluctuations, ensuring smooth and controlled fluid flow through the reagent chamber during the diagnostic test.
Data Source
AI summary
A microfluidic cassette has a microfluidic cassette body. The microfluidic cassette body has a fluid flow channel, a first piercing member comprising a wall extending out from the microfluidic cassette body, the wall enclosing a first fluid aperture that is in fluid communication with the fluid flow channel, and a second piercing member comprising a wall extending out from the microfluidic cassette body adjacent to the first piercing member, the wall enclosing a second fluid aperture that is in fluid communication with the fluid flow channel. The first piercing member has a further fluid aperture located on a portion of the wall of the first piercing member facing away from the second piercing member.