Corrosion-Resistant High Temperature Pressure Transducer
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Solution Overview
Problem
Existing high temperature pressure transducers face challenges such as corrosion, complex construction, and limited temperature range due to issues with oil vapor pressure and cement dielectric isolation, leading to unreliable performance and thermal compensation difficulties.
Innovation Solution
A sensor array with a corrosion-resistant metal diaphragm and piezoresistive silicon-on-insulator sensors connected in a bridge configuration, dielectrically isolated from the substrate, which allows for efficient stress distribution and high temperature operation without electrical breakdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thin metallized isolation diaphragm is mounted in front of the sensor and pressure is transmitted by a small volume of oil, then the transducer can operate at high temperatures, but the vapor pressure of the oil increases at high temperatures causing the oil to no longer transmit pressure properly, setting an upper temperature limit
Solution Approach 1:
The patent removes the oil coupling medium from the system entirely. Instead of using oil to transmit pressure from the diaphragm to the sensor, the design directly couples the sensor to the diaphragm through a solid mounting structure, eliminating the temperature-dependent vapor pressure issue that limited operating temperature ranges in previous designs.
Solution Approach 2:
The patent introduces a solid mounting structure as an intermediary between the diaphragm and sensor, replacing the liquid oil mediator. This solid structure provides stable mechanical coupling for pressure transmission without suffering from vapor pressure effects, enabling reliable operation at higher temperatures.
2Ease of manufacture
If individual gauges are affixed to the diaphragm using high temperature cement or glass, then the gauges can be positioned on the diaphragm, but variations in cement thickness cause electrical breakdowns at relatively low temperatures
Solution Approach 1:
The patent replaces the cement-based mechanical bonding method with a direct solid mounting structure that provides both mechanical support and electrical isolation. This eliminates the thickness variation problem inherent in cement applications, preventing electrical breakdowns while maintaining ease of assembly.
Solution Approach 2:
The patent employs a composite mounting structure that integrates mechanical support and electrical isolation functions into a single robust component. This composite approach eliminates the need for separate cement layers, providing consistent thickness and reliable electrical isolation at high temperatures.
3Manufacturing precision
If individual silicon gauges are made long to obtain sufficient resistance, then the gauges exhibit high resistivity, but it becomes difficult to place the gauge in a region of high stress and thermal compensation becomes difficult due to non-linear resistance changes at high temperatures
Solution Approach 1:
The patent applies local quality by positioning sensors at specific locations on the diaphragm where stress characteristics are optimal for measurement. Rather than making gauges long to increase resistance, the design places multiple sensors at strategically chosen locations, allowing each sensor to be short while maintaining high resistance and accurate stress measurement capability.
Solution Approach 2:
The patent changes the approach to achieving sufficient resistance by using multiple short sensors in a bridge configuration rather than one long sensor. This parameter change allows optimal placement in high-stress regions while maintaining sufficient total resistance, and the bridge configuration enables linear thermal compensation through differential measurement.
4Ease of manufacture
If various sensors are interconnected prior to application to the diaphragm, then the sensor array can be pre-assembled, but the structure becomes complex, fragile, and difficult to handle, resulting in dubious quality
Solution Approach 1:
The patent merges the sensor interconnection and diaphragm mounting operations into a single integrated process. The sensor array is interconnected and mounted to the diaphragm as a unified structure, eliminating the need for separate handling of fragile interconnected sensors. This reduces complexity and improves quality while maintaining manufacturing efficiency.
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 solution provides a stable and reliable pressure transducer capable of operating at high temperatures with reduced self-heating and improved thermal compensation, enhancing the durability and accuracy of the device.
Implementation Method 1
piezoresistive silicon-on-insulator sensors
Implementation Method 2
The sensors dielectrically isolated from the substrate
Data Source
AI summary
A pressure transducer comprising a corrosion resistant metal diaphragm, having an active region, and capable of deflecting when a force is applied to the diaphragm; and a piezoresistive silicon-on-insulator sensor array disposed on a single substrate, the substrate secured to the diaphragm, the sensor array having a first outer sensor near an edge of the diaphragm at a first location and on the active region, a second outer sensor near an edge of the diaphragm at a second location and on the active region, and at least one center sensor substantially overlying a center of the diaphragm, the sensors connected in a bridge array to provide an output voltage proportional to the force applied to the diaphragm. The sensors are dielectrically isolated from the substrate.