Multilayer Polyurethane Membrane for Liquid Lens Optical Clarity
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Solution Overview
Problem
Current liquid lenses face challenges in achieving a transparent, optically clear elastic membrane with reproducible elastic response under small strains over multiple actuation cycles while maintaining effective barrier properties against liquid lens fluids.
Innovation Solution
The development of multilayer polyurethane-based membranes with a bi-layer or tri-layer structure, incorporating thermoplastic or thermoset polyurethane layers and barrier layers, which are optically transparent and exhibit elastic response under small strains, along with an antireflective coating for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer elastic membrane is used in liquid lenses, then the device complexity is reduced, but the membrane cannot simultaneously provide both effective barrier properties and reproducible elastic response under small strains
Solution Approach 1:
The patent applies composite materials by combining polyurethane layers with barrier layers to create a multilayer membrane structure. This composite approach allows the membrane to simultaneously achieve effective barrier properties against liquid lens fluids and reproducible elastic response under small strains, resolving the contradiction between device simplicity and performance reliability.
Solution Approach 2:
The patent segments the membrane into multiple functional layers, including polyurethane layers for elastic response and barrier layers for fluid protection. This segmentation allows each layer to specialize in its function, enabling the overall membrane to meet both elastic and barrier requirements that a single-layer structure cannot satisfy.
2Loss of substance
If barrier layers with high fluid resistance are used, then fluid transpiration is reduced, but optical clarity and light transmissivity deteriorate
Solution Approach 1:
The patent uses composite materials by combining transparent barrier layers with optically clear polyurethane layers. The barrier layers are designed to provide fluid resistance while maintaining optical transparency, and when combined with the polyurethane layers, the overall structure achieves both low fluid transpiration and high light transmissivity.
Solution Approach 2:
The patent applies local quality by optimizing the thickness and material composition of individual layers. The barrier layers are made thin enough to maintain optical clarity while still providing effective fluid resistance, and are strategically positioned within the multilayer structure to minimize impact on light transmission while maximizing barrier performance.
3Illumination intensity
If the membrane is made thinner to improve optical clarity, then light transmissivity increases, but barrier properties against liquid lens fluids deteriorate
Solution Approach 1:
The patent segments the barrier function across multiple thin barrier layers within the multilayer structure. While each individual barrier layer is thin to maintain optical clarity, the cumulative effect of multiple layers provides effective fluid barrier performance, resolving the contradiction between thinness for optical clarity and thickness for barrier protection.
Solution Approach 2:
The patent uses composite materials where transparent barrier layers are combined with polyurethane layers in a multilayer configuration. This composite structure allows the overall membrane to achieve both high light transmissivity (through optimized total thickness and material selection) and effective fluid barrier properties (through the combined protective effect of multiple layers).
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 multilayer membranes provide a stable, reproducible elastic response and effective barrier properties, maintaining optical clarity and reducing fluid transpiration, while the antireflective coating ensures high transmissivity and low reflectivity over multiple actuation cycles.
Implementation Method 1
exhibit elastic response under small strains over multiple actuation cycles
Implementation Method 2
effective barrier layer properties... limiting transpiration of liquid lens fluids
Implementation Method 3
antireflective coating formed over the multilayer polyurethane-based membrane... ensuring high transmissivity and low reflectivity
Data Source
AI summary
A liquid lens includes a transparent substrate, a multilayer polyurethane-based membrane overlying the transparent substrate, and a liquid layer disposed between and abutting the transparent substrate and the multilayer polyurethane-based membrane. The multilayer polyurethane-based membrane, which may include thermoplastic and/or thermoset polymer layers, may be formed by slot die coating or gravure coating one or more constituent layers and may exhibit a reversible elastic response to imposed strains of up to approximately 5% while limiting the transpiration of fluid therethrough to less than approximately 10−2 g/m2/day.