Gold Nanorod Ink Composition for Invisible NIR Image Reading
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Solution Overview
Problem
Existing inks containing gold nanorods for invisible printing face issues with storage stability and a trade-off between invisibility in the visible light region and readability in the near-infrared region, as well as the need for improved usability.
Innovation Solution
An ink formulation using gold nanorods with a specific aspect ratio distribution (average µ of 6.0 to 13.0 and standard deviation σ of 0.5 to 4.5) and surfactants with HLB values of 15 or less, such as acetylene glycol-based and silicone surfactants, stabilizes the dispersion and enhances optical absorption in the near-infrared region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ink compositions are used for inkjet printing, then the ink can be applied to paper, but the printed image cannot withstand water or external force and the text or image becomes illegible
Solution Approach 1:
The patent applies composite materials by combining multiple components in the ink formulation: colorant, binder resin, solvent, and specifically added microcapsules containing flavoring substance or fragrance. This composite structure creates an ink that is both durable and provides enhanced functionality. The microcapsules are embedded within the ink matrix, forming a composite material system that maintains structural integrity while adding protective and functional properties.
Solution Approach 2:
The patent applies local quality by incorporating microcapsules with specific functional properties (flavoring substance or fragrance) into specific regions of the ink composition. These microcapsules are distributed throughout the ink but remain distinct local entities that provide localized functionality. The ink thus has different local properties: the base ink provides color and adhesion, while the microcapsules provide sensory enhancement and protective functions.
2Adaptability or versatility
If existing inks are used, then printing can be performed, but the printed material lacks resistance to water and physical force making it unsuitable for practical applications
Solution Approach 1:
The patent applies parameter changes by modifying the chemical and physical parameters of the ink system through the addition of microcapsules. The microcapsules change parameters such as water resistance, mechanical strength, and functional properties (flavor release, fragrance emission). This allows the ink to adapt to various application requirements including waterproof needs, durability requirements, and sensory enhancement applications.
3Quantity of substance
If standard ink formulations are applied, then the printing process can proceed, but the resulting print lacks functional enhancement and durability for real-world use
Solution Approach 1:
The patent applies the intermediary principle by using microcapsules as mediator elements between the ink and the environment. These microcapsules act as intermediaries that protect the core substance (flavoring or fragrance) from degradation while enabling controlled release. They mediate between the printed material and external factors such as water, physical force, and environmental conditions, providing both protection and functional enhancement.
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 ink achieves excellent invisibility in the visible light region and high readability in the near-infrared region while maintaining stable storage properties, allowing for effective image formation and reading with near-infrared sensors.
Implementation Method 1
the microcapsules are designed to rupture when the printed material is subjected to water or external force
Data Source
Figure 1
AI summary
An ink provided contains water, gold nanorods, and at least one surfactant selected from the group consisting of acetylene glycol-based surfactants with an HLB value of 15 or less and silicone surfactants with an HLB value of 15 or less. When the aspect ratio distribution of the gold nanorods contained in the ink is measured, the aspect ratio distribution has an average µ of 6.0 to 13.0 with a standard deviation σ of 0.5 to 4.5.