Magnetoresistive Z-axis Gradient Sensor Chip with Flux Guide
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Solution Overview
Problem
Current magnetoresistive sensors, such as GMR and TMR, face challenges with complex manufacturing processes, limited magnetic field sensitivity, and uneven magnetic field distribution when measuring Z-axis magnetic fields, while Hall Effect sensors have low sensitivity and stability issues.
Innovation Solution
A magnetoresistive Z-axis gradient sensor chip using a standard manufacturing process for GMR and TMR sensors, combined with a Z-axis sensor back-bias magnet, detects the gradient of the Z-axis magnetic field with in-plane sensing axes, featuring flux guide devices made of soft magnetic alloys to enhance sensitivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall Effect sensor is used to measure Z-axis magnetic field, then Z-axis sensing capability is achieved, but magnetic field sensitivity is low and stability is poor
Solution Approach 1:
The patent introduces a flux guide device as an intermediary component between the magnetic field source and the magnetoresistive sensor. This flux guide converts the Z-axis magnetic field into an in-plane magnetic field component that the magnetoresistive sensor can detect, thereby achieving high sensitivity Z-axis magnetic field measurement using in-plane sensing technology
Solution Approach 2:
The patent changes the sensing direction parameter from Z-axis (perpendicular) to in-plane (parallel) by using flux guide devices to transform the magnetic field orientation. This allows magnetoresistive sensors to effectively measure Z-axis magnetic fields by detecting the converted in-plane field components
2Ease of manufacture
If GMR or TMR sensor with in-plane sensing axis is used, then manufacturing process is simplified, but Z-axis magnetic field measurement capability is limited
Solution Approach 1:
The flux guide device serves as a mediator that enables in-plane magnetoresistive sensors to measure Z-axis magnetic fields. It transforms the three-dimensional Z-axis field into in-plane field components that the sensor can detect, thus maintaining manufacturing simplicity while achieving Z-axis measurement capability
Solution Approach 2:
The patent uses flux guide devices to convert the magnetic field measurement from a direct Z-axis detection problem into an in-plane detection problem. By introducing this dimensional transformation, the sensor can measure perpendicular magnetic fields using parallel sensing elements
3Shape
If back-bias magnet with deep groove is used for in-plane sensing, then magnetic field distribution becomes uneven, but structure becomes relatively complex
Solution Approach 1:
The flux guide device acts as an intermediary that simplifies the back-bias magnet structure. Instead of requiring complex deep grooves, the flux guide channels the magnetic field to create the necessary in-plane components, resulting in both simpler structure and more uniform field distribution
Solution Approach 2:
The flux guide device creates localized magnetic field concentration and direction control at specific regions. By strategically positioning and shaping the flux guide, it generates the required in-plane field components locally without requiring complex overall magnet structures
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 provides higher magnetic field sensitivity, improved stability, and a simpler structure compared to Hall Effect sensors, enabling effective measurement of Z-axis magnetic field gradients with lower power consumption and smaller size.
Implementation Method 1
the flux guide devices are used to convert the component of the Z-axis magnetic field generated by the magnetic medium into a sensing direction along the magnetoresistive sensing units
Implementation Method 2
magnetoresistive sensor units located on the Si substrate and electrically interconnected into a full bridge gradiometer or half bridge gradiometer
Data Source
AI summary
A magnetoresistive Z-axis gradient sensor chip, which is used to detect the gradient in the XY plane of a Z-axis magnetic field component generated by a magnetic medium; the sensor chip comprises a Si substrate, a collection of two or two groups of flux guide devices separated a distance Lg and an arrangement of electrically interconnected magnetoresistive sensor units. The magnetoresistive sensor units are located on the Si substrate and located above or below the edge of the flux guide devices as well; the flux guide devices convert the component of the Z-axis magnetic field into the direction parallel to the surface of the Si substrate along the sensing axis direction of the magnetoresistive sensing units. The magnetoresistive sensor units are electrically interconnected into a half bridge or a full bridge gradiometer arrangement, wherein the opposite bridge arms are separated by distance Lg. This sensor chip can be utilized with a PCB or in combination with a PCB plus back-bias magnet with casing. The sensor measures the Z-axis magnetic field gradient by using magnetoresistive sensors with in-plane sensing axes. This sensor chip has several advantages relative to a Hall Effect sensor device, including smaller size, lower power consumption, and higher magnetic field sensitivity.