Ceramic Diaphragm Pressure Sensor with Localized Substrate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pressure sensors with metal diaphragms face issues such as plastic deformation from foreign matter, corrosion from acidic or alkaline fluids, and hydrogen embrittlement, which affect their resolution, strength, abrasion resistance, and corrosion resistance.
Innovation Solution
A pressure sensor with a ceramic pressure receiver featuring a diaphragm portion and a rim portion, along with a semiconductor substrate connected to the reverse surface of the diaphragm. The semiconductor substrate includes a base portion and a connected portion with a resonating strain gauge, designed to minimize thermal expansion coefficient differences and enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal diaphragm is used in the pressure sensor, then the diaphragm can be formed with good mechanical properties, but the diaphragm undergoes plastic deformation by collision with foreign matter, corrodes from corrosive fluids, or becomes brittle due to hydrogen embrittlement
Solution Approach 1:
The pressure receiver is formed of ceramic material (such as silicon nitride or silicon oxide) that combines high strength, corrosion resistance, and abrasion resistance. The ceramic diaphragm portion maintains mechanical integrity while resisting degradation from foreign matter, corrosive fluids, and hydrogen embrittlement, thus resolving the contradiction between strength and reliability.
2Strength
If a metal diaphragm is used in the pressure sensor, then the diaphragm can be formed with good mechanical properties, but the measured target may permeate through the diaphragm or the diaphragm may become brittle
Solution Approach 1:
Ceramic material is used for the pressure receiver diaphragm, which inherently resists hydrogen permeation and embrittlement. The ceramic structure provides a barrier that prevents hydrogen from penetrating through the diaphragm, eliminating the harmful effects associated with metal diaphragms while maintaining mechanical strength.
3Device complexity
If the connected portion of the semiconductor substrate has the same area as the base portion, then the structure is simple, but temperature-related errors increase due to thermal expansion coefficient differences
Solution Approach 1:
The connected portion of the semiconductor substrate is designed with a smaller area than the base portion, creating a localized structural feature that reduces the area subject to thermal expansion differences. This local modification minimizes temperature-related errors and improves measurement precision without significantly increasing overall 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 ceramic diaphragm and rim provide improved strength, abrasion resistance, and corrosion resistance, while the semiconductor substrate's design enhances resolution and reduces temperature-related errors, resulting in a pressure sensor with improved performance across various environments.
Implementation Method 1
at least one resonating strain gauge has been provided on the semiconductor substrate
Implementation Method 2
a piezoresistive strain gauge attached to the diaphragm
Implementation Method 3
designed to minimize thermal expansion coefficient differences
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A pressure sensor includes: a pressure receiver having a diaphragm portion that is deformed by receiving pressure on a pressure receiving surface thereof, and a rim portion formed around and integrally with the diaphragm portion and formed to be thicker than the diaphragm portion; and a semiconductor substrate that is connected to a reverse surface of the pressure receiving surface and detects strain in the diaphragm portion by means of a resonating strain gauge. The pressure receiver is formed of ceramic. The semiconductor substrate has: a base portion provided to face the reverse surface; and a connected portion that protrudes from the base portion toward the reverse surface and has a connected surface connected to the reverse surface. The connected portion has an area smaller than an area of the base portion in a case where the pressure sensor is viewed from a direction perpendicular to the reverse surface.