Silicone Hydrogel Byproduct Normalization for Oxygen Permeability
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Solution Overview
Problem
The challenge lies in controlling the concentration of difunctional byproducts in silicone-containing monomers used for contact lens production, as they significantly impact the mechanical properties and water content of the lenses, leading to variability in oxygen permeability and comfort during extended wear.
Innovation Solution
A process involving the formation of a monomer mixture with a normalizing amount of difunctional silicone-containing byproducts is introduced, ensuring consistent concentrations and properties by adding a specific amount of difunctional byproducts to the monomer mix, which includes monofunctional silicone components and hydrophilic components, and curing the mixture to form silicone hydrogels with controlled mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicone monomers are included to increase oxygen permeability, then oxygen permeability is improved, but the concentration of difunctional byproducts increases which affects mechanical properties
Solution Approach 1:
The patent applies parameter changes by carefully controlling the concentration of difunctional byproducts within a specific range (0.1-5 wt%). By adjusting this parameter, the invention achieves both improved oxygen permeability and acceptable mechanical properties, resolving the contradiction between enhancing permeability and controlling byproduct concentration.
Solution Approach 2:
The patent converts the harmful effect of difunctional byproducts into a beneficial outcome by adding them in controlled amounts to enhance oxygen permeability. The byproducts, which were previously considered impurities reducing mechanical properties, are instead utilized as functional components that improve lens performance when present at optimized concentrations.
2Manufacturing precision
If difunctional byproducts are added to control concentration, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-dosing the difunctional byproduct concentrations in the monomer mixture before polymerization. This advance preparation ensures precise final concentrations without requiring complex real-time adjustments during the curing process, thereby improving manufacturing precision while limiting process complexity.
Solution Approach 2:
The patent implements feedback mechanisms through analytical testing during development and quality control to verify and adjust byproduct concentrations. This feedback loop enables precise control of difunctional byproduct levels, ensuring consistent mechanical properties and oxygen permeability while maintaining manageable process complexity through data-driven optimization.
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
This approach results in silicone hydrogels with uniform physical properties, enhanced oxygen permeability, and improved comfort by maintaining desired mechanical properties such as water content, modulus, and elongation, ensuring consistent performance of contact lenses during extended wear.
Implementation Method 1
curing said monomer mixture to form a biomedical device
Data Source
AI summary
The present invention relates to a process comprising forming a monomer mixture comprising at least one monofunctional silicone containing component which comprises at least one difunctional byproduct and adding to said monomer mixture a normalizing amount of said at least one difunctional byproduct and curing said monomer mixture to form a biomedical device.