Radiative Cooling Fabric with Void Structures for Solar Reflectivity

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Solution Overview

Problem

There is a need for techniques to fabricate radiative cooling fabrics or fibers with improved optical effects, similar to those of comet moth silk fibers, which provide radiative cooling through enhanced solar reflectivity and thermal emissivity.

Innovation Solution

The development of a system comprising a fabric with fibers that include void structures, which scatter electromagnetic radiation to radiatively cool an object, and can be made from natural and synthetic materials such as silk fibroin, cellulose, nylon, and PVDF, with void structures that enhance solar reflectivity and thermal emissivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional fabrics are used, then manufacturing is simple and cost-effective, but solar reflectivity and thermal emissivity are insufficient for effective radiative cooling

Engineering Contradiction:

Improveradiative cooling effectivenessVSAvoidfabric structure complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent applies porous materials by incorporating void structures within fibers at controlled concentrations (e.g., 1-50 voids per mm²) to enhance solar reflectivity and thermal emissivity. The voids create scattering centers that reflect solar radiation while maintaining thermal radiation emission in the mid-infrared range, achieving radiative cooling without complex multi-layer structures.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent uses composite materials by combining fibers with different properties (natural and synthetic fibers) and incorporating nanoparticles (titanium dioxide, zinc oxide, aluminum oxide, silicon dioxide, barium titanate) into the fabric structure. This composite approach enables simultaneous optimization of solar reflectivity, thermal emissivity, and mechanical properties while maintaining manufacturing feasibility.

Inventive Principle:

Principle #40Composite materials

2Temperature

If void structures are introduced into fibers to enhance solar reflectivity, then radiative cooling performance improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvesolar reflectivityVSAvoidvoid structure control

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by controlling void concentration (1-50 voids per mm²), void size (10 nm to 10 μm diameter), and nanoparticle concentration to optimize solar reflectivity. By systematically varying these parameters, the patent achieves enhanced radiative cooling performance while maintaining manufacturability through established textile processing techniques.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by positioning void structures and nanoparticles at specific locations within fibers and fabric layers. Void structures are distributed throughout fiber cross-sections, while nanoparticles are concentrated at fiber interfaces and void boundaries, creating localized optical properties that maximize solar reflection and thermal emission efficiency.

Inventive Principle:

Principle #3Local quality

3Temperature

If nanoparticles are added to enhance optical scattering, then solar reflectivity increases, but material cost and processing complexity increase

Engineering Contradiction:

Improvethermal emissivityVSAvoidfabric processing

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent applies universality by selecting nanoparticles (titanium dioxide, zinc oxide, aluminum oxide, silicon dioxide, barium titanate) that serve multiple functions: enhancing solar reflectivity through scattering, improving thermal emissivity in the mid-infrared range, and providing UV protection. This multi-functionality reduces the need for additional specialized materials and simplifies the overall fabrication process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 system effectively radiatively cools objects by scattering solar radiation and dissipating heat as thermal blackbody radiation, while also exhibiting enhanced solar reflectivity and thermal emissivity, similar to natural comet moth silk fibers.

Implementation Method 1

The void structures can scatter at least a portion of an electromagnetic radiation received thereon to thereby radiatively cool the object

Methodology Applied

Scientific EffectScattering: Scattering

Implementation Method 2

the void structures can scatter at least a portion of an electromagnetic radiation received thereon to thereby radiatively cool the object

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentUS12222169B2Devices and methods for radiative cooling

Publication Date: 2025.02.11 THE TRUSTEES OF COLUMBIA UNIV IN THE CITY OF NEW YORK

AI summary

Devices for radiative cooling and optical waveguiding are provided, wherein the devices comprise a fabric including one or more fibers extending for a length in a longitudinal direction and a plurality of void structures positioned within each of the one or more fibers and extended over the length of each of the one or more fibers. Each of the plurality of void structures is configured to scatter at least a portion of an electromagnetic radiation received thereon to thereby radiatively cool the object.