MEMS Pressure Sensor Guard Segmentation for Stress Isolation
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Solution Overview
Problem
Pressure-sensing elements based on MEMS technology are susceptible to stress and foreign matter, which can affect the accuracy of pressure measurements due to the structural design and exposure of sensitive components.
Innovation Solution
A pressure-sensing element design featuring a membrane, substrate, guard, and base with trenches and slits that reduce stress transfer and prevent foreign matter exposure, including a pressure reference chamber and separate electrodes to enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sensitive portion is connected to the surrounding portion by an arm, then the structural integrity is improved, but stress from the surrounding portion can be transmitted to the sensitive portion, reducing measurement accuracy
Solution Approach 1:
The guard structure is divided into multiple segments with trenches and slits that create isolated regions. The sensitive portion is separated from the surrounding portion by these segmented structures, allowing structural support while blocking stress transmission paths.
Solution Approach 2:
The guard acts as an intermediary structure between the sensitive portion and the surrounding portion. It provides mechanical support while its segmented design with trenches and slits prevents stress from being transmitted to the sensitive portion, thus mediating between structural integrity and measurement accuracy requirements.
2Ease of operation
If the sensitive portion is exposed to the outside air through a ventilation hole, then the pressure sensing function is improved, but foreign matter can enter through the ventilation hole and contact the sensitive portion, reducing measurement accuracy
Solution Approach 1:
The guard structure serves as an intermediary barrier that allows pressure to be sensed while preventing foreign matter from reaching the sensitive portion. The trenches and slits create a protective maze that blocks contaminants while maintaining pressure transmission capability.
Solution Approach 2:
The membrane with diaphragm acts as a flexible shell that transmits pressure while the guard structure with trenches and slits provides protective enclosure, creating a system that senses pressure without exposing the sensitive portion to foreign matter.
3Stability of the object's composition
If the base is bonded close to the substrate, then the structural stability is improved, but stress from the substrate can be transmitted to the base, affecting measurement accuracy
Solution Approach 1:
The space between the base and substrate is segmented by trenches and slits in the guard structure. This segmentation creates isolated regions that prevent stress transmission while allowing the base to remain structurally stable through its bonded connections.
Solution Approach 2:
The guard structure with its segmented design acts as an intermediary layer between the base and substrate. It provides structural support while the trenches and slits block stress transmission paths, mediating between stability and precision requirements.
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 improves the accuracy of pressure measurements by minimizing the impact of stress and foreign matter, ensuring reliable operation and reducing product-to-product variation in internal pressure.
Implementation Method 1
a pressure reference chamber provided between the portion of the surface and the diaphragm to provide electrostatic capacitance
Data Source
AI summary
A pressure-sensing element includes a membrane, a substrate, a guard, and a base. The membrane includes a diaphragm. The substrate is opposite to the membrane in a thickness direction. The guard is between the membrane and the substrate and is bonded to the membrane and the substrate. The guard has a closed shape. The base is in an enclosed space defined by the membrane, the substrate, and the guard. The base is bonded to the membrane and is separated from the substrate and the guard. The base includes a first electrode opposed to the diaphragm with a pressure reference chamber between the first electrode and the diaphragm to provide electrostatic capacitance. The base except for the first electrode is bonded to the membrane. A trench extends in the thickness direction entirely through the membrane and partially through the guard.