Core-Shell Luminophores for Clear Customs Security Marks
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Solution Overview
Problem
Infrared luminescent materials with low absorption cross sections and low upconversion luminescence intensity are not effective for clearly marking suspicious luggage in customs security checks, making it difficult to recognize and track contraband.
Innovation Solution
Preparation of core-shell luminosphores comprising Ag@TiO2@NaYF4:Yb3+, Er3+ nanoparticles, which are sprayed onto luggage tags to form concealed marks that absorb near-infrared light and emit visible patterns, allowing for identification of the owner and triggering security alerts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional infrared luminescent materials are used for marking luggage, then the marking process is simple, but the absorption cross section is small and upconversion luminescence intensity is low, resulting in unclear luminescent marks
Solution Approach 1:
The patent uses a core-shell structure composite material consisting of Ag core, TiO2 intermediate layer, and NaYF4:Yb3+, Er3+ shell. This composite structure combines the advantages of different materials: Ag provides high absorption cross section for near-infrared light, TiO2 offers photostability and prevents aggregation, while NaYF4:Yb3+, Er3+ provides strong upconversion luminescence. The synergistic effect of these composite materials resolves the contradiction between achieving high luminescence intensity and maintaining material simplicity.
Solution Approach 2:
The patent employs a nested core-shell structure where Ag nanoparticles are enclosed within TiO2 shell, which is further enclosed within NaYF4:Yb3+, Er3+ luminescent shell. This nested configuration allows each layer to perform its specific function while protecting the inner layers, thereby achieving high luminescence intensity through the inner Ag core without exposing it directly, and simultaneously maintaining structural integrity and stability.
2Measurement precision
If high absorption cross section materials are used, then luminescence intensity improves, but the complexity of material preparation and structure increases
Solution Approach 1:
The patent employs a sequential preparation approach where Ag nanoparticles are first synthesized and characterized, then TiO2 shell is grown on Ag surfaces through hydrolysis of titanium isopropoxide, and finally NaYF4:Yb3+, Er3+ luminescent shell is formed through solvothermal method. Each step is optimized and controlled independently, with preliminary characterization at each stage to ensure quality. This preliminary action at each preparation stage ensures the final product achieves high mark recognition clarity while maintaining ease of manufacture through standardized, repeatable processes.
Solution Approach 2:
The patent optimizes various preparation parameters including TiO2 shell thickness (controlled by hydrolysis time and temperature), NaYF4 shell composition (Yb3+ and Er3+ doping ratios), and solvothermal conditions (temperature, time, pH). By systematically adjusting these parameters, the patent achieves the optimal balance between luminescence performance and preparation simplicity, resolving the contradiction between mark recognition clarity and ease of manufacture.
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 core-shell luminosphores provide clear, visible patterns under near-infrared light, enabling effective identification of suspicious luggage and preventing deception, while being water-soluble and dispersible in organic solvents, facilitating intelligent and safe customs clearance.
Implementation Method 1
upconversion luminescence intensity thereof is low, as a result, the luminescent marks are not clear enough to recognize marked susceptible luggage
Implementation Method 2
Ag@TiO2@NaYF4:Yb3+, Er3+ luminescent nanoparticles
Data Source
AI summary
Concealed mark preparation with core-shell luminosphores for customs security check system and application thereof, to address that infrared luminescent materials have not been used in senseless customs clearance field, absorption cross sections of infrared luminescent materials currently available are not big enough, and upconversion luminescence intensity thereof is low, consequently, the luminescent marks are not clear enough to recognize marked abnormal luggage, and provide a following solution: step 1: preparing TiQ2; step 2: preparing Ag@TiO2 composite nanoparticles; step 3: preparing Ag@TiQ2@NaYF4:Yb3+, Er3+ luminescent nanoparticles; step 4: making concealed luggage marks. Ag@TiQ2@NaYF4:Yb3+, Er3+ luminescent nanoparticles according to the present invention has superior luminescent intensity than pure NaYF4:Yb3+, Er3+, and luminescent materials prepared in this method can be disseminated in organic solution such as ethanol and methanol for use in preparing concealed marks to mark susceptible luggage and provides a research direction for senseless, intelligent and safe customs clearance.