Tungsten Oxide Antibacterial Material for Low-Light Environments
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Solution Overview
Problem
Conventional antibacterial agents, particularly those using titanium oxide photocatalysts, exhibit insufficient performance in indoor environments with low illuminance and require special light conditions, limiting their application in everyday products such as stationery and kitchen goods.
Innovation Solution
Development of antibacterial materials incorporating tungsten oxide microparticles and complexes, which demonstrate effective antibacterial activity against various bacteria without the need for special light, by optimizing particle size, specific surface area, and crystalline structure to ensure performance in low-light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium oxide photocatalyst is used as antibacterial agent, then antibacterial performance can be achieved under ultraviolet light, but performance is insufficient in indoor environment with low ultraviolet light
Solution Approach 1:
The patent modifies the bandgap parameter of titanium oxide by doping with nitrogen or sulfur, or by adding visible light-absorbing pigments, enabling the photocatalyst to absorb visible light instead of only ultraviolet light. This parameter change allows the antibacterial agent to function effectively under indoor lighting conditions with lower ultraviolet content.
Solution Approach 2:
The patent creates composite materials by combining titanium oxide with visible light-absorbing pigments or doping titanium oxide with nitrogen/sulfur. This composite approach enables the material to utilize both ultraviolet and visible light spectrum, expanding its operational range to include indoor environments with insufficient ultraviolet light.
2Reliability
If visible light-responsive photocatalyst with platinum compound impregnated or nitrogen/sulfur doped titanium oxide is used, then performance under visible light is improved, but excitation wavelength range is narrow and performance under general indoor lighting is insufficient
Solution Approach 1:
The patent develops photocatalytic compositions that can respond to multiple wavelengths of light including ultraviolet, visible, and near-infrared regions. By incorporating broad-spectrum light absorbers or using composite structures, the antibacterial agent achieves universal responsiveness across different lighting conditions, making it adaptable to various indoor environments with different spectral compositions.
3Adaptability or versatility
If antibacterial agent based on photocatalyst is used in low illuminance environment, then application in indoor products is enabled, but sufficient light irradiation to excite photocatalyst cannot be obtained
Solution Approach 1:
The patent reduces the energy threshold for photocatalyst excitation by modifying the bandgap structure through doping or composite formation. This allows the photocatalyst to absorb lower-energy photons from visible and near-infrared light sources, enabling effective operation in low-illuminance indoor environments where sufficient ultraviolet energy is unavailable.
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 tungsten oxide-based antibacterial materials achieve significant reductions in bacterial viable cell counts, maintaining high antibacterial performance in both illuminated and dark environments, making them suitable for a wide range of indoor applications.
Implementation Method 1
tungsten oxide has a bandgap smaller than that of titanium oxide and therefore attracts attention as a material capable of providing a photocatalytic action by visible light
Data Source
AI summary
In one embodiment, an antibacterial material includes at least one microparticles selected from tungsten oxide microparticles and tungsten oxide complex microparticles. The microparticles, which have undergone a test to evaluate viable cell count by inoculating in a test piece, to which the microparticles are adhered in a range of 0.02 mg/cm2 or more and 40 mg/cm2 or less, at least one bacterium selected from among Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and enterohemorrhagic Escherichia coli, and storing for 24 hours, have an antibacterial activity value R of 0.1 or more expressed by the following: R=log(B1/C1) where, B1 denotes an average value (number) of viable cell count after storing an untreated test piece for 24 hours, and C1 denotes an average value (number) of viable cell count after storing the test piece on which the microparticles are coated for 24 hours.