Antimicrobial Foam with Embedded Silver Nanoparticles
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Solution Overview
Problem
Existing antimicrobial foams that incorporate silver as a coating tend to lose their efficacy over time due to the silver washing off the substrate, leading to a short duration of antibacterial action.
Innovation Solution
Incorporating silver nanoparticles into the open-cell foam matrix, which are embedded before the foam sets, ensuring they cannot be washed out and providing a larger surface area for activation in aqueous environments, thereby maintaining antimicrobial properties over multiple uses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver is applied as a coating to the foam substrate, then antimicrobial properties are provided, but the silver washing off the substrate over time leading to loss of efficacy
Solution Approach 1:
The patent combines silver nanoparticles with the foam matrix through incorporation during manufacturing, creating a unified composite structure where the silver is an integral part of the foam rather than a separate coating. This merging prevents the silver from washing off while maintaining its antimicrobial properties throughout the foam's service life.
Solution Approach 2:
The patent creates a composite material consisting of foam matrix combined with silver nanoparticles. The silver nanoparticles are dispersed throughout the foam structure, forming a heterogeneous composite where the foam provides structural integrity and the silver provides antimicrobial activity. This composite approach ensures the silver remains embedded and does not wash off.
2Reliability
If silver nanoparticles are incorporated into the foam matrix before setting, then the silver cannot be washed out and antimicrobial properties are maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The patent incorporates silver nanoparticles into the foam matrix during the foam formation process, specifically before the foam sets. This preliminary action ensures the silver is embedded in the matrix structure as it forms, preventing subsequent washing off. The silver nanoparticles are added to the foam components prior to curing, allowing them to become an integral part of the foam structure.
3Reliability
If silver is used as an antimicrobial agent, then broad spectrum antimicrobial activity is achieved, but silver presents toxicity concerns toward humans and animals
Solution Approach 1:
The patent applies silver nanoparticles locally within the foam matrix at controlled concentrations, creating a localized antimicrobial effect at the point of contact with microorganisms. The silver is embedded within the foam structure rather than being applied as a bulk coating, concentrating the antimicrobial activity where needed while minimizing overall silver exposure to humans and animals.
Solution Approach 2:
The patent changes the physical form of silver from bulk material to nanoparticles, significantly altering its properties. The nanoparticle form increases surface area to volume ratio, enhancing antimicrobial effectiveness while allowing reduced total silver content. This parameter change (particle size) maintains antimicrobial efficacy while reducing potential toxicity concerns.
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 antimicrobial foam retains its effectiveness for an extended period, with silver nanoparticles releasing ions that deactivate microorganisms, demonstrating a 99.9% reduction in microbial activity even after repeated uses, outperforming foams with zeolite particles in terms of longevity.
Implementation Method 1
silver nanoparticles releasing ions that deactivate microorganisms
Implementation Method 2
silver is recognized as an elemental material that presents low toxicity toward humans and animals. However, silver presents a significant toxicity to over six hundred species of bacteria, fungi, and viruses
Data Source
AI summary
An antimicrobial foam includes an open-cell foam in a foam matrix defining a plurality of interconnected bubbles therein. Silver nanoparticles are suspended within the foam matrix. The foam matrix may be made from polyether polyurethane, polyester polyurethane, polycarbonate, thermoplastic olefin, thermoplastic elastomer, and thermoplastic polyurethane. The silver nanoparticles may have an average size between about 5 and 100 nanometers. The silver nanoparticles may be incorporated into the foam matrix in a concentration of between about 0.01 weight-% and about 0.20 weight-%. A method of manufacture of the foam also is described.