Electrofluidic Smart Windows for Independent Infrared Reflection
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Solution Overview
Problem
Current smart window technologies are inadequate for actively managing solar heat gain across different climates and seasons, as they either fail to independently control infrared and visible light transmission or are unsuitable for exterior applications due to UV sensitivity and narrow reflectivity ranges.
Innovation Solution
An electrofluidic device that modulates near-infrared reflection and transmission properties in response to heating and cooling needs, using an electrofluidic layer with a pigmented fluid that changes its contact angle on a hydrophobic surface in response to voltage, allowing for independent control of infrared and visible light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional electrowetting displays with colored oil are used, then visible light transmission can be controlled with high contrast ratio, but infrared heat transmission cannot be independently managed
Solution Approach 1:
The patent segments the optical control function by using separate pigment layers: one layer for visible light absorption and another layer for infrared radiation reflection. This allows independent management of visible and infrared transmission through the window, resolving the contradiction between visible light control and infrared heat management capability.
Solution Approach 2:
The invention employs composite material structure with multiple functional layers including pigmented oils with different spectral properties. By combining visible-light-absorbing pigments and infrared-reflecting pigments in separate controllable layers, the system achieves both high contrast visible light control and independent infrared heat management.
2Loss of energy
If passive infrared-reflecting pigments are used on roofs and siding, then infrared reflection is improved, but visible light transmission is blocked
Solution Approach 1:
The patent separates the infrared reflection function from visible light absorption by placing infrared-reflecting pigments in a dedicated layer that is optically transparent to visible wavelengths. This segmentation allows the window to reflect infrared heat while maintaining full visible light transmission, eliminating the trade-off present in passive pigmented coatings.
Solution Approach 2:
The invention applies local quality by giving different layers specific spectral functions: the visible light control layer absorbs only in the visible range while remaining transparent to infrared, and the infrared control layer reflects only infrared while being transparent to visible light. This localized spectral selectivity resolves the contradiction between infrared reflection efficiency and visible light transmission.
3Loss of energy
If electrofluidic devices with infrared-reflecting pigments are deployed, then solar heat gain management is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent employs a universal electrofluidic device architecture that can accommodate different pigment combinations for various spectral control needs. The same basic device structure with replaceable pigmented oil layers can be manufactured using established electrowetting display fabrication processes, reducing complexity while enabling multi-functional spectral management.
Solution Approach 2:
The invention simplifies manufacturing by controlling spectral properties through parameter changes in the pigment composition and layer configuration rather than requiring fundamentally different device structures. By adjusting pigment concentration, particle size, and layer thickness, the same device architecture can be optimized for different spectral control requirements without increasing fabrication complexity.
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 electrofluidic device provides efficient management of solar heat gain, maintaining visible light transmission while minimizing infrared heat, and is environmentally stable and cost-effective, suitable for various climate zones and applications, including windows and skylights.
Implementation Method 1
an electrofluidic layer with a pigmented fluid that changes its contact angle on a hydrophobic surface in response to voltage
Implementation Method 2
The electrofluidic device provides efficient management of solar heat gain, maintaining visible light transmission while minimizing infrared heat
Data Source
AI summary
Methods, systems, devices and/or apparatuses are provided that selectively reflect the infrared spectrum independent of other regions of the solar spectrum in order to actively manage solar heat gain across surfaces such as windows, skylights, roofs, siding and the like.