Colored Fluids for Electrowetting Using Non-Aqueous Solvents
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Solution Overview
Problem
Conventional electrowetting devices face limitations due to the use of water and dyes, which result in poor light and weather fastness, high cost, inadequate solubility, and low resistance to bleed, necessitating improved colored fluids for enhanced performance and durability.
Innovation Solution
Development of colored fluids comprising non-aqueous polar and non-polar solvents with specific viscosity, surface tension, and electrowetting relative response, combined with organic pigments or dyes, to create stable and durable colored fluids for electrowetting, electrofluidic, and electrophoretic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If water and conventional dyes are used in electrowetting devices, then the device can operate with simple composition, but the light and weather fastness deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by replacing water with non-aqueous polar solvents (such as propylene carbonate, gamma-butyrolactone, diethylene glycol) and using organic pigments instead of conventional dyes. This parameter change maintains the fluid's electrowetting functionality while dramatically improving light and weather fastness, as the non-aqueous solvent system is more resistant to photodegradation and environmental factors.
Solution Approach 2:
The patent creates a composite colored fluid system combining non-aqueous polar solvents with organic pigments and optional additives. This composite approach allows the fluid to achieve both the required electrowetting properties and enhanced durability, as the organic pigment provides superior light fastness while the non-aqueous solvent matrix maintains compatibility with the electrowetting device architecture.
2Ease of manufacture
If dyes are used as colorants, then the device can be manufactured with simpler processes, but the cost increases and solubility in non-polar solvents deteriorates
Solution Approach 1:
The patent changes the solvent polarity parameter by selecting non-aqueous polar solvents with specific dielectric constants and viscosities that are compatible with organic pigments. This parameter change enables the use of organic pigments that have better solubility and stability in non-polar environments, while the overall manufacturing process remains relatively simple through direct mixing of components.
Solution Approach 2:
The patent adopts the successful formulation approach of organic pigment systems used in other optical and display applications, adapting that proven model to electrowetting devices. This copying of established formulation techniques allows for straightforward manufacturing while achieving superior solubility and color stability.
3Quantity of substance
If dyes are used for coloring, then the initial cost may be lower, but the resistance to bleed deteriorates
Solution Approach 1:
The patent formulates a composite system where organic pigments are dispersed in a non-aqueous polar solvent matrix, creating a colored fluid with enhanced resistance to bleed. The organic pigment provides superior binding and resistance to migration compared to conventional dyes, while the non-aqueous solvent system further stabilizes the colorant and prevents bleeding during device operation.
4Device complexity
If water is used in electrowetting devices, then the device can maintain simple physical properties, but the application range is limited due to expansion at higher temperature and freezing point
Solution Approach 1:
The patent changes the solvent's thermal and phase transition parameters by replacing water with non-aqueous polar solvents that have broader operating temperature ranges. These solvents (such as propylene carbonate, gamma-butyrolactone, diethylene glycol) have higher freezing points and lower expansion coefficients, allowing the device to operate reliably in a wider range of environmental conditions without the physical property changes that limit water-based systems.
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 new colored fluids provide improved durability, higher chroma, faster switching speeds, and lower power consumption, while maintaining desired color properties over time, enhancing the performance of electrowetting and electrofluidic devices.
Implementation Method 1
The term 'electrowetting' describes the effects of an electric field on the contact angle of a liquid with a hydrophobic surface. With an electric field, the liquid distributes over, or wets, a surface that initially repels the liquid resulting in a change in the spectral properties of a device.
Implementation Method 2
A plurality of electrodes is configured to apply a potential difference effective to move the colored fluid relative to at least one of the electrodes.
Data Source
AI summary
Colored fluids for electrowetting, electro fluidic, or electrophoretic devices, and the devices themselves, are disclosed. The colored fluid can include a nonaqueous polar solvent having (a) a dynamic viscosity of 0.1 cP to 50 cP at 250 C, (b) a surface tension of 25 dynes/cm to 55 dynes/cm at 250 C, and (c) an electrowetting relative response of 40% to 80%. Such colored fluids further include a colorant selected from a pigment and/or a dye. In another embodiment, the colored fluid can include a non-polar solvent and an organic colorant selected from a pigment and/or a dye. Such colored fluids can be black in color and have a conductivity from 0 pS/cm to 5 pS/cm and a dielectric constant less than 3. The use of the colored fluids offers improvements in reliability, higher levels of chroma in the dispersed state, and the ability to achieve higher contrast ratios in display technologies.