Phosphorous Glass with Silver Ion Antimicrobial Efficacy
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Solution Overview
Problem
Current antimicrobial glasses with silver ions exhibit reduced efficacy at ambient conditions, such as low relative humidity and room temperature, necessitating the development of a glass with enhanced antimicrobial properties that maintain effectiveness in these environments.
Innovation Solution
A chemically strengthened glass composition with a specific range of SiO2, Al2O3, and alkali metal oxides, combined with a 2-step ion exchange process incorporating silver ions, to create a surface concentration of Ag+ ions that maintains antimicrobial activity at ambient conditions without compromising compressive stress or transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver ions are used to impart antimicrobial properties to glass, then antimicrobial activity is improved, but efficacy decreases at ambient conditions (low humidity and room temperature)
Solution Approach 1:
The patent modifies the glass composition by incorporating phosphorous (P2O5) as a key component, which changes the chemical parameters of the glass matrix. This compositional change enables the glass to maintain silver ion release and antimicrobial efficacy at ambient conditions, directly addressing the limitation of conventional silver-containing glasses that lose effectiveness at room temperature and low humidity.
Solution Approach 2:
The invention creates a composite material system combining phosphorous-containing glass matrix with silver ions. The phosphorous-modified glass structure serves as a carrier that enhances the stability and controlled release of silver ions, creating a composite system that maintains antimicrobial activity across varying environmental conditions including ambient temperature and humidity.
2Reliability
If 2-step ion exchange process is used to increase silver ion concentration at surface, then antimicrobial activity is improved, but compressive stress may be compromised
Solution Approach 1:
The ion exchange process is divided into two distinct steps: first exchanging alkali metal ions to establish baseline compressive stress, then exchanging silver ions to achieve antimicrobial functionality. This segmentation allows independent optimization of each property - the first step maximizes compressive stress while the second step introduces silver ions with controlled penetration depth, preventing compromise of mechanical strength.
Solution Approach 2:
The 2-step ion exchange process creates local quality differentiation in the glass surface. The first ion exchange step creates a compressed surface layer for mechanical strength, while the second step introduces silver ions primarily in the outermost surface region. This local concentration of silver ions at the surface provides antimicrobial activity without significantly affecting the deeper compressive stress layer that provides mechanical strength.
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 glass achieves significant antimicrobial activity, with Log Kill values of at least 1.0 at room temperature and low humidity, while maintaining strength and transparency, and the 2-step ion exchange method ensures a shallow silver ion penetration to maximize surface concentration without affecting compressive stress.
Implementation Method 1
a 2-step ion exchange process incorporating silver ions, to create a surface concentration of Ag+ ions
Implementation Method 2
A chemically strengthened glass composition with a specific range of SiO2, Al2O3, and alkali metal oxides
Data Source
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AI summary
A strengthened antimicrobial glass including greater from about 50.0 mol.% to about 65.0 mol.% SiO2, about 14.0 mol.% to about 22.0 mol.% A12O3, about 14.0 mol.% to about 22.0 mol.% R2O, wherein R is an alkali metal, and about 4.0 mol.% to 10.0 mol.% P2O5. The glass may have a compressive stress layer having a thickness of greater than or equal to about 20 μηι to less than or equal to about 60 μm and having a compressive stress of greater than or equal to about 700 MPa. The glass may have an antimicrobial activity greater than or equal to about 1.0 log kill at about 23 °C and about 40.0% relative humidity. A method for making the glass may include obtaining a glass article, strengthening the glass article by contact with a first ion-exchange liquid, and contacting the glass article with second ion- exchange liquid comprising an antimicrobial agent.