Segmented Resonant Pressure Sensor for High-Pressure Linearity
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Solution Overview
Problem
Conventional resonant pressure sensors experience degraded linearity and measurement precision when high static pressure is applied, leading to a 'balloon effect' that compromises their input and output characteristics.
Innovation Solution
A resonant pressure sensor design featuring a substrate with a cantilever structure and strain-mitigating holes, where the substrate is separated into fixed and separated portions, with first and second resonators made of single-crystal silicon having differing impurity concentrations, and a support substrate configuration that mitigates stress through isotropic pressure application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional diaphragm structure is used to detect pressure, then the sensor can detect pressure changes, but the linearity degrades and measurement precision decreases when high static pressure is applied due to the balloon effect
Solution Approach 1:
The substrate is divided into a fixed portion and a separated portion, with the resonator placed only in the separated portion. This segmentation prevents the entire substrate from deforming uniformly under high pressure, thereby eliminating the balloon effect and maintaining measurement linearity across a wide pressure range.
Solution Approach 2:
The resonator is positioned specifically in the substrate-separated portion where strain is concentrated, rather than distributing it across the entire diaphragm. This local placement ensures that the resonator experiences measurable strain even when the overall diaphragm deformation is minimized, maintaining sensitivity while improving linearity.
2Measurement precision
If the resonator is placed on the diaphragm surface to detect strain, then pressure can be detected through resonance frequency change, but the balloon effect causes peripheral deformation that reduces sensitivity at high static pressure
Solution Approach 1:
The substrate is segmented into fixed and separated portions, creating a structured design that concentrates strain in specific regions. This segmentation, while adding structural elements, provides a systematic solution to the balloon effect and improves overall measurement reliability.
3Device complexity
If a simple diaphragm-resonator configuration is used, then the device structure remains simple, but the balloon effect significantly degrades linearity when high static pressure is applied
Solution Approach 1:
The substrate is divided into fixed and separated portions, creating a structured design that concentrates strain in specific regions. This segmentation, while adding structural elements, provides a systematic solution to the balloon effect and improves overall measurement reliability.
Solution Approach 2:
The design transitions from a two-dimensional diaphragm surface to a three-dimensional structure with fixed and separated portions. This dimensional change allows the resonator to be positioned in a specific region where strain is optimized, improving linearity while maintaining reasonable structural 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
This design achieves high linearity and excellent measurement precision across a wide range of static pressures by minimizing the balloon effect and maintaining accurate pressure detection.
Implementation Method 1
detecting a change in a resonance frequency of a resonator, disposed on a surface of the sensor, caused by a strain arising in the resonator
Implementation Method 2
a strain arising in the resonator according to a static pressure applied by the pressure-receiving fluid
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
A resonant pressure sensor (1A; 1B) includes: a housing (50); a housing-fixed portion (2) fixed to the housing; a substrate (3; 3A; 3B; 3C) including a substrate-fixed portion (31) fixed to the housing-fixed portion (2) and a substrate-separated portion (32; 32A; 32B; 32C)) separated from the housing-fixed portion (2) and extending from the substrate-fixed portion (31); a first resonator (4) disposed in the substrate-separated portion (32; 32A; 32B; 32C) and configured to detect a change of a resonance frequency based on a strain in the substrate (3; 3A; 3B; 3C) caused by static pressure applied by a pressure-receiving fluid (F; K); and a processor (1). The pressure-receiving fluid (F: K) is intended to be interposed in a gap defined between the housing-fixed portion (2) and the substrate (3; 3A; 3B; 3C) and envelop the substrate (3; 3A; 3B; 3C). The processor (1) is configured to measure the static pressure based on the detected change of the resonance frequency.