Diamond NV Center Magnetic Field Sensor Using Mechanical Strain
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Solution Overview
Problem
Current magnetic field sensors, such as SQUIDs and diamond-based magnetometers, face challenges like the need for cryogenic cooling, sensor drift due to temperature changes, and increased complexity and power consumption, limiting their sensitivity and practicality for applications like magnetoencephalography.
Innovation Solution
A magnetic field sensor using a diamond crystal with nitrogen-vacancy centers that applies mechanical strain to shift resonance frequencies, allowing for the measurement of magnetic fields without requiring complex cooling or shielding, by varying deformation forces to detect fluorescence changes and determine field strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SQUIDs are used for magnetic field measurement, then measurement precision is improved, but device complexity and temperature control requirements worsen
Solution Approach 1:
The patent changes the operating temperature parameter from cryogenic (SQUID) to room temperature (diamond NV centers), eliminating the need for complex cooling systems while maintaining high measurement precision through optical detection of magnetic field-induced resonance shifts
Solution Approach 2:
The patent replaces the electromagnetic detection system of SQUIDs with an optical detection system using diamond nitrogen-vacancy centers, substituting complex electromagnetic shielding and cooling infrastructure with simple optical excitation and fluorescence detection
2Device complexity
If permanent magnets are used to generate bias magnetic field, then device complexity is reduced, but reliability worsens due to magnetization variation
Solution Approach 1:
The patent eliminates the need for external permanent magnets or current-carrying coils by using the diamond NV centers themselves as the magnetic field sensor, where the spin state of the NV center directly responds to ambient magnetic fields without requiring a separate bias field generation system
Solution Approach 2:
The patent extracts and removes the permanent magnet component from the system, relying solely on the intrinsic magnetic sensitivity of diamond NV centers to detect ambient magnetic fields, thereby eliminating sources of magnetization variation and sensor drift
3Reliability
If current-carrying coils are used to generate bias magnetic field, then reliability is improved, but device complexity and power consumption worsen
Solution Approach 1:
The patent removes the current-carrying coil system entirely, utilizing the natural magnetic field sensitivity of diamond NV centers to detect ambient fields without requiring active field generation, thereby eliminating power consumption and installation space requirements
Solution Approach 2:
The diamond NV center sensor performs both magnetic field detection and self-calibration through optical pumping, eliminating the need for external coil systems to generate and maintain bias fields
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 sensitive magnetic field measurement at room temperature with reduced complexity and power consumption, achieving high resolution without the need for cryogenic cooling or complex shielding, suitable for applications like magnetoencephalography.
Implementation Method 1
magnetic field sensor, in particular on the basis of strain-induced magnetic resonance shifts
Implementation Method 2
evaluating optically excited and read-out resonance frequencies which split in the magnetic field due to the Zeeman effect, wherein the frequency spacing of the split states is a function of the strength of the magnetic field
Implementation Method 3
Excitation light is then radiated into one or more measuring locations and the resulting fluorescence light from the respective measuring location is detected
Data Source
AI summary
A method for measuring a magnetic field includes radiating a microwave field having a first frequency into at least one measuring location in a crystal, which comprises optically excitable color center defects at the measuring location, radiating excitation light and detecting resulting fluorescence light, applying a deformation force which results in local mechanical strain, wherein an applied first deformation force is selected such that the first frequency corresponds to a resonance frequency of the color center defects under the action of the first deformation force without the magnetic field to be measured and the detected fluorescence light becomes minimal. The method further includes placing the sensor into the magnetic field to be measured to bring about a shift in the resonance frequency and varying the applied deformation force to compensate the shift in the resonance frequency until a minimum fluorescence signal is again acquired at a second deformation force.