Inertial Sensor With Composite Magnetic Layers
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Solution Overview
Problem
Current inertial sensors using MEMS technology face challenges in increasing sensitivity for accurately detecting acceleration and inertia.
Innovation Solution
The design incorporates a base portion, weight portion, and connection portion with a first sensing element unit featuring a magnetic layer, reference magnetic layer, and nonmagnetic intermediate layer, which deforms with changes in relative position, utilizing the inverse magnetostriction effect to sense strain and resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional piezoresistance MEMS technology is used, then the device structure is simple and manufacturing is easier, but the sensitivity and gauge factor are insufficient
Solution Approach 1:
The patent employs a composite magnetic layer structure consisting of a first magnetic layer, a nonmagnetic intermediate layer, and a second magnetic layer. This composite structure enables the inverse magnetostriction effect, where strain applied to the magnetic layers causes changes in magnetization direction, which are detected as resistance changes. This composite material approach achieves high sensitivity (gauge factor of 100 or more) that cannot be obtained with conventional single-material piezoresistance sensors.
Solution Approach 2:
The patent utilizes the inverse magnetostriction effect, which is a parameter change phenomenon where mechanical strain (deformation) is converted into magnetic property changes (magnetization direction). The connection portion's deformation under acceleration causes strain in the magnetic layers, changing their magnetization directions relative to each other, which produces detectable resistance changes. This parameter transformation enables high-sensitivity detection.
2Measurement precision
If the magnetic layer structure is implemented, then sensitivity and gauge factor increase significantly, but the manufacturing process becomes more complex
Solution Approach 1:
The patent employs magnetic field application as a controllable parameter to set the initial magnetization directions of the first and second magnetic layers. By applying an external magnetic field during manufacturing, the magnetization directions can be precisely controlled to be substantially perpendicular to each other, which is critical for achieving high gauge factor. This parameter-based control method provides a feasible manufacturing approach despite the complex multi-layer structure.
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 enhances sensitivity, allowing for high-sensitivity detection of acceleration and inertia with improved gauge factors compared to traditional piezoresistance inertial sensors, achieving sensitivities previously difficult to attain with conventional technologies.
Implementation Method 1
a first sensing element unit provided on a first portion of the connection portion and including a first magnetic layer, a second magnetic layer, and a nonmagnetic first intermediate layer... utilizing the inverse magnetostriction effect to sense strain and resistance changes
Data Source
AI summary
An inertial sensor includes a base portion, a weight portion, a connection portion, and a first sensing element unit. The connection portion connects the weight portion and the base portion and is capable of being deformed in accordance with a change in relative position of the weight portion with respect to the position of the base portion. The first sensing element unit is provided on a first portion of the connection portion and includes a first magnetic layer, a second magnetic layer, and a nonmagnetic first intermediate layer. The nonmagnetic first intermediate layer is provided between the first magnetic layer and the second magnetic layer.