Nanowire Magnetic Sensor Device for Miniaturized Directional Detection

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Solution Overview

Problem

Existing magnetic field sensor devices, such as flux gates, face challenges in miniaturization and directional flexibility, particularly in constructing sensors perpendicular to the substrate plane, which limits their application in micromechanical components.

Innovation Solution

The use of nanowires, made from materials like Ni—Fe, where magnetization is reversed by an electrical current, eliminating the need for a coil and allowing for magnetic domain movement, enabling magnetic field detection through spin valves or pickup coils in thin-film technology on silicon substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If traditional flux gate sensors are constructed with excitation coils and magnetic cores, then magnetic field detection is achieved, but the device size is large and miniaturization is difficult

Engineering Contradiction:

Improvesensor device volumeVSAvoidcoil and core structure complexity

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the excitation coil from the traditional flux gate structure by using a nanowire whose magnetization can be directly reversed by electrical current. This removes the bulky coil component and enables miniaturization while maintaining the core functionality of magnetic field detection through periodic magnetization reversal.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical/electromagnetic coil system with an electrical current-based magnetization reversal mechanism in the nanowire. Instead of using an excitation coil to generate magnetic fields for saturation, the system uses direct electrical current to switch the nanowire's magnetization state, enabling compact integration with electronic circuits.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If flux gate sensors are constructed perpendicular to the substrate plane, then directional flexibility is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvedirectional detection flexibilityVSAvoidperpendicular structure fabrication

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent changes the operational parameter from requiring complex perpendicular coil-winding geometry to using electrical current pulses applied to a nanowire. The nanowire can be oriented perpendicular to the substrate plane, but the excitation is achieved through electrical current rather than magnetic fields from coils, simplifying the manufacturing process while maintaining vertical orientation benefits for z-direction field detection.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If nanowires are used with electrical current for magnetization reversal, then device miniaturization is enabled, but energy consumption increases

Engineering Contradiction:

Improvesensor device volumeVSAvoidenergy for magnetization reversal

Core Design Contradiction:

Volume of moving objectVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by concentrating the energy input precisely at the nanowire location where magnetization reversal is needed, rather than using distributed coil windings. The electrical current is applied locally to the nanowire, enabling efficient magnetization switching in a compact volume. This localized energy application reduces overall system energy consumption despite the high current density in the nanowire.

Inventive Principle:

Principle #3Local quality

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 approach enables the construction of miniaturized magnetic field sensors that can detect fields in any direction, improving signal-to-noise ratio and enabling flexible orientation, thus enhancing the sensitivity and versatility of magnetic field measurement systems.

Implementation Method 1

the usually required coil for reversing the magnetization of the magnetic core is dispensed with, since this takes place directly via the electrical current

Methodology Applied

Scientific EffectElectrical current induced magnetization reversal: Electromagnetic Induction

Implementation Method 2

the readout may be performed via a spin valve, a pickup coil or some other magnetic field detection device in the vicinity of the nanowire(s)

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS8866473B2Magnetic field sensor device, corresponding production method, and magnetic field measuring method

Publication Date: 2014.10.21 ROBERT BOSCH GMBH

AI summary

A magnetic field sensor device and a corresponding production method are described. The magnetic field sensor device includes a substrate, which has a trench, a ferromagnetic nanowire formed in the trench, a first electrical connection for the electrical connection of a first end of the ferromagnetic nanowire, a second electrical connection for the electrical connection of a second end of the ferromagnetic nanowire, and a magnetic field detection device for detecting a magnetic field in the region of the nanowire.