Resonant Pressure Sensor Structure for High-Pressure Linearity
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Solution Overview
Problem
Conventional resonant pressure sensors experience a 'balloon effect' at high static pressures, leading to degraded linearity and measurement precision due to peripheral deformation of the diaphragm, making it difficult to achieve high accuracy in environments with elevated static pressures.
Innovation Solution
A resonant pressure sensor design featuring a substrate with a cantilever structure and strain-mitigating holes, where the first and second resonators, made of semiconductor materials with differing impurity concentrations, detect changes in resonance frequency to isolate and accurately measure static pressure, thereby maintaining high linearity and precision across varying pressure ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional diaphragm structure is used in resonant pressure sensors, then the sensor can detect pressure changes through resonance frequency shifts, but the peripheral portion deforms at high static pressures causing the balloon effect and degraded linearity
Solution Approach 1:
The substrate is divided into a fixed portion and a separated portion that extends from the fixed portion. The resonator is disposed in the substrate-separated portion, which is separated from the housing-fixed portion by a gap filled with pressure-receiving fluid. This segmentation prevents the resonator from being directly affected by peripheral diaphragm deformation while still allowing it to detect pressure changes through strain in the substrate portion.
Solution Approach 2:
The substrate portion has different structural characteristics in different regions: the fixed portion is rigidly attached to the housing, while the separated portion is flexible and extends into the pressure-receiving fluid. This local differentiation allows the fixed portion to provide stable mounting while the separated portion responds to pressure changes without suffering from peripheral deformation effects.
2Measurement precision
If the resonator is directly integrated on the diaphragm surface, then pressure detection is achieved through strain detection, but the balloon effect causes sensitivity degradation at high static pressures
Solution Approach 1:
The pressure-receiving fluid acts as an intermediary between the housing-fixed portion and the resonator in the substrate-separated portion. The fluid transmits pressure changes to the resonator through the substrate portion while isolating the resonator from direct contact with the deforming diaphragm periphery, thereby maintaining measurement linearity at high pressures.
Solution Approach 2:
Instead of placing the resonator directly on the two-dimensional diaphragm surface, the invention extends the substrate into a third dimension by creating a substrate-separated portion that extends from the fixed portion. The resonator is disposed in this extended region, allowing pressure detection through volumetric strain in the substrate rather than surface strain alone, which reduces the balloon effect.
3Measurement precision
If a simple substrate structure is used, then manufacturing is easier, but the substrate cannot effectively mitigate strain or maintain linearity at high pressures
Solution Approach 1:
The substrate is segmented into a fixed portion and a separated portion with distinct functions. The fixed portion provides stable mounting to the housing, while the separated portion extends into the pressure-receiving fluid to detect pressure changes. This segmentation achieves high linearity without requiring complex additional components.
Solution Approach 2:
The substrate portion serves multiple functions: it provides mechanical support for the resonator, transmits pressure changes from the fluid to the resonator, and mitigates strain through its extended geometry. This multi-functionality achieves high measurement precision without proportionally increasing device complexity.
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 design ensures high linearity and excellent measurement precision regardless of the static pressure magnitude, effectively mitigating the balloon effect and enhancing measurement accuracy in high-pressure applications.
Implementation Method 1
detects as a change value of a resonance frequency based on a strain arising in the substrate portion according to a static pressure applied by the pressure-receiving fluid
Implementation Method 2
a strain arising in the substrate portion according to a static pressure applied by the pressure-receiving fluid
Data Source
AI summary
A resonant pressure sensor with improved linearity includes: a substrate including a substrate-separated portion separated from a housing-fixed portion; a first resonator that: is disposed in the substrate-separated portion; and detects a change of a first resonance frequency based on a strain in the substrate caused by static pressure applied by a pressure-receiving fluid; a second resonator that: is disposed in the substrate; detects a change of a second resonance frequency based on the strain in the substrate; and has a pressure sensitivity of the second resonance frequency; and a processor that: measures the static pressure based on the detected change of the first resonance frequency; and corrects the static pressure according to internal temperature of the pressure sensor based on a difference between the second resonance frequency and the first resonance frequency.