Luminescence Material Identification via Decay Constants
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Solution Overview
Problem
Current methods for identifying and sorting plastics materials using luminescence are hindered by factors such as discoloration, cloudiness, and soiling, which affect the optical characteristics, and require a wide variety of excitation regimes to distinguish different markers, making uniform identification challenging.
Innovation Solution
A method involving the incorporation or application of luminescent substances and analyzing their luminescence behavior over time, with modulated excitation conditions, including time, spectral, and radiation intensity, to determine intensity ratios and decay constants, allowing for relative measurements that are insensitive to interference from additives or soiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If absolute measurements of absorption, reflection or fluorescence at defined wavelengths are used for material identification, then identification can be performed with simple measurement procedures, but the results differ due to foreign substances, pigments, dyes, soiling, use or age affecting optical characteristics
Solution Approach 1:
The patent changes the measurement parameter from absolute intensity values to intensity ratios and decay constants. By measuring the ratio of luminescence intensities at different wavelengths or time points, and by analyzing the temporal decay characteristics of luminescence, the method obtains parameters that are independent of absolute intensity variations caused by foreign substances, pigments, dyes, soiling, use or age, while maintaining simple measurement procedures.
2Adaptability or versatility
If a large number of distinguishable markers are used to sort the variety of plastics materials, then more material types can be identified, but more excitation regimes are required to generate and analyze the markers
Solution Approach 1:
The patent employs time-resolved luminescence measurement that captures the periodic or temporal decay characteristics of luminescence emission. By measuring luminescence intensity at multiple time points after excitation and analyzing decay constants, the method can distinguish different markers using a single excitation regime, thereby reducing the need for multiple excitation conditions while maintaining the ability to identify diverse plastic materials.
Solution Approach 2:
The patent adds the time dimension to luminescence measurement by analyzing the temporal decay characteristics of luminescence emission. Instead of relying solely on spectral information from different excitation wavelengths, the method uses the time-dependent decay behavior of luminescence to differentiate markers, effectively adding another dimension to the identification space without requiring additional excitation regimes.
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
Enables effective identification and sorting of plastics materials by exploiting relative luminescence characteristics, ensuring accurate differentiation regardless of material age or condition, and allows for the use of a variety of luminescent markers with different emission properties.
Implementation Method 1
luminescent substances, whose luminescence emission is a non-linear function of the excitation power, whereas the luminescence emission of other luminescent markers is proportional to the excitation power
Implementation Method 2
fluorescent markers in different concentrations
Data Source
AI summary
The present invention relates to a method of identifying and/or distinguishing materials by means of luminescence, wherein at least one luminescent substance is incorporated into the material and/or applied onto the material and the luminescence behaviour of the substance is analysed after excitation by means of radiation, and the use thereof for identifying and/or sorting and/or recycling and/or authenticating and/or performing a quality check and/or formulation check on materials.