Tunable Rare Earth Metal-Organic Frameworks for Multiplexed Optical Tags
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Solution Overview
Problem
Existing optical tags suffer from monochromatic emission bands, complex synthesis methods, amorphous physical structures, and the need for specialized interrogation equipment, limiting their effectiveness in secure, multi-tiered screening and real-life implementation.
Innovation Solution
Development of tunable rare earth metal-organic frameworks (REMOFs) with polynuclear metal clusters interconnected by carboxylic acid-based linkers, incorporating high-energy donor and lower-energy acceptor rare earths, and optionally optically inactive rare earths to modulate energy transfer and luminescence lifetimes, enabling facile synthesis and secure, multiplexed encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing optical tag materials are used, then monochromatic emission is achieved, but multi-tiered screening capability deteriorates
Solution Approach 1:
The patent uses composite materials by combining multiple rare earth metal ions (Eu³⁺, Tb³⁺, Dy³⁺, Er³⁺, Tm³⁺, Nd³⁺, Sm³⁺, Pr³⁺, Ho³⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺) within a single metal-organic framework structure. This composite approach enables the material to exhibit multiple emission bands simultaneously, providing multi-tiered screening capability while maintaining a unified material system rather than requiring multiple separate materials.
Solution Approach 2:
The patent changes the compositional parameters of the optical tag by systematically varying the types and ratios of rare earth metal ions incorporated into the framework. By adjusting these parameters, the material can be tuned to exhibit specific emission characteristics suitable for different screening tiers, transforming a single-material system into a multi-functional platform.
2Reliability
If complex synthesis methods are used, then material performance is improved, but manufacturing efficiency deteriorates
Solution Approach 1:
The patent segments the synthesis process into a modular one-pot approach where all components (metal salts, organic linkers, and rare earth ion solutions) are combined simultaneously in a single reaction vessel. This segmentation of the synthesis strategy eliminates multi-step procedures while maintaining control over the incorporation of multiple rare earth ions, thereby improving manufacturing efficiency without sacrificing material performance.
Solution Approach 2:
The patent creates a universal synthesis platform using the MOF-5 framework that can accommodate various combinations of rare earth metal ions through a single standardized procedure. This multi-functional approach allows the same base framework and synthesis protocol to produce different optical tag compositions, significantly improving manufacturing efficiency and scalability.
3Adaptability or versatility
If amorphous physical structure is used, then material flexibility is improved, but characterization and manipulation difficulty increases
Solution Approach 1:
The patent applies local quality by maintaining the crystalline order of the MOF-5 framework at the macroscopic structural level while incorporating rare earth ions at the local atomic sites within the metal clusters. This approach preserves the beneficial crystalline characteristics (facilitating characterization) while allowing local compositional variation (providing flexibility for different optical properties).
Solution Approach 2:
The patent creates a composite structure where the crystalline MOF-5 framework serves as the ordered host matrix, and rare earth metal ions are embedded as functional guests within the framework's metal coordination sites. This composite architecture combines the structural advantages of crystalline materials (ease of characterization) with the optical versatility of rare earth ions.
4Measurement precision
If highly specialized interrogation equipment is used, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent designs optical tags that exhibit distinct color emission changes across multiple wavelengths when excited by UV light. These visible color changes can be detected by the naked eye or simple colorimeters, eliminating the need for specialized spectroscopic equipment while maintaining sufficient precision for authentication purposes through the unique multi-color emission patterns.
Solution Approach 2:
The patent creates optical tags with inherently stable and distinct optical signatures that can be interrogated using inexpensive, widely available equipment. This approach replaces expensive, specialized instrumentation with simple, accessible tools, making the authentication system easier to operate and more widely deployable.
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
Facilitates secure, multiplexed encoding with tunable emission spectra and lifetimes, accessible for widespread use and resistant to counterfeiting, using basic lab equipment for interrogation.
Implementation Method 1
the rare earths are arranged in polynuclear metal clusters interconnected by carboxylic acid-based linkers... incorporating high-energy donor and lower-energy acceptor rare earths
Implementation Method 2
at least one optically inactive higher-energy rare earth that modulates the distance between the at least one high-energy donor rare earth and the at least one lower-energy acceptor rare earth in the polynuclear clusters
Implementation Method 3
tunable rare earth metal-organic frameworks (REMOFs) with polynuclear metal clusters... enabling facile synthesis and secure, multiplexed encoding
Data Source
AI summary
The invention provides a powerful design strategy towards next-generation, multiplexed, lifetime-encoded tags via engineering intermetallic energy transfer in heterometallic metal-organic frameworks based on nonanuclear metal clusters. Precise manipulation of the luminescence decay dynamics over a wide microsecond regime can be achieved owing to the control over metal ordering in these systems. As an example of the invention, a novel, dynamic double encoding method that uses the braille alphabet was achieved by incorporating the materials into photocurable inks patterned on glass and interrogated via digital high-speed imaging. The facile synthesis and interrogation of these heterometallic metal-organic frameworks having complex and tunable optical properties enables next-generation, multiplexed optical tags.