Miniature Fiber-Optic Pressure Sensor Hydroxide Bonding
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Solution Overview
Problem
Conventional diaphragm-based fiber-optic FP pressure sensors face challenges with large size, low structure stability, and limited application in extreme environments due to inadequate bonding methods, which result in poor thermal stability, low precision alignment, and reduced sensitivity.
Innovation Solution
The use of hydroxide catalysis bonding technology for assembling the diaphragm-based fiber-optic sensor, combining arc welding and hydroxide catalysis bonding to create a miniature sensor with high-precision alignment and a thin, strong bonding layer, eliminating the need for organic materials and high-temperature processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding methods (epoxy resin, laser welding, arc welding) are used to fix the diaphragm, then the assembly process can be completed, but the thermal stability is poor and the structure stability is low
Solution Approach 1:
The patent changes the bonding parameters by using hydroxide catalysis bonding at room temperature instead of high-temperature methods like laser welding or arc welding. This chemical bonding approach creates a stable bond without thermal damage, improving both structural integrity and thermal stability of the sensor assembly.
Solution Approach 2:
The patent replaces mechanical/thermal bonding methods (laser welding, arc welding, epoxy resin) with a chemical bonding mechanism (hydroxide catalysis bonding). This substitution eliminates the thermal effects and mechanical stress associated with conventional methods, resulting in better thermal stability and structural reliability.
2Reliability
If the optical fiber is nested in a collimation capillary tube to form the sensor, then the FP interferometer can be formed, but the sensor size becomes large (diameter of a few millimeters)
Solution Approach 1:
The patent extracts and eliminates the collimation capillary tube from the sensor structure. By directly bonding the diaphragm to the optical fiber tip without the intermediate capillary tube, the sensor achieves miniaturization while maintaining its FP interferometer functionality and measurement reliability.
Solution Approach 2:
The patent segments the sensor structure into minimal essential components: the optical fiber tip directly bonded to the diaphragm. This segmentation removes unnecessary intermediate structures (capillary tube) and creates a compact integrated sensor with volume reduced to cubic millimeter scale.
3Volume of moving object
If the diaphragm diameter is reduced to match the optical fiber diameter for miniaturization, then the sensor volume decreases, but the requirements for alignment and fixation operations become extremely high
Solution Approach 1:
The hydroxide catalysis bonding process provides self-alignment capabilities through chemical adhesion that can accommodate minor misalignments. The bonding chemistry creates strong adhesion even with the extremely tight alignment requirements imposed by miniaturized diaphragms matching optical fiber dimensions.
Solution Approach 2:
The hydroxide catalysis bonding solution acts as an intermediary that facilitates precise bonding of miniaturized components. This chemical mediator enables reliable fixation of the ultra-thin diaphragm to the optical fiber tip despite the extremely high alignment precision requirements, by providing a bonding mechanism that is more tolerant than mechanical or thermal methods.
4Ease of manufacture
If epoxy resin and organic adhesives are used for diaphragm fixation, then the assembly is simple, but the adhesives are not resistant to high temperature and are easy to creep under long-term stress
Solution Approach 1:
The patent replaces organic adhesive bonding with hydroxide catalysis chemical bonding. This substitution eliminates the temperature resistance and creep issues associated with organic adhesives while maintaining assembly simplicity through a straightforward chemical bonding process that cures at room temperature.
Solution Approach 2:
The patent uses inorganic bonding materials (hydroxide catalysis bonding solution) instead of organic adhesives. This material substitution provides high-temperature resistance and long-term stress resistance while maintaining the ease of manufacture through a simple bonding process that does not require high-temperature equipment.
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 approach enables the fabrication of a compact, high-sensitivity, and stable miniature pressure sensor capable of withstanding extreme conditions, including high temperatures and pressures, with improved long-term stability and expanded application in harsh environments.
Implementation Method 1
the pressure sensing diaphragm 3 is bonded to the endface of the hollow-core optical fiber 4 by hydroxide catalysis bonding
Implementation Method 2
the optical fiber 1 and the hollow-core optical fiber 4 have the same diameter, the two are spliced by arc welding
Implementation Method 3
Under the action of ambient pressure, the diaphragm is elastically deformed, which leads to the change in the distance between the endface of the optical fiber and the inner surface of the pressure sensing diaphragm
Data Source
AI summary
A miniature diaphragm-based fiber-optic tip FP pressure sensor, and fabrication method and application thereof. A miniature diaphragm-based fiber-optic tip FP pressure sensor includes an optical fiber, a hollow-core optical fiber, and a pressure sensing diaphragm, wherein the optical fiber and the hollow-core optical fiber have the same diameter, the two are spliced by arc welding; and the pressure sensing diaphragm is bonded to the endface of the hollow-core optical fiber by hydroxide catalysis bonding. The FP pressure sensor can not only realize the all-silica structure of a sensor, but also make the joint of each component free of organic polymer, and has extremely high long-term stability and thermal stability. Meanwhile, by a fabrication method of the miniature diaphragm-based fiber-optic tip FP pressure sensor, the application range and service life of the sensor are increased, and fabrication costs are reduced.