Sapphire Sensor Pressure Temperature Compensation
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Solution Overview
Problem
Current pressure sensors face challenges in high-temperature and harsh environments due to material creep, diffusion of foreign species, and thermal expansion mismatches, leading to instability and unreliability in measurements.
Innovation Solution
A pressure and temperature sensor system utilizing a hermetically sealed single-crystal sapphire Fabry-Perot cavity with direct sapphire-to-sapphire bonding, eliminating foreign materials and thermal expansion issues, and incorporating an optical fiber for interrogation, allowing for accurate and stable measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous materials (glasses) are used for sensor construction, then manufacturing ease and cost are improved, but long-term stability deteriorates due to creep under high pressure and diffusion of foreign species at elevated temperatures
Solution Approach 1:
The patent changes the material parameter from amorphous (glass) to crystalline (sapphire) structure. This fundamental material parameter change transforms the sensor's behavior under stress and temperature, eliminating creep and diffusion issues while maintaining manufacturing feasibility through direct bonding techniques.
Solution Approach 2:
The patent employs composite construction by directly bonding sapphire crystals to form a hermetically sealed cavity structure. This composite approach combines the advantages of crystalline materials (stability) with engineered bonding interfaces to achieve both reliability and manufacturability.
2Reliability
If sapphire-to-sapphire direct bonding is used, then long-term stability and high-temperature operation capability are improved, but manufacturing complexity increases due to the bonding process requirements
Solution Approach 1:
The patent applies preliminary action by performing pre-bonding at lower temperatures (around 200°C) before the final high-temperature annealing step. This staged approach simplifies the manufacturing process by breaking down the complex bonding operation into manageable sequential steps, reducing overall manufacturing complexity while maintaining the hermetic seal integrity.
3Ease of manufacture
If foreign materials are introduced in the bonding process, then ease of manufacture is improved, but measurement precision deteriorates due to thermal expansion mismatch and stress variations
Solution Approach 1:
The patent extracts and removes foreign bonding materials from the system entirely. By using direct sapphire-to-sapphire bonding without intermediate adhesives or sealants, the patent eliminates the source of thermal expansion mismatch and stress variations that would compromise measurement precision, while the bonding process remains manufacturable through controlled thermal fields.
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 provides long-term stability and high-temperature operation capability with minimal material creep and foreign material diffusion, enabling accurate simultaneous measurement of pressure and temperature.
Implementation Method 1
an optical fiber that may conduct light reflected off of a surface of the diaphragm
Implementation Method 2
a hermetically sealed single-crystal sapphire Fabry-Perot cavity with direct sapphire-to-sapphire bonding
Data Source
AI summary
A system for measuring pressure, temperature or both includes a diaphragm that responds to a change in temperature or pressure, and a base connected to the diaphragm that has a sapphire element. Between the diaphragm and the base is a cavity. An optical fiber that conducts light reflected off of a surface of the diaphragm is adjacent the cavity. An interrogator is used for detecting a deflection of the diaphragm based on at least two reflected light signals having similar wavelengths and coherence lengths. A quadrature phase detection unit demodulates signals received by the interrogator.