Ratiometric Fiber Optic Dissolved Oxygen Sensor
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Solution Overview
Problem
Existing optical dissolved oxygen sensors face challenges with stability and accuracy due to influences from light source fluctuations, uneven indicator distribution, and indicator attenuation, particularly in measuring underwater dissolved oxygen concentrations.
Innovation Solution
A ratiometric fiber optic chemical sensor system is developed by depositing a composite sensitive dye on a fiber optic probe, using a specific ratio of ethyl silicate, n-octyltriethoxysilane, Triton X-100, tri(4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride, and 7-amino-4-trifluoromethyl coumarin, which improves homogeneity and stability, and employs a dip-coating process followed by stabilization in a dry environment, utilizing a 405 nm light source for fluorescence excitation and spectral data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fluorescent indicator is used to measure dissolved oxygen concentration, then the measurement process is simple, but the measurement accuracy deteriorates due to light source fluctuations and indicator attenuation
Solution Approach 1:
The patent divides the sensing system into two independent fluorescent indicators with different properties: one whose fluorescence intensity is sensitive to oxygen concentration, and another whose fluorescence intensity is insensitive to oxygen. This segmentation allows the system to separate the measurement signal from interference signals, improving measurement accuracy while maintaining relatively simple device structure
Solution Approach 2:
The patent changes the parameter of fluorescence intensity by using two different fluorescent indicators with distinct fluorescence characteristics. By monitoring the ratio of fluorescence intensities at different wavelengths, the system can eliminate the influence of light source fluctuations and indicator attenuation, thereby improving measurement precision without significantly increasing device complexity
2Reliability
If fluorescent lifetime measurement method is used, then light source influence is eliminated, but the number of available sensitive dyes is limited and fluorescent lifetime may change
Solution Approach 1:
The patent replaces the fluorescent lifetime measurement method with a fluorescence intensity ratio method. Instead of measuring the temporal decay of fluorescence, the system measures the ratio of fluorescence intensities at different wavelengths, which eliminates the limitation of limited sensitive dye availability while maintaining reliability by using oxygen-insensitive reference indicators
3Measurement precision
If uniform indicator distribution is achieved, then measurement accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-mixing the two fluorescent indicators in specific ratios within the polymer matrix before sensor fabrication. This preliminary mixing ensures uniform distribution of indicators throughout the sensing membrane, improving measurement accuracy without requiring complex post-fabrication processing steps
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 system enhances measurement stability and accuracy, reducing the impact of light source fluctuations and indicator attenuation, achieving a high linearity of 98.60% and sensitivity of 0.4682/unit [O2] in dissolved oxygen concentration detection, with improved response time and repeatability.
Implementation Method 1
employing a dip-coating process followed by stabilization in a dry environment, utilizing a 405 nm light source for fluorescence excitation and spectral data processing
Implementation Method 2
adding guaranteed reagent absolute ethyl alcohol and hydrogen chloride with a concentration of 0.1 M to a sol solution to catalyze a hydrolysis reaction of organically modified silicate
Data Source
AI summary
The present disclosure discloses a manufacturing method of an optical fiber chemical ratiometric sensor measurement system for measuring underwater dissolved oxygen concentration. The manufacturing method includes the steps of firstly, preparing a carrier substrate to obtain a solution A; then, preparing an oxygen sensitive dye to obtain a solution B; preparing a reference dye to obtain a solution C; mixing the solution A, the solution B and the solution C according to a ratio of 2:1:1 to obtain a composite sensitive dye; depositing the composite sensitive dye on one end face of a sensing optical fiber to prepare a fiber optic probe; establishing the optical fiber chemical ratiometric sensor measurement system, receiving the optical signal by a spectrometer as a fluorescence spectrum, and finally saving and processing fluorescence spectral data by computer software.