Chip-Scale Optomechanical Magnetometer Using Cavity Resonance

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Solution Overview

Problem

Current technologies lack a compact and portable high-performance magnetometer capable of measuring magnetic fields effectively, limiting their application in various environments and devices.

Innovation Solution

A chip-scale magnetometer utilizing cavity optomechanics with an optomechanical oscillator, comprising a fixed substrate, a moveable mass, a photonic crystal, and a current source, which measures magnetic fields through the Lorentz force-induced displacement of the moveable mass, detectable by changes in the optomechanical cavity's resonance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If traditional magnetometer designs are used, then measurement performance is maintained, but device size and portability are compromised

Engineering Contradiction:

Improvemagnetometer sizeVSAvoidmagnetic field measurement performance

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent replaces traditional mechanical magnetometer components with an optomechanical system that uses optical fields to detect magnetic field-induced mechanical displacements. The Lorentz force deflects a mechanical element, and this deflection is measured optically through resonance frequency shifts, enabling miniaturization while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention transitions from direct mechanical measurement to optical field-based measurement by detecting resonance frequency changes. This dimensional shift from mechanical displacement measurement to optical resonance detection enables the system to achieve high precision in a compact form factor.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If magnetometer size is reduced for portability, then device compactness is improved, but measurement sensitivity deteriorates

Engineering Contradiction:

Improvemagnetometer sizeVSAvoidmagnetic field measurement sensitivity

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent substitutes mechanical measurement mechanisms with an optomechanical detection system. The mechanical element's deflection due to Lorentz force is transduced into optical signals through resonance frequency changes, allowing sensitive detection in a miniaturized device.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the measurement parameter from direct mechanical displacement to resonance frequency shift. This parameter transformation amplifies the detectable signal from small mechanical deflections, maintaining measurement sensitivity despite device miniaturization.

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If chip-scale integration is implemented, then device portability is improved, but structural complexity increases

Engineering Contradiction:

Improvemagnetometer sizeVSAvoidoptomechanical structure complexity

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single integrated optomechanical structure. The mechanical element serves both as the Lorentz force sensor and as part of the optical resonator, eliminating the need for separate mechanical and optical components and reducing overall structural complexity despite chip-scale integration.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The mechanical element in the optomechanical oscillator performs multiple functions: it acts as the force-sensing element subject to Lorentz force, as part of the optical cavity structure, and as the resonating element whose frequency is measured. This multi-functionality reduces the number of components needed in the chip-scale device.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables highly sensitive and portable magnetic field measurements, suitable for diverse applications, including geophysics research and micro/nanoelectromechanical systems, with improved sensitivity and compact design.

Implementation Method 1

The moveable mass may be moveable responsive to placement of the optomechanical oscillator in a magnetic field based on interaction of the magnetic field and the current

Methodology Applied

Scientific EffectLorentz force: Lorentz Force

Implementation Method 2

chip-scale high-performance magnetometers having cavity optomechanics

Methodology Applied

Scientific EffectCavity optomechanics: Resonance

Data Source

PatentUS9897666B2Chip-scale optomechanical magnetometer

Publication Date: 2018.02.20 JOHNS HOPKINS UNIVERSITY

AI summary

An optomechanical oscillator for measuring a magnetic field may include a fixed substrate, a moveable mass separated from the fixed substrate by a slot, a photonic crystal comprising an optomechanical cavity formed at the slot, and a current source operably coupled to provide current to the photonic crystal. The moveable mass may be moveable responsive to placement of the optomechanical oscillator in a magnetic field based on interaction of the magnetic field and the current. The magnetic field may be measureable based on displacement of the moveable mass.