Tunneling Effect Element with Non-Magnetic Electrodes

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Solution Overview

Problem

Conventional tunneling-magnetoresistive-effect elements face challenges with stability due to external magnetic fields and lack versatility, especially in environments with large disturbance magnetic fields, and are affected by thermal expansion differences between electrode materials, leading to unstable output and limited applicability.

Innovation Solution

A tunneling effect element with non-magnetic conductive electrodes and an insulating layer forming a tunneling barrier, where both electrodes are made of the same material to minimize thermal expansion issues and resist external magnetic fields, and a resistance area product of 100 kΩ·µm² or less is maintained to ensure efficient signal transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If magnetic materials are used for electrodes in tunneling-magnetoresistive-effect elements, then the element can detect pressure changes through moment rotation, but the output becomes unstable when exposed to external magnetic fields

Engineering Contradiction:
Improvepressure detection precisionVSAvoidoutput stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent extracts and removes the magnetic property from the electrode materials, using non-magnetic materials instead. This eliminates the sensitivity to external magnetic fields while preserving the tunneling magnetoresistive effect for pressure detection through mechanical deformation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the material parameter of the electrodes from magnetic to non-magnetic, fundamentally altering the physical properties to eliminate magnetic field interference while maintaining the core tunneling effect functionality for accurate pressure sensing.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If different magnetic materials are used for lower and upper electrodes, then the tunneling-magnetoresistive-effect element can be constructed, but thermal expansion differences cause drift during temperature fluctuations

Engineering Contradiction:
Improveelement constructionVSAvoidresistance stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies homogeneity by using the same non-magnetic material for both lower and upper electrodes, eliminating thermal expansion differences between electrode materials and preventing resistance drift during temperature changes.

Inventive Principle:
Principle #33Homogeneity

3Reliability

If magnetic shielding surrounds the tunneling-magnetoresistive-effect element, then stable output is achieved in magnetic fields, but the element cannot be used with magnetic materials as the object to be detected

Engineering Contradiction:
Improveoutput stabilityVSAvoidapplicability to magnetic materials
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent removes the magnetic property from the electrodes, eliminating the need for magnetic shielding and thereby removing the limitation that prevented detection of magnetic materials as the object being measured.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If tunneling-magnetoresistive-effect elements are used, then simple circuit patterns are achieved, but the unique tunneling-transition probability characteristic is not utilized due to magnetic field interference

Engineering Contradiction:
Improvecircuit pattern simplicityVSAvoidtunneling effect utilization
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the electrode material parameter to non-magnetic, which enables the tunneling-transition probability characteristic to be properly utilized for precise measurement while maintaining the simplicity of the circuit pattern.

Inventive Principle:
Principle #35Parameter changes

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 a versatile and stable output that is not affected by external magnetic fields or thermal expansion differences, enabling reliable detection in various environments, including those with large disturbance magnetic fields and allowing for use with magnetic materials.

Implementation Method 1

an insulating layer forming a tunneling barrier, a lower conductive electrode of magnetic material formed on a bottom surface of the insulating layer and an upper conductive electrode of magnetic material formed on a top surface of the insulating layer

Methodology Applied
Scientific EffectTunneling effect:

Implementation Method 2

both electrodes are made of the same material to minimize thermal expansion issues and resist external magnetic fields

Methodology Applied
Scientific EffectMagnetic field resistance:

Implementation Method 3

both electrodes are made of the same material to minimize thermal expansion issues

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP1708291B1Tunneling effect element and physical quantity to electrical quantity transducer
Publication Date: 2011.09.28 TDK CORP
  • EP1708291B1 patent drawingFigure 1~3
  • EP1708291B1 patent drawingFigure 4~6
  • EP1708291B1 patent drawingFigure 7~8

AI summary

This invention provides a tunneling effect element that has versatility and that does not receive the effects of drift due to differences in the thermal-expansion coefficient of the lower and upper electrodes, and is not easily affected by external magnetic fields. The disclosed tunneling effect element 1 comprises: an insulating layer 11 that forms a tunneling barrier, a lower electrode 12 that is conductive and is formed on the bottom surface of the insulating layer 11, an upper electrode 13 that is conductive and is formed on the top surface of the insulating layer 11, and a transmission member 5 that is formed around the insulating layer 11, lower electrode 12 and upper electrode 13, and transmits the behavior of the object to be detected to the insulating layer 11.