Open Diaphragm Gas Sensor for High-Pressure Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas sensors that operate based on resistive measuring principles face challenges when used at elevated pressures, as the measuring diaphragm can deform and rupture, limiting their reliability and applicability.
Innovation Solution
A sensor design that incorporates an open, coated measuring diaphragm situated between a sensor substrate and a cap substrate, with a reference diaphragm in an adjacent reference volume. This design includes analysis and reference heating elements, protected by a coating that prevents corrosion and deformation under high pressure and humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed measuring diaphragm is used in gas sensors, then the sensor structure is intact and sealed, but the diaphragm deforms and ruptures under elevated pressures greater than 500 mbar
Solution Approach 1:
The measuring diaphragm is designed with an open structure containing multiple clearances or openings that allow pressure equalization between the measuring volume and the external environment. This porous/open design prevents diaphragm deformation and rupture under elevated pressures up to 2 bar by eliminating the pressure differential that would otherwise cause mechanical failure, while still maintaining the diaphragm's sealing function for gas analysis.
Solution Approach 2:
The measuring diaphragm is segmented with multiple clearances distributed across its structure, creating multiple pressure equalization pathways. This segmentation allows the diaphragm to maintain its structural integrity under pressure by distributing the mechanical stress across multiple openings rather than relying on a single sealed barrier.
2Strength
If the measuring diaphragm is made open through clearances to prevent deformation, then pressure resistance is improved, but the diaphragm may be more susceptible to contamination and corrosion
Solution Approach 1:
A protective coating is applied as an intermediary layer on the surface of the measuring diaphragm and heating elements. This coating acts as a barrier that prevents direct contact between corrosive substances (such as moisture and analysis fluids) and the diaphragm material, thereby protecting against corrosion and contamination while allowing the diaphragm to maintain its open structure for pressure resistance.
Solution Approach 2:
The measuring diaphragm system combines the open-structured diaphragm material with a protective coating layer, creating a composite structure that simultaneously achieves pressure resistance through the open design and corrosion protection through the coating layer.
3Measurement precision
If heating elements are exposed on the diaphragm for thermal conductivity measurement, then measurement functionality is achieved, but the heating elements are vulnerable to corrosion and aging
Solution Approach 1:
The protective coating serves as an intermediary layer that covers the heating elements while allowing thermal energy to pass through to the analysis fluid. This coating protects the heating elements from direct exposure to corrosive moisture and analysis fluids, preventing corrosion and aging, while maintaining the thermal conductivity measurement functionality.
Solution Approach 2:
The protective coating is designed with properties that allow thermal energy transmission while blocking corrosive substances. The coating structure permits heat conduction from the heating elements to the analysis fluid for accurate measurement, while simultaneously providing a barrier against moisture and corrosive chemicals.
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 sensor achieves reliable operation under high humidity and pressure conditions, preventing diaphragm deformation and enabling measurements in environments with elevated pressures up to 2 bar, such as in fuel cell vehicles.
Implementation Method 1
at least one analysis heating element, situated on a measuring diaphragm, for heating the analysis fluid
Implementation Method 2
a reference heating element, situated on a reference diaphragm, for heating at least one reference gas
Implementation Method 3
a sensor for measuring a concentration of an analysis fluid based on a thermal conductivity principle
Data Source
AI summary
A sensor for measuring a concentration of an analysis fluid based on a thermal conductivity principle. The sensor includes at least one analysis heating element, situated on a measuring diaphragm, for heating the analysis fluid, and a reference heating element, situated on a reference diaphragm, for heating at least one reference gas. The measuring diaphragm and the reference diaphragm are adjacently situated between a sensor substrate and a cap substrate. The measuring diaphragm is situated in a measuring volume and the reference diaphragm is situated in a reference volume. The measuring diaphragm and the reference diaphragm each include at least one coating. The measuring diaphragm is opened by at least one clearance. A method for manufacturing a sensor is also described.