Capacitive Pressure Sensor Structure for Contamination and EMI Isolation
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Solution Overview
Problem
Existing pressure sensor devices face accuracy issues due to foreign matter adhesion and electromagnetic disturbances affecting electrostatic capacity, leading to reduced precision in pressure detection.
Innovation Solution
A pressure sensor device with a membrane layer, substrate layer, and intermediate layers that include electrode and guard portions, with movable portions sealed within internal spaces, preventing foreign matter adhesion and electromagnetic interference, and enhancing displacement stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the diaphragm is exposed to the outside environment, then the device structure is simple, but foreign matter adheres to the diaphragm and accuracy of pressure detection deteriorates
Solution Approach 1:
The patent applies a passivation film (thin film) to cover the diaphragm surface, creating a protective barrier that prevents foreign matter adhesion while maintaining the diaphragm's flexibility and pressure sensing functionality. This resolves the contradiction by adding minimal structural complexity to achieve improved measurement precision.
2Device complexity
If the diaphragm is exposed to the outside environment, then the device structure is simple, but electromagnetic waves from the outside disturb the diaphragm and accuracy of pressure detection deteriorates
Solution Approach 1:
The passivation film serves as an electromagnetic shielding barrier that blocks external electromagnetic waves from reaching and disturbing the diaphragm electrode, while allowing the diaphragm to remain exposed for pressure detection. This maintains structural simplicity while reducing harmful electromagnetic interference.
3Object-affected harmful factors
If a passivation film is provided on the membrane plate, then foreign matter adhesion is prevented, but stray capacitance is formed and accuracy of pressure detection deteriorates
Solution Approach 1:
The patent introduces an insulating layer as an intermediary between the passivation film and the diaphragm electrode. This insulating layer prevents stray capacitance formation by electrically isolating the passivation film from the electrode, while still allowing the passivation film to protect against foreign matter adhesion. This resolves the contradiction by adding a protective intermediary layer.
4Reliability
If the movable portion is sealed within internal space, then foreign matter adhesion is prevented and stability is improved, but device complexity increases
Solution Approach 1:
The patent implements a nested structure where the movable portion is positioned within an internal space defined by the diaphragm, substrate, and side wall portions. This nesting approach seals the movable portion to prevent foreign matter adhesion and improve stability, while the compact nested arrangement minimizes the increase in 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 solution inhibits reductions in pressure detection accuracy by isolating electrodes and movable portions from external contaminants and disturbances, stabilizing displacement, and increasing detection precision.
Implementation Method 1
a conductive movable portion supported by the diaphragm portion, apart from the substrate layer and the side wall portion, positioned in an internal space defined by the diaphragm portion, the substrate layer, and the side wall portion, the conductive movable portion facing and spaced from the electrode portion in the thickness direction
Data Source
AI summary
A pressure sensor device that includes: a membrane layer including a diaphragm portion; a substrate layer facing the membrane layer; a first intermediate layer between the membrane layer and the substrate layer; and a second intermediate layer between the first intermediate layer and the substrate layer. The first intermediate layer includes an electrode portion, and a guard portion joined to a part of the membrane layer different from the diaphragm portion and electrically insulated from the electrode portion. The second intermediate layer includes a side wall portion joined to the substrate layer and the guard portion, and a conductive movable portion supported by the diaphragm portion, apart from the substrate layer and the side wall portion, and in an internal space of the pressure sensor, the movable portion facing and spaced from the electrode portion, the movable portion configured to be moved when the diaphragm portion is displaced.