Structured Vacuum Measuring Cell Membrane for Contamination Resistance
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Solution Overview
Problem
Vacuum measuring cells, particularly membrane-based cells, are prone to contamination from process gases and residual gases, leading to inaccurate measurements, drift behavior, and reduced precision and reproducibility due to the formation of deposit layers on the membrane, which cannot be effectively prevented by existing shielding methods.
Innovation Solution
The membrane surface is structured with features such as step-like patterns, grids, or overhanging structures to divide and interrupt the deposit layer, reducing stress and contamination, combined with a helical diaphragm arrangement to further shield the membrane from contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a flat diaphragm (baffle) is used to shield the membrane, then the service life of the measuring cell is improved, but particles can still reach the membrane through scattering processes and cause contamination
Solution Approach 1:
The patent divides the membrane surface into multiple segments by creating structured patterns (such as radial segments or grid patterns) instead of using a flat continuous membrane. This segmentation prevents continuous deposit layers from forming across the entire membrane surface, thereby reducing the tensile and compressive stresses that would otherwise accumulate and cause measurement drift over time.
Solution Approach 2:
The patent transitions from a two-dimensional flat membrane surface to a three-dimensional structured surface with raised patterns or ridges. This dimensional change creates physical barriers that interrupt the path of contaminant particles and prevent uniform deposit layer formation, thereby reducing contamination effects while maintaining membrane functionality.
2Measurement precision
If the membrane is made very thin to achieve high sensitivity, then measurement precision is improved, but the membrane becomes more susceptible to contamination and stress from deposit layers
Solution Approach 1:
By segmenting the thin membrane surface into multiple smaller areas through structured patterns, the patent reduces the cumulative stress from deposit layers on any single continuous area. This allows the membrane to remain thin for high sensitivity while the segmented structure prevents stress accumulation that would otherwise compromise reliability.
Solution Approach 2:
The patent applies different structural properties to different regions of the membrane surface. The structured patterns create areas with varying mechanical properties, where the raised regions provide structural support and stress distribution while the valleys allow for controlled deformation. This local differentiation enhances both sensitivity and contamination resistance.
3Ease of manufacture
If a flat membrane surface is used, then manufacturing is simplified, but deposit layers form continuously across the surface causing measurement drift
Solution Approach 1:
The patent implements surface segmentation through structured patterns that can be integrated into existing membrane manufacturing processes. These patterns are created using standard fabrication techniques such as photolithography or laser structuring, allowing the membrane to maintain manufacturing simplicity while gaining the drift-reduction benefits of interrupted deposit layer formation.
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 significantly extends the service life of the measuring cell while maintaining high accuracy and reproducibility by minimizing the impact of contaminants on the membrane, reducing measurement errors and drift behavior.
Implementation Method 1
a thin membrane is deflected depending on the existing pressure that is to be measured
Implementation Method 2
the deflection of this membrane is measured and serves as a measure for the vacuum pressure to be measured
Implementation Method 3
the membrane surface has structures that reduce or prevent tension in the membrane, even if the measuring cell is exposed to a medium that is highly contaminating
Implementation Method 4
combined with a helical diaphragm arrangement to further shield the membrane from contaminants
Implementation Method 5
With capacitive membrane measuring cells, the deflection of the membrane is measured via the change in capacitance between the membrane and the solid
Implementation Method 6
In the case of optical membrane measuring cells, this deflection is recorded using optical methods, for example using interferometric methods
Data Source
Figure 1~2
Figure 3a~3e
AI summary
The invention relates to a vacuum measuring cell having a membrane (2, 41) which is arranged between two flat housing parts (1, 4), wherein the first housing part (1) forms a reference vacuum space (10) and the second housing part (4) forms a measuring vacuum space (9) having connection means (5) for connection to the medium to be measured, and means are provided for the purpose of measuring the displacement of the membrane, wherein the membrane surface (41a) which is exposed to the medium to be measured is in the form of a patterned surface in such a manner that stress bending caused by material from the measurement medium, which is deposited on the membrane, is considerably reduced.