Self-Diagnostic Resin Composites for Fluorescent Crack Detection
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Solution Overview
Problem
Current non-destructive testing methods for composite materials, such as those used in the aerospace industry, require complex equipment, high skill levels, and often compromise the physical properties of the materials due to the need for large reporting systems or bulk changes to the polymer backbone, making it difficult to detect microscopic damages and stress without altering the material's integrity.
Innovation Solution
A ternary complex comprising Cucurbituril[8], a fluorescent compound, and a quencher compound, which forms a stable complex in the polymer matrix and selectively dissociates under mechanical stress, allowing for fluorescence-based detection of micro-fractures and high strain areas without altering the material's properties, using a low concentration of 10−6 mol kg−1 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If current non-destructive testing methods (X-ray, lock in thermography, pulse echo ultrasounds) are used to detect defects, then defect detection capability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The composite material incorporates self-diagnostic capabilities through embedded fluorescent probes that automatically detect and report their own structural integrity status. The material serves its own inspection function by emitting fluorescence signals in response to mechanical stress, eliminating the need for external complex monitoring equipment.
Solution Approach 2:
The patent replaces complex mechanical and electronic testing equipment (X-ray machines, ultrasound devices, thermography systems) with a simple chemical-optical system based on fluorescent probes. The detection mechanism transitions from sophisticated instrumental analysis to straightforward optical observation of fluorescence emission.
2Measurement precision
If a large amount of reporting system (>=10%) is incorporated into the polymer to enable self-diagnostic properties, then defect detection sensitivity is improved, but the physical properties of the polymer are compromised
Solution Approach 1:
The patent dramatically reduces the concentration of reporting molecules from >=10% to approximately 10^-6 mol kg^-1 (micromolar range). This parameter change enables sufficient detection sensitivity through the high quantum yield of fluorescence while maintaining the polymer's physical properties, as the trace amounts of probes do not interfere with the polymer matrix structure.
Solution Approach 2:
The patent introduces Cucurbituril[8] as a host molecule that forms ternary complexes with fluorescent compounds and quenchers. This intermediary enables the reporting mechanism to function at extremely low concentrations by amplifying the signal through complex formation and dissociation, allowing sensitive detection without compromising polymer properties.
3Difficulty of detecting and measuring
If bulk changes to the polymer backbone are made to achieve self-diagnostic properties, then defect detection capability is improved, but the material's original properties are altered
Solution Approach 1:
The patent extracts the self-diagnostic function from the polymer backbone itself and separates it into independent, incorporated probe molecules. The fluorescent probes, Cucurbituril[8] complexes, and quenchers act as discrete additive components rather than modifications to the polymer chain, allowing the polymer to retain its original structure and properties while gaining diagnostic capabilities.
4Reliability
If conventional reporting systems are used in composite materials, then defect detection is enabled, but the material properties are altered and complex equipment is required
Solution Approach 1:
The composite material incorporates self-diagnostic capabilities through embedded fluorescent probes that automatically detect and report their own structural integrity status. The material serves its own inspection function by emitting fluorescence signals in response to mechanical stress, eliminating the need for external complex monitoring equipment.
Solution Approach 2:
The patent utilizes fluorescence emission (optical property change) as the reporting mechanism. When Cucurbituril[8] complexes dissociate in response to mechanical stress, the quenched fluorescent compounds emit light, providing a visual/optical signal that indicates material degradation. This color/optical change provides intuitive safety monitoring without complex instrumentation.
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
This solution provides a non-invasive, sensitive tool for monitoring structural elements with hand-held equipment, offering excellent contrast between affected and unaffected regions, allowing for the incorporation of self-diagnostic capabilities into commercial resins like epoxy without compromising their bulk properties.
Implementation Method 1
a fluorescent compound having an emission at wavelength above 400 nm
Implementation Method 2
Cucurbiturils are a family of versatile host molecules that have been shown to form ternary complexes that can quench fluorescent molecules on binding with an additional guest
Implementation Method 3
ternary complexes that can quench fluorescent molecules on binding with an additional guest. The fluorescence reappears on dissociation of the complex
Data Source
AI summary
The present invention relates to the sector of self-diagnostic composite materials. In particular, the invention presents an agent, which can be cross-linked together with a curing agent in a matrix, e.g. an epoxy resin, and fibres, e.g., carbon fibre, in order to obtain a composite material containing a reporting probe capable of detecting stress, fatigue and microscopic cracks in the material with high spatial resolution and sensitivity.