MEMS Differential Pressure Sensor With Pivot Beam
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Solution Overview
Problem
Existing differential pressure measurement sensors face challenges such as leaks, complex manufacturing, and reduced precision due to separate membranes with different sensitivities, as well as contact with the external environment leading to reliability issues and short-circuits.
Innovation Solution
A differential pressure measurement sensor design featuring two membranes with a shared reference pressure and a rigid beam articulated by a pivot link, which isolates measurement means from the external environment, allowing direct differential pressure measurement while enhancing sensitivity through a lever-arm effect and capacitive detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealed membrane is used to avoid leaks between the two sides, then reliability is improved, but the measurement means may be in contact with the fluid causing short-circuits
Solution Approach 1:
The device is divided into two independent pressure chambers separated by a common membrane. Each chamber has its own pressure inlet, allowing the membrane to seal against pressure leaks while the measurement means remain outside the fluid environment, thus preventing short-circuits while maintaining reliability.
Solution Approach 2:
The common membrane acts as an intermediary element that transmits pressure differential information to the measurement means without requiring direct contact between the measurement means and the pressurizing fluids. This mediator allows reliable pressure measurement while isolating sensitive electronics from harmful fluid contact.
2Reliability
If two separate membranes are used to measure differential pressure, then the capacitor is protected from the exterior environment, but the membranes may have different sensitivities reducing precision
Solution Approach 1:
Two separate membranes are merged into a single common membrane structure that serves both pressure chambers simultaneously. This unified membrane ensures identical sensitivity and response characteristics for both pressure measurements, eliminating the precision errors that would arise from using two different membranes with varying sensitivities.
Solution Approach 2:
The common membrane provides homogeneous material properties and geometric characteristics across both pressure measurement points. This homogeneity ensures that both sides of the membrane respond identically to applied pressures, enabling precise differential pressure measurement while maintaining environmental protection.
3Adaptability or versatility
If pressure inlets are formed on both sides of the beam, then differential pressure measurement is enabled, but the assembly becomes complex
Solution Approach 1:
The common membrane serves multiple functions simultaneously: it acts as the pressure-sensitive element for both pressure chambers, provides the sealing barrier against leaks, and transmits the differential pressure signal to the measurement means. This multi-functionality eliminates the need for separate components for each function, thereby reducing assembly complexity while maintaining full differential pressure measurement capability.
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 robustness, high precision, and increased sensitivity by isolating measurement means from the external environment, reducing the risk of short-circuits and corrosion, and enabling precise differential pressure measurement with improved dynamic performance.
Implementation Method 1
piezoresistive detection for measuring the pressure difference... the variation in electrical resistance is proportional to the pressure difference
Implementation Method 2
The membrane forms with the intermediate substrate a variable capacitance capacitor, the measurement of said capacitance makes it possible to determine the differential pressure
Data Source
AI summary
MEMS and/or NEMS differential pressure measurement sensor comprising at least one first membrane and at least one second membrane, each suspended from a substrate, the first membrane having a face subjected to a reference pressure and a second face subjected to a first pressure to be detected, the second membrane having a first face subjected to the reference pressure and a second face subjected to a second pressure to be detected, a rigid beam of longitudinal axis articulated with respect to the substrate by a pivot link around an axis, said beam being solidly connected by a first zone to the first membrane and by a second zone to the second membrane such that the pivot link is situated between the first zone and the second zone of the beam, a sensor of measuring the movement of the beam around the axis, said sensor being arranged at least in part on the substrate.