Blister Seal Structure for Controlled Reagent Release
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Solution Overview
Problem
Ensuring that the backing foil sealing liquid-filled blisters in diagnostic cartridges provides a durable and sterile storage solution while reliably failing at the desired location under pressure, without compromising the seal's integrity.
Innovation Solution
A blister sub-assembly design with a first layer and a second layer sealed at the periphery, featuring a first peel strength and a second peel strength, and incorporating discontinuities in the seal to require a shear force for delamination, enhancing the seal's peel strength and ensuring controlled ejection of contents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the backing foil is made strong to provide durable and sterile storage, then storage integrity is improved, but the foil may not reliably fail at the desired location when pressure is applied
Solution Approach 1:
The seal between the first and second layers is segmented into two distinct portions: a first portion with higher peel strength and a second portion with lower peel strength. This segmentation allows the seal to have different failure characteristics in different regions, enabling controlled failure at the second portion while maintaining overall seal integrity for storage.
Solution Approach 2:
Different portions of the seal are given different local qualities in terms of peel strength. The first portion has higher peel strength to maintain storage integrity, while the second portion has lower peel strength to fail reliably under pressure. This local differentiation resolves the contradiction between overall strength and controlled failure.
2Ease of operation
If the seal between first and second layers is made weak to allow controlled release, then reagent ejection is improved, but the seal integrity during storage is compromised
Solution Approach 1:
The seal is divided into functional segments: a first portion with higher peel strength for storage integrity and a second portion with lower peel strength for controlled ejection. This segmentation allows the seal to simultaneously provide both strong storage protection and reliable controlled failure.
Solution Approach 2:
The peel strength parameter is varied across different portions of the seal. By changing the peel strength from high in the first portion to low in the second portion, the seal achieves both storage integrity and controlled ejection functionality.
3Strength
If discontinuities are added to the seal to increase peel strength, then seal robustness is improved, but manufacturing complexity increases
Solution Approach 1:
The seal is segmented into portions with different peel strengths, with discontinuities strategically placed in the first portion. This segmentation approach increases peel strength by creating a more complex seal structure that requires both peel and shear forces to fail.
4Strength
If the fluid-filled blister acts to delaminate the first and second layers at the seal margin, then the layers separate, but the seal fails at the wrong location
Solution Approach 1:
The seal's local quality is differentiated by creating portions with different peel strengths. The first portion has higher peel strength to resist fluid-induced delamination, while the second portion has lower peel strength to fail reliably at the desired location when pressure is applied.
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 ensures robust and controlled release of reagents by increasing the peel strength of the seal, preventing premature failure and maintaining the integrity of the blister assembly during storage and ejection.
Implementation Method 1
the seal between the first and second layers comprises a first planar portion having a first peel strength and a second planar portion having a second peel strength, wherein the first peel strength is greater than the second peel strength, such that when pressure is applied to the blister, the second portion of the seal breaks to release the liquid contained within the chamber
Implementation Method 2
wherein the blister sub-assembly further comprises at least one discontinuity formed in the first and second layers in the region of the first portion of the seal, such that a shear force is required to delaminate the first and second layers in that region
Data Source
AI summary
A blister assembly comprises at least one collapsible blister adapted, as it is collapsed, to eject a liquid contained therein. The blister assembly comprises a first layer (130) having at least one blister chamber (150) and a second layer (131) sealed to the first layer at least around a periphery of the at least one blister chamber such that a liquid is contained between the first layer and the second layer. The seal between the first and second layers comprises a first planar portion having a first peel strength and a second planar portion having a second peel strength, wherein the first peel strength is greater than the second peel strength, such that when pressure is applied to the blister, the second portion of the seal breaks to release the liquid contained within the chamber into the liquid inlet. The blister assembly further comprises at least one discontinuity (142) formed in the first and second layers in the region of the first portion of the seal, such that a shear force is required to delaminate the first and second layers in that region.