Plasmonic ZnO Sunscreen Particles for UV Absorption
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Solution Overview
Problem
Existing sunscreen compositions using zinc oxide (ZnO) particles face challenges in effectively blocking the entire UV light spectrum without causing whitening effects due to light scattering, especially in high SPF formulations which require higher particle densities.
Innovation Solution
Embedding metal particles with specific plasmon resonance frequencies into zinc oxide particles to enhance light absorption capabilities, thereby blocking UV light across the entire spectrum while minimizing visible light scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If higher density of ZnO particles is added to achieve high SPF and block more UV light, then UV light absorption is improved, but the composition becomes white and opaque due to light scattering
Solution Approach 1:
The patent combines ZnO particles with metal particles (such as gold or silver) to create composite structures. The metal particles exhibit plasmonic resonance that enhances UV light absorption by the ZnO, allowing effective UV blocking at lower ZnO concentrations, thereby reducing visible light scattering and whitening effects.
Solution Approach 2:
The patent modifies the optical properties of ZnO by introducing metal particles with specific plasmon resonance frequencies. This changes the absorption characteristics of the composition, enabling enhanced UV absorption without proportionally increasing visible light scattering, thus resolving the contradiction between UV protection and cosmetic appearance.
2Object-affected harmful factors
If ZnO particle size is reduced to improve UV absorption, then UV light blocking capability is improved, but light scattering increases causing whitening
Solution Approach 1:
By embedding metal particles within or on ZnO particles, the composite structure enhances the UV absorption efficiency of each particle. This allows smaller ZnO particles to maintain or improve UV blocking capability while reducing the overall particle density needed, thereby minimizing light scattering and whitening.
Solution Approach 2:
The metal particles are strategically positioned within or on the ZnO particles to create localized plasmonic resonance fields that enhance UV absorption in specific regions. This localized enhancement allows for reduced overall particle concentration while maintaining UV protection, thus reducing visible light scattering.
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 effectively blocks UV light from 280 to 400 nm and prevents whitening by maximizing plasmonic enhancement of absorption, ensuring broad-spectrum protection without the undesirable opaque appearance.
Implementation Method 1
selecting one or more metal particles to be used in conjunction with one or more zinc oxide particles in a sunscreen composition, wherein said selecting is based on the plasmon resonance frequency associated with each of the metal particles
Data Source
AI summary
Zinc oxide compositions as well as techniques for plasmonic enhancement of absorption in sunscreen applications are provided herein. A method includes selecting one or more metal particles to be used in conjunction with one or more zinc oxide particles in a sunscreen composition, wherein said selecting is based on the plasmon resonance frequency associated with each of the metal particles; and embedding the one or more selected metal particles into each of the one or more zinc oxide particles.