Doped Zinc Oxide Particles for Sunscreen UV Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sunscreen compositions with high sun protection factor (SPF) require higher densities of zinc oxide (ZnO) particles to block UV light, leading to undesirable whitening effects due to light scattering in the visible spectrum.
Innovation Solution
Incorporating dopants such as chromium, cobalt, gallium, and tin into ZnO particles to modify their optical properties, increasing absorption across the UV spectrum (280-400 nm) while minimizing scattering effects by adjusting the band gap and introducing additional electronic states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher density of ZnO particles is added to achieve high SPF, then UV light blocking capability is improved, but light scattering in visible spectrum increases causing whitening effects
Solution Approach 1:
The patent applies parameter changes by doping ZnO particles with transition metals (Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn) to modify the electronic band structure and optical properties. This changes the absorption spectrum to extend into the visible range (400-700 nm) while maintaining UV blocking, thereby reducing light scattering and whitening effects without compromising SPF performance
Solution Approach 2:
The patent creates composite materials by incorporating dopant elements into the ZnO crystal lattice. These doped ZnO particles exhibit enhanced optical properties compared to pure ZnO, achieving both superior UV absorption and reduced visible light scattering through the synergistic effect of the host matrix and dopant elements
2Reliability
If ZnO particle density is increased to absorb more UV light, then sun protection factor is improved, but composition becomes white and opaque
Solution Approach 1:
The patent modifies the optical parameters of ZnO particles through doping, which alters the band gap energy and introduces intermediate energy states. This enables the particles to absorb UV light effectively while allowing visible light to pass through, thereby maintaining transparency and achieving high SPF without compromising illumination intensity
3Reliability
If more ZnO particles are used to block complete UV spectrum, then UV absorption range is improved, but light scattering effects increase
Solution Approach 1:
The patent changes the optical parameters of ZnO particles by introducing dopant elements that modify the electronic band structure. This extension of absorption into the visible spectrum reduces the energy available for scattering processes, thereby minimizing light scattering effects while achieving comprehensive UV spectrum coverage
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 doped ZnO particles effectively block UV light across a broader spectrum without causing whitening, enhancing sunscreen performance while maintaining a clear appearance.
Implementation Method 1
modifying the band gap of a ZnO composition via the incorporation of one or more dopants into the composition
Implementation Method 2
increasing absorption across the UV spectrum (280-400 nm) while minimizing scattering effects
Implementation Method 3
The doped ZnO particles effectively block UV light across a broader spectrum without causing whitening
Implementation Method 4
minimizing scattering effects by adjusting the band gap and introducing additional electronic states
Data Source
AI summary
Zinc oxide compositions as well as techniques for doping ZnO particles for sunscreen applications are provided herein. A method includes selecting one or more dopants to be incorporated into one or more zinc oxide particles in a sunscreen composition, wherein said selecting is based on one or more optical properties associated with each of the dopants, and incorporating the selected dopants into the zinc oxide particles to create the sunscreen composition.