Exchange-Biased Stress Sensor for Stable Magnetization Angle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional stress sensors face instability in operation due to the difficulty in maintaining the single domain state of the strain insensitive layer under applied strain, leading to unstable changes in the relative angle of magnetization direction, which affects the accuracy of stress detection.
Innovation Solution
A stress sensor with a laminated body comprising a first ferromagnetic layer, a first non-magnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer, where the antiferromagnetic layer includes Mn, fixes the magnetization direction of the second ferromagnetic layer using exchange bias, allowing the sensor to detect stress through changes in electric resistance based on the relative angle between the magnetization directions of the first and second ferromagnetic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an auxiliary magnetic field is applied to stabilize the single domain state of the strain insensitive layer, then the single domain state is stabilized, but the magnetization direction of the strain sensitive layer becomes less likely to change under the influence of the auxiliary magnetic field, resulting in reduced operation stability
Solution Approach 1:
The patent divides the magnetic sensor into two distinct layers: a strain insensitive layer with high coercivity that maintains stable magnetization direction, and a strain sensitive layer with low coercivity that responds to external stress. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between stability and sensitivity
Solution Approach 2:
The patent applies different magnetic properties to different parts of the sensor structure. The strain insensitive layer is designed with high coercivity to maintain stable magnetization, while the strain sensitive layer is designed with low coercivity to respond to stress changes. This local differentiation of magnetic properties enables both stability and operational responsiveness simultaneously
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 the operation stability of the stress sensor by stabilizing the relative angle between the magnetization directions during strain measurement, improving the detection sensitivity and accuracy of stress detection.
Implementation Method 1
The magnetization direction of the second ferromagnetic layer is fixed by an exchange bias caused by an exchange coupling with the antiferromagnetic layer
Implementation Method 2
The stress sensor detects a stress by the electric resistance depending upon the relative angle between magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer
Data Source
AI summary
Disclosed herein is a stress sensor that includes a stress detection layer including a laminated body including a first ferromagnetic layer, a first non-magnetic layer, a second ferromagnetic layer, and an antiferromagnetic layer stacked one on another. The antiferromagnetic layer includes Mn, and the magnetization direction of the second ferromagnetic layer is fixed by the exchange bias caused by the exchange coupling with the antiferromagnetic layer. The stress sensor detects a stress by an electric resistance depending upon a relative angle between magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer, the relative angle changing depending upon an externally applied stress.