Optical Sensor with Protective Coating for Oil Monitoring
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Solution Overview
Problem
Existing optical sensors for monitoring oil concentration in cleaning liquids used in machining processes are not suitable for long-term use due to corrosion from organic solvents or acidic/basic solutions and struggle to detect low concentrations of oil, as they require frequent distillation and have sensitivity issues with vibration and light loss.
Innovation Solution
An optical sensor with a removed cladding layer and a protective material coating on the exposed core layer, combined with an optical waveguide design that measures evanescent light transmittance, allowing for real-time monitoring of oil concentration in cleaning liquids over extended periods without sample drawing, using a light source and receiving device to calculate oil concentration based on light intensity ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical sensor with cladding layer is used to monitor oil concentration, then the sensor structure is complete and chemically resistant, but it cannot detect low concentrations of oil and suffers from light loss reducing sensitivity
Solution Approach 1:
The cladding layer is selectively removed from a specific region of the optical fiber to create an exposed core region. This extraction allows evanescent light to interact directly with the cleaning liquid, enabling detection of low oil concentrations that would otherwise be undetectable through the intact cladding structure.
Solution Approach 2:
The optical fiber is modified with different properties in different regions: the cladding is removed only in the measurement region while remaining intact in other sections. This local modification enables light interaction with the liquid at the exposed core while maintaining structural integrity and chemical resistance in non-measurement areas.
2Duration of action of stationary object
If the optical sensor operates in cleaning liquids with organic solvents or acidic/basic solutions over long periods, then continuous monitoring is achieved, but the sensor deteriorates due to corrosion
Solution Approach 1:
A protective coating is applied to the exposed core region of the optical fiber. This thin film layer provides chemical resistance against organic solvents and acidic/basic solutions in the cleaning liquid, protecting the exposed core from corrosion while allowing evanescent light interaction for continuous long-term monitoring.
Solution Approach 2:
The optical sensor combines multiple materials with complementary properties: the optical fiber core for light transmission, the protective coating for chemical resistance, and the cladding layer for structural support. This composite structure enables both durability in harsh cleaning environments and functional performance for oil concentration detection.
3Measurement precision
If bulk light type optical absorption method is used, then a large-scale measuring instrument is required with complex optical system, but it provides reference path comparison capability
Solution Approach 1:
The reference path and measurement path are combined into a single optical fiber structure. The intact cladding sections serve as reference paths while the exposed core section interacts with the liquid for measurement. This merging eliminates the need for separate bulk light paths and complex comparison systems while maintaining measurement accuracy through internal reference comparison.
Solution Approach 2:
The complex mechanical bulk light optical system is replaced with an integrated optical fiber-based evanescent field sensor. The measurement function is achieved through optical field interactions within the fiber itself rather than external bulk light paths, significantly simplifying the overall system while maintaining precision.
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 accurate, long-term monitoring of low oil concentrations in cleaning liquids, improving sensor durability and sensitivity while reducing the need for frequent distillation, thus enhancing operational efficiency.
Implementation Method 1
measuring evanescent light transmittance
Implementation Method 2
measuring a degree of light absorption by the substance, that is, absorbance
Data Source
AI summary
Provided are an optical sensor and an analyzer, including an optical sensor section in which a cladding layer of an optical fiber is removed so as to expose a core layer by a predetermined optical path length, and a protective material is added to a surface of the exposed core layer, the protective material having higher resistance to an organic solvent, base, or acid than that of the cladding layer; a light source device that causes light to enter one end of the optical fiber; a light receiving device that receives transmitted light emitted from another end of the optical fiber; and a control device that controls the light source device and the light receiving device to measure optical transmittance in the optical sensor based on a ratio of intensity of the light emitted from the light source device to intensity of the light received by the light receiving device.