Scanning Localized Magnetic Fields in a Microfluidic Device with a Single Nitrogen Vacancy Center
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-02-05 |
| Journal | Nano Letters |
| Authors | Kangmook Lim, Chad Ropp, Benjamin Shapiro, Jacob M. Taylor, Edo Waks |
| Institutions | University of Maryland, College Park, National Institute of Standards and Technology |
| Citations | 13 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Integrated NV Magnetometry in Microfluidics
Section titled âTechnical Documentation & Analysis: Integrated NV Magnetometry in MicrofluidicsâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the integration of single Nitrogen Vacancy (NV) center magnetometry with a microfluidic platform, establishing a crucial technology for high-resolution chemical and biological sensing.
- Application Validation: The paper validates the use of single NV centers in diamond nanocrystals as highly sensitive, localized magnetic field probes within complex liquid environments (bio/chemical systems).
- Nanoscale Control: Achieved high-precision 3D manipulation of magnetic particles using combined electroosmotic flow control and magnetic actuation, attaining a positioning accuracy of 48 nm.
- High Sensitivity: Estimated shot-noise limited magnetic field sensitivity of 17.5 ”T Hz-1/2, comparing favorably with liquid-environment benchmarks.
- Integrated Sensing Platform: The methodology successfully integrates optical detection of Electron Spin Resonance (ESR) with on-chip lithographically patterned microwave (MW) antennas and microfluidic channels.
- 6CCVD Value Proposition: The studyâs results hinge on high-quality SCD material for reliable NV center properties and require advanced substrate fabrication (custom metalization and polishing) that 6CCVD provides at scale (up to 125mm).
Technical Specifications
Section titled âTechnical SpecificationsâThe following critical performance parameters and material specifications were achieved or utilized in the experimental setup:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Magnetic Field Sensitivity (Estimated) | 17.5 | ”T Hz-1/2 | Shot-noise limited sensitivity estimate |
| Spatial Resolution (Particle Positioning) | 48 (x) / 47 (y) | nm | Standard deviation of particle position control |
| Diamond Material Form Factor | Nanocrystal | 25 nm (mean diameter) | Single NV center host, deposited by spin coating |
| Substrate Thickness (Glass Coverslip) | 150 | ”m | Bottom surface of microfluidic device |
| NV Zero-Field Splitting Frequency | 2.87 | GHz | Reference frequency for ESR measurements |
| Excitation Laser Wavelength | 532 | nm | Continuous Wave (CW) |
| ESR Linewidth (ÎÎœ) | 7.2 | MHz | Hyperfine unresolved linewidth |
| Fluorescence Count Rate (R) | 45 | kCts/s | Count rate used in sensitivity calculation |
| MW Antenna Metal Stack | 10 nm Ti / 500 nm Au | Thickness | Lithographically patterned layer on glass |
| Magnetic Particle Material | Maghemite | Radius: 500 nm | Spherical magnetic bead |
Key Methodologies
Section titled âKey MethodologiesâThe experiment combined advanced nanofabrication, quantum sensing techniques (ODMR), and precise microfluidic control:
- Microfluidic Device Construction: Fabrication utilized polydimethylsiloxane (PDMS) molding bonded to a glass coverslip (150 ”m thick) to form intersecting channels, defining the control chamber.
- Quantum Sensor Deposition: Diamond nanocrystals (mean size 25 nm), pre-selected to contain a single NV center, were deposited onto the glass surface via a spin coating method.
- Microwave Antenna Integration: A bilayer metal stack (10 nm Titanium adhesion layer followed by 500 nm Gold) was lithographically patterned onto the glass coverslip to serve as an on-chip RF antenna for driving NV spin transitions.
- Optical Detection Setup: An inverted confocal microscope, excited by a 532 nm CW laser, was used for single NV fluorescence collection. Emission was spectrally filtered (600-750 nm) and spatially filtered via a pinhole aperture.
- 3D Particle Manipulation:
- Horizontal Control: Electroosmotic flow, induced by applied voltages at the channel ends, provided viscous drag to position the magnetic particle in the x-y plane with nanoscale feedback control.
- Vertical Control (Z-axis): A current-driven coil magnet below the device provided a vertical magnetic gradient force to pull the particle towards the glass surface, allowing Z-position control (up to 0.7 ”m distance used for sensing).
- Magnetometry: Optically Detected ESR (ODMR) was performed using a digital lock-in approach (1 KHz modulation) to measure Zeeman splitting, mapping the magnetic field distribution relative to the NV center position.
6CCVD Solutions & Capabilities: Enabling Scalable Quantum Microfluidics
Section titled â6CCVD Solutions & Capabilities: Enabling Scalable Quantum MicrofluidicsâThe demonstrated platform represents a significant convergence of quantum materials and bio-engineering. 6CCVD is an ideal partner to move this research from proof-of-concept into robust, high-throughput systems by providing high-purity MPCVD diamond materials and integrated fabrication services.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend this high-sensitivity magnetometry, researchers require diamond with extremely low nitrogen background and controlled surface quality.
| Application Requirement | Recommended 6CCVD Material | Key Features |
|---|---|---|
| High Sensitivity / Long Coherence Time | Electronic Grade SCD (Single Crystal Diamond) | Extremely low nitrogen background necessary for high-fidelity NV creation and maximizing T2 (spin coherence time), directly enhancing sensitivity (ηB). |
| Scalable Sensor Arrays / Vector Magnetometry | Optical Grade SCD Wafers | Available in custom dimensions and orientations (e.g., [100], [111]) to enable alignment of multiple NV centers or integration of large microfluidic arrays. |
| Integrated BDD Electrodes | Heavy Boron-Doped PCD (BDD) | For future integration where electrically conductive microfluidic channels or on-chip electrochemical sensing is required alongside NV centers. |
Customization Potential
Section titled âCustomization PotentialâThe experimental setup relied heavily on precise surface integration and custom on-chip components. 6CCVDâs in-house fabrication services streamline the transition from research prototypes to engineering-ready devices.
| Paper Component Requirement | 6CCVD Custom Capability | Engineering Advantage |
|---|---|---|
| High-Quality Nanodiamond Deposition Surface | SCD Polishing (Ra < 1 nm) | Ultra-low surface roughness ensures optimal deposition consistency and minimizes light scattering/background noise, crucial for fluorescence collection efficiency. |
| Integrated RF Antenna (10 nm Ti / 500 nm Au) | Custom Metalization Services | 6CCVD offers in-house patterning and deposition of Ti, Au, Pt, Pd, and other stacks directly onto diamond substrates (SCD or PCD), guaranteeing clean, reliable RF components. |
| Large-Scale Device Implementation | Large Format PCD Plates (Up to 125 mm) | Enables scaling the microfluidic platform for parallel testing and high-throughput sensing, addressing the scalability suggested in the paperâs conclusions. |
| Device Adaptation | Precision Laser Cutting and Dicing | Custom dimensions, trenching, and complex geometries can be executed on SCD or PCD wafers to precisely fit into specialized microfluidic or optical setups. |
Engineering Support
Section titled âEngineering SupportâThe successful development of next-generation NV-based systemsâincluding vector magnetometers, and electric field or temperature sensors mentioned in the paperâs conclusionârequires deep material expertise.
- 6CCVDâs in-house PhD-level engineering team provides consultation on optimizing material specifications, orientation, and nitrogen doping levels necessary to maximize spin properties (T1, T2) for integrated Quantum Sensing and Microfluidics projects.
- We specialize in tailoring thickness (SCD/PCD from 0.1 ”m up to 500 ”m) and size to meet the mechanical and optical requirements of advanced hybrid devices like the demonstrated magnetometry platform.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Nitrogen vacancy (NV) color centers in diamond enable local magnetic field sensing with high sensitivity by optical detection of electron spin resonance (ESR). The integration of this capability with microfluidic technology has a broad range of applications in chemical and biological sensing. We demonstrate a method to perform localized magnetometry in a microfluidic device with a 48 nm spatial precision. The device manipulates individual magnetic particles in three dimensions using a combination of flow control and magnetic actuation. We map out the local field distribution of the magnetic particle by manipulating it in the vicinity of a single NV center and optically detecting the induced Zeeman shift with a magnetic field sensitivity of 17.5 ÎŒT Hz(-1/2). Our results enable accurate nanoscale mapping of the magnetic field distribution of a broad range of target objects in a microfluidic device.