Wide-field magnetometry using nitrogen-vacancy color centers with randomly oriented micro-diamonds
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-10-26 |
| Journal | Scientific Reports |
| Authors | Saravanan Sengottuvel, Mariusz MrĂłzek, MirosĆaw Sawczak, Maciej J. GĆowacki, Mateusz Ficek |
| Institutions | Institute of Fluid Flow-Machinery, GdaĆsk University of Technology |
| Citations | 23 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Wide-Field NV Magnetometry
Section titled âTechnical Documentation & Analysis: Wide-Field NV MagnetometryâReference: Sengottuvel, S. et al. Wide-field magnetometry using nitrogen-vacancy color centers with randomly oriented micro-diamonds. Scientific Reports 12, 17997 (2022).
Executive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates a low-cost, wide-field vector magnetometry platform utilizing Nitrogen-Vacancy (NV) centers in randomly oriented micro-diamond powder. This approach offers significant advantages over conventional bulk diamond or scanning probe methods, particularly for irregular surfaces and large-area mapping.
- Core Innovation: Wide-field Optically Detected Magnetic Resonance (ODMR) imaging using submicrometer-sized, randomly oriented fluorescent micro-diamonds deposited via Matrix-Assisted Pulsed Laser Evaporation (MAPLE).
- Application: Simultaneous mapping of spatially varying DC magnetic fields (vector components) over a large field of view (FOV, ~300 ”m).
- Material Advantage: Randomly oriented micro-diamonds allow for vector field reconstruction without complex alignment, paving the way for sensors applicable to irregular surfaces, fiber tips, and biological samples.
- Performance Metrics: Achieved an estimated magnetic field sensitivity of 4.5 ”T/âHz in continuous-wave (cw) ODMR mode, with an optimized FWHM of 10 ± 0.3 MHz.
- Methodology: Developed an automated MATLAB algorithm for extracting ODMR spectra and estimating magnetic field strength from hundreds of individual diamond spots simultaneously.
- 6CCVD Value Proposition: 6CCVD specializes in the high-purity MPCVD diamond materials (SCD and PCD) required to manufacture the high-quality, NV-rich micro- and nano-diamond powders necessary to replicate and advance this technology.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| NV Center Ground State | Triplet S=1 | N/A | Spin sublevels ms = 0 and ms = ±1 |
| Zero-Field Splitting (D) | 2.87 | GHz | Room temperature resonance frequency |
| Magnetic Field Sensitivity | ~56 | MHz/mT | Proportional splitting at low magnetic fields |
| Bias Magnetic Field (Bbias) | 3.2 | mT | Applied via neodymium magnet to lift degeneracy |
| Excitation Wavelength | 530 | nm | Green LED pump beam (70 mW) |
| Fluorescence Detection Range | 600 - 800 | nm | NV center emission |
| Current Range (I) | -600 to +600 | mA | Applied to current-carrying wire |
| ODMR Contrast (Mean) | 4.5 | % | Variation observed between 1% and 8% |
| FWHM (Average, Power Broadened) | 16 | MHz | Caused by high microwave power |
| FWHM (Optimized) | 10 ± 0.3 | MHz | Measured at 600 mA current |
| Estimated Sensitivity (cw-ODMR) | 4.5 | ”T/âHz | Limited by low light intensity and NA |
| Field of View (FOV) | 307 x 245 | ”m2 | Imaged area containing ~410 diamond spots |
| Micro-Diamond Size | ~1 | ”m | Used in the MAPLE deposition |
Key Methodologies
Section titled âKey MethodologiesâThe experiment relied on a wide-field ODMR magnetic imaging setup combined with a specialized material deposition technique.
- Diamond Sample Preparation:
- Material: Fluorescent micro-diamond powder (MDNV1umHi, ~1 ”m size) was suspended in deionized water.
- Target Preparation: The suspension was cryogenically solidified (90-100 K) to serve as the target for laser ablation.
- Deposition: Matrix-Assisted Pulsed Laser Evaporation (MAPLE) was used to deposit a thin film of randomly oriented, sub-1-”m diamonds onto 1 x 1 cm2 glass coverslips under vacuum (10-5 mbar).
- Microwave (MW) Subsystem:
- A custom MW structure consisting of two straight copper striplines (100-”m wide, 350-”m separation) fabricated on a PCB board was used.
- MW frequency was swept around the 2.87 GHz resonance, amplified by a ZRL-3500+ power amplifier (+17 dB gain).
- DC current (-600 mA to +600 mA) was applied to the second stripline to generate the local magnetic field.
- Optical Detection Setup:
- Continuous-wave (cw) ODMR was performed using a 530 nm green LED pump beam (70 mW) focused via a 40X objective (NA 0.65).
- Fluorescence (600-800 nm) was collected by the same objective and recorded by an IDS UI-3240 CP camera (CMOS sensor, 12 bit depth).
- Data Acquisition and Analysis:
- Volumetric image data (2D slices across N MW frequencies) was captured simultaneously across the entire FOV.
- An automated MATLAB algorithm was developed to identify fluorescent diamond spots, extract the ODMR spectrum for each spot by pixel averaging, and fit the spectrum to a sum of eight Lorentzians (using the Levenberg-Marquardt algorithm).
- The resonance frequencies were used to reconstruct the total magnetic field vector B relative to the diamond lattice, leveraging the random orientation of the NV axes.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research validates the potential of diamond-based quantum sensing for wide-field applications, particularly where conventional bulk diamond is impractical. 6CCVD is uniquely positioned to supply the high-quality MPCVD diamond materials necessary to replicate, optimize, and scale this technology.
Applicable Materials for NV Magnetometry
Section titled âApplicable Materials for NV MagnetometryâThe quality and purity of the source diamond material directly determine the NV center concentration, coherence time, and resulting sensor sensitivity.
| Material Requirement | 6CCVD Solution | Technical Advantage |
|---|---|---|
| High-Purity Source Material | Optical Grade Single Crystal Diamond (SCD) | Provides the highest purity lattice for controlled nitrogen incorporation (during or post-growth) to create optimal NV- centers, crucial for achieving long coherence times (T2). |
| Large-Area/Cost-Effective Substrates | High-Quality Polycrystalline Diamond (PCD) | Available in plates/wafers up to 125mm diameter. Ideal for large-scale deposition of micro- or nano-diamond films via MAPLE or spin coating, offering superior thermal management compared to glass (addressing the thermal drift issue noted in the paper). |
| Advanced Sensing Layers | Thin Film SCD | SCD layers available down to 0.1 ”m thickness. Can be used to create highly uniform thin NV layers, offering an alternative to powder deposition for high-resolution scanning applications. |
| Vector Magnetometry Extension | Custom Nitrogen-Doped SCD | 6CCVD can engineer SCD with specific nitrogen concentrations to optimize the NV ensemble density required for high signal-to-noise ratio in wide-field ODMR. |
Customization Potential for Advanced Sensor Integration
Section titled âCustomization Potential for Advanced Sensor IntegrationâThe paper utilized a separate PCB for the MW striplines and a glass substrate, which contributed to thermal instability and positional drift. 6CCVD can integrate critical components directly onto the diamond sensor material.
- Integrated Metalization: 6CCVD offers in-house metalization services (Au, Pt, Pd, Ti, W, Cu). We can deposit the necessary Ti/Au or Ti/Pt striplines directly onto a polished SCD or PCD substrate, eliminating the need for external PCBs and improving thermal stability and MW coupling efficiency.
- Custom Dimensions and Polishing: We provide custom diamond plates up to 125mm (PCD) and substrates up to 10mm thick. Our superior polishing capabilities (Ra < 1nm for SCD, Ra < 5nm for PCD) ensure optimal optical coupling and minimal scattering, which is essential for maximizing the photon count rate (R) and improving the overall sensitivity (Ncw).
- Laser Cutting and Shaping: For specialized applications like fiber tips or micro-mechanical devices (as referenced in the paper), 6CCVD offers precision laser cutting services to create custom geometries from bulk diamond material.
Engineering Support
Section titled âEngineering SupportâThe transition from cw-ODMR (4.5 ”T/âHz sensitivity) to pulsed ODMR techniques is necessary to achieve the pT/âHz sensitivity levels reported in the literature. This requires precise material engineering.
6CCVDâs in-house PhD team specializes in MPCVD growth parameters and NV center physics. We offer consultation services to assist researchers in:
- Optimizing NV Density: Balancing NV concentration to maximize signal while minimizing spin-spin interactions that limit coherence time (T2).
- Material Selection: Choosing the optimal diamond grade (SCD vs. PCD) and thickness for specific applications (e.g., high-resolution scanning vs. large-area wide-field imaging).
- Surface Functionalization: Advising on surface preparation and metalization schemes for robust integration of MW and DC current structures.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract Magnetometry with nitrogen-vacancy (NV) color centers in diamond has gained significant interest among researchers in recent years. Absolute knowledge of the three-dimensional orientation of the magnetic field is necessary for many applications. Conventional magnetometry measurements are usually performed with NV ensembles in a bulk diamond with a thin NV layer or a scanning probe in the form of a diamond tip, which requires a smooth sample surface and proximity of the probing device, often limiting the sensing capabilities. Our approach is to use micro- and nano-diamonds for wide-field detection and mapping of the magnetic field. In this study, we show that NV color centers in randomly oriented submicrometer-sized diamond powder deposited in a thin layer on a planar surface can be used to detect the magnetic field. Our work can be extended to irregular surfaces, which shows a promising path for nanodiamond-based photonic sensors.