Contact Lens Coating Analysis in Hydrated ESEM Conditions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for characterizing the thickness and features of contact lens coatings, particularly those with a water gradient, are inadequate, especially when the coatings are dried or frozen, leading to artifacts that distort the true coating properties.
Innovation Solution
Utilize environmental scanning electron microscopy (ESEM) to analyze contact lens coatings in fully hydrated conditions or high relative humidity environments, allowing precise measurement of coating thickness and structure without drying or freezing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electron microscopy is used to analyze contact lens coatings, then coating thickness and structure can be measured, but drying or freezing artifacts distort the true coating properties
Solution Approach 1:
The patent changes the environmental parameters of the microscopy analysis by using environmental scanning electron microscopy (ESEM) that allows analysis in fully hydrated conditions or high relative humidity environments, rather than requiring dried or frozen samples. This parameter change eliminates artifacts while maintaining measurement precision.
Solution Approach 2:
The patent introduces a controlled humid environment as an intermediary medium between the sample and the vacuum chamber of the electron microscope. This intermediary allows the coating to maintain its natural hydrated state during analysis, preventing the formation of drying or freezing artifacts that would otherwise distort the measurement.
2Ease of manufacture
If contact lens coatings are dried or frozen for analysis, then sample preparation is simplified, but artifacts are introduced that distort true coating properties
Solution Approach 1:
The patent changes the environmental conditions under which samples are analyzed, allowing fully hydrated samples to be examined without requiring drying or freezing preparation steps. This eliminates artifact formation while maintaining coating thickness measurement accuracy.
3Use of energy by moving object
If silicone is incorporated in contact lens material to achieve high oxygen permeability, then oxygen transport ability is improved, but biocompatibility deteriorates due to hydrophobic silicone migration to surface
Solution Approach 1:
The patent applies local quality modification by creating a surface coating with different properties than the bulk material. The coating is designed with a water gradient where water content varies through the thickness, creating a hydrophilic surface layer that improves biocompatibility while the bulk material maintains high oxygen permeability through silicone content.
Solution Approach 2:
The patent uses composite material structure by combining silicone hydrogel bulk material with a separate surface coating layer. The coating material is selected from polymers that can form hydrophilic surfaces, creating a composite structure where each layer performs its specific function: oxygen transport in the bulk and biocompatibility at the surface.
Data Source
Figure 1
Figure 2
AI summary
Use of high resolution environmental scanning electron microscopy to capture images of contact lens coating layers, enabling measurement of the coating thickness and structures of the coating layer to be precisely characterized. The coating layer can be directly visualized and quantitatively measured. Furthermore, controlled environments of varying temperatures and varying levels of relative humidity can be established in environmental scanning electron microscopy, such that the dynamic changes of the coating in such conditions can be imaged and measured. The controlled environments can be set up to mimic either the manufacturing process conditions, or be set up to simulate lens-on-eye conditions.