Contact Lens Microfluidic Channel for Corneal Curvature Monitoring
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Solution Overview
Problem
Current methods for monitoring the radius of curvature of the cornea, essential for glaucoma management, are expensive, uncomfortable, and lack long-term viability due to gas permeability issues and non-linear sensor behavior caused by high surface energy of sensing liquids in existing contact lenses.
Innovation Solution
A contact lens with an integrated microfluidic channel that converts changes in corneal curvature into gas/liquid interface movement, detectable by an external imaging system, using non-gas-permeable materials and a low surface tension working fluid to ensure high sensitivity, linearity, and extended wearability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDMS material is used in existing contact lenses for microfluidic channels, then the device can be manufactured, but gas leakage occurs causing short lifetime
Solution Approach 1:
The patent changes the material parameter from PDMS to non-gas-permeable materials such as parylene-C, silicon nitride, or silicon oxide for the microfluidic channel walls, eliminating gas permeability while maintaining manufacturability through standard semiconductor fabrication techniques
Solution Approach 2:
The contact lens employs a composite structure combining gas-impermeable microfluidic channel materials (parylene-C, silicon nitride) with contact lens materials, creating a multi-layer composite that simultaneously achieves gas tightness and optical/biological compatibility
2Measurement precision
If high surface energy sensing liquid is used in existing contact lenses, then the liquid can be contained, but high capillary pressure drop causes non-linear sensor behavior
Solution Approach 1:
The patent changes the surface tension parameter of the sensing liquid from high to low by selecting liquids such as perfluorocarbon or alcohol-based solutions, which reduces capillary pressure drop and enables linear sensor response while maintaining adequate liquid containment through surface energy management
3Measurement precision
If electrical components and connections are used for measuring radius of curvature, then measurement can be achieved, but the device becomes expensive and uncomfortable
Solution Approach 1:
The patent replaces electrical measurement systems with an optical-mechanical system where a microfluidic channel converts radius of curvature changes into gas/liquid interface displacement, which is then detected optically by an external imaging system, eliminating the need for electrical components within the contact lens
Solution Approach 2:
The patent introduces a working liquid as an intermediary that transmits mechanical deformation from the cornea to the gas/liquid interface in the microfluidic channel, enabling indirect measurement of radius of curvature through optical detection of interface position rather than direct electrical sensing
4Duration of action of moving object
If existing contact lenses with microfluidic channels are designed, then IOP monitoring is possible, but the lifetime is less than 24 hours due to gas permeability
Solution Approach 1:
The patent fundamentally changes the gas permeability parameter of the microfluidic channel material from permeable (PDMS) to impermeable (parylene-C, silicon nitride), enabling the contact lens to maintain its sealing integrity and functional reliability for extended wear periods exceeding 24 hours
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 low-cost, daily-wearable contact lens for continuous monitoring of corneal curvature changes, improving glaucoma treatment effectiveness and longevity by overcoming gas leakage and non-linear sensor issues.
Implementation Method 1
the enclosed gas volume is configured to change in volume in response to changes in the radius of curvature of the cornea
Implementation Method 2
The microfluidic channel converts the changes in the radius of corneal curvature into gas/liquid interface movement inside the microfluidic channel
Implementation Method 3
the movement of gas/liquid interface can be optically detected by utilizing an external imaging system that includes components such as a camera, a lens, a microscope and a light source
Data Source
AI summary
a contact lens that monitors the radius of curvature of cornea includes an amplification chamber, am annular membrane, a microfluidic channel, and a gas reservoir within a top and bottom lens layers of the contact lens. The annular membrane is positioned within the amplification chamber and is in fluid communication with the gas reservoir through the microfluidic channel. A working gas within the gas reservoir and a working fluid within the amplification chamber and the microfluidic channel create a fluid-gas equilibrium pressure interface. The curvature change of the cornea results the amplification chamber wall and the annular membrane to deflect, wherein the deflection results the fluid-gas equilibrium pressure interface baseline to change within the microfluidic channel. Then the baseline position change is recorded by an external imaging system to analysis sensitivity calculation of the cornea.