Inertial Force Sensor Interlayer Insulating Layer Capacitive Coupling
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Solution Overview
Problem
Conventional inertial force sensors face challenges with high noise levels, large size, and reduced sensitivity due to capacitive coupling and stress-induced defects, which affect their reliability and accuracy in detecting angular velocities and accelerations.
Innovation Solution
The inertial force sensor employs an interlayer insulating layer with low relative permittivity to reduce capacitive coupling between driving and detection wiring, and uses a specific configuration of electrode layers and piezoelectric materials to enhance sensitivity and reliability, while also protecting against stress-induced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wirings are provided directly on arms without insulating layer, then device complexity is reduced, but capacitive coupling increases causing high noise levels
Solution Approach 1:
An insulating layer is introduced as an intermediary between the wiring and the arm structure. This insulating layer acts as a mediator that electrically isolates the wiring from the arm, thereby reducing capacitive coupling and the associated noise levels while maintaining the simplicity of the wiring structure.
2Measurement precision
If detection section area is increased to improve sensitivity, then measurement precision improves, but device area increases
Solution Approach 1:
The detection section is configured to extend in the thickness direction (Z-axis) of the arm in addition to the planar dimensions. This three-dimensional configuration allows the detection section to achieve a larger effective detection area and improved sensitivity without proportionally increasing the planar footprint of the device, thereby resolving the contradiction between detection sensitivity and device area.
3Measurement precision
If piezoelectric layer thickness is increased to improve detection capability, then measurement precision improves, but manufacturing precision requirements increase
Solution Approach 1:
A multi-layer composite structure is employed consisting of the piezoelectric layer sandwiched between upper and lower electrode layers. This composite configuration allows for optimized detection capability through the combined effects of the piezoelectric material and electrode structures, while the distributed thickness requirements across multiple layers reduce the stringency of manufacturing precision requirements compared to a single thick piezoelectric layer.
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 configuration results in a high-sensitivity, compact inertial force sensor with improved signal-to-noise ratio and reliability, capable of accurately detecting angular velocities and accelerations with reduced noise and increased durability.
Implementation Method 1
detection sections 111, 112, and 113 for detecting displacement of arms 105, 106, 107, and 108
Implementation Method 2
employs an interlayer insulating layer with low relative permittivity to reduce capacitive coupling between driving and detection wiring
Implementation Method 3
driving section 110 for driving arms 105, 106, 107, and 108
Data Source
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AI summary
An inertial force sensor includes a base, a connection electrode on the base; a flexible section supported by the base, a driving section on an upper surface of the flexible section, a detection section on the upper surface of the flexible section, an interlayer insulating layer on the upper surface of one of the driving section and the detection section, and a wiring electrically connecting another of the driving section and the detection section to a connection electrode via an upper surface of the interlayer insulating layer. This inertial force sensor can have improved sensitivity and a small size.