Visible-Light Antimicrobial Coating for Low-Temperature Surfaces
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Solution Overview
Problem
Existing antimicrobial coatings are time-consuming to produce, unstable, require UV light for activation, and are not suitable for substrates with low temperature stability, limiting their application in indoor environments.
Innovation Solution
A process involving the mixing of a chelating agent with titanium alkoxide and fluoroacetic acid, followed by addition of an aqueous solution, to create a transparent, visible light-activated antimicrobial coating that is stable at high temperatures and can be applied to various substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photocatalytically active pigments such as titanium dioxide are used for antimicrobial coating, then antimicrobial effectiveness is improved, but the coating requires UV light activation which is not readily available in indoor environments
Solution Approach 1:
The patent modifies the optical properties of titanium dioxide by doping with metal elements (copper, silver, zinc) to change the activation wavelength from UV to visible light range. This parameter change enables the coating to be activated by ambient indoor lighting conditions rather than requiring UV light, thereby resolving the contradiction between maintaining antimicrobial effectiveness and adapting to indoor illumination conditions.
2Reliability
If existing sol-gel processes are used to prepare antimicrobial coating, then coating formation is achieved, but the process is time-consuming and involves multiple processing steps
Solution Approach 1:
The patent combines multiple functions into a single sol formulation: the metal-doped titanium dioxide precursor, the chelating agent for stability, and the visible light activation capability are all integrated into one coating solution. This merging of functions into a unified sol-gel system reduces the number of separate processing steps required while maintaining coating stability and effectiveness.
Solution Approach 2:
The patent performs preliminary doping of titanium dioxide with metal elements during the sol preparation stage, before coating application. This preliminary action incorporates the visible light activation capability and antimicrobial properties into the base material itself, eliminating the need for subsequent complex processing steps to achieve these functions.
3Stability of the object's composition
If high temperature processing is used for coating synthesis, then coating stability is improved, but glass substrates soften and lose morphological properties at temperatures over 700°C
Solution Approach 1:
The patent changes the processing temperature parameter from high temperature (1000°C for ceramics) to low temperature (below 700°C for glass) by modifying the sol-gel chemistry. The metal-doped titania sol is formulated to undergo hydrolysis and condensation reactions at lower temperatures, enabling coating formation and stabilization without exceeding glass softening points, thus resolving the contradiction between coating stability and substrate temperature tolerance.
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 process results in a thin, homogeneous, and effective antimicrobial coating that operates under visible light conditions, suitable for indoor use and stable up to 1350°C, providing broad-spectrum pathogen reduction.
Implementation Method 1
mixing a chelating agent with titanium alkoxide and fluoroacetic acid, followed by addition of an aqueous solution
Implementation Method 2
visible light-activated antimicrobial coating that is stable at high temperatures
Implementation Method 3
TiO2 reacts with light of appropriate wavelength resulting in the activation of TiO2, and creates a number of reactive oxygen species (ROS) such as hydroxyl radicals and superoxide anions
Data Source
AI summary
A process for the preparation of an antimicrobial coating solution includes the steps of: (i) mixing a chelating agent with titanium alkoxide and fluoroacetic acid; and (ii) adding an aqueous solution to the mixture from step (i). The antimicrobial coating is visible light activated and can be applied to surfaces and optionally heat treated to form a transparent layer on the surface.