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6CCVD Research

The Optimization of Microwave Field Characteristics for ODMR Measurement of Nitrogen-Vacancy Centers in Diamond

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2024-05-08
JournalPhotonics
AuthorsZhenxian Fan, Xing Li, Feixiang Wu, Xiaojuan Feng, Jintao Zhang
InstitutionsTsinghua University, China Jiliang University
Citations5
AnalysisFull AI Review Included

Technical Documentation & Analysis: ODMR Optimization for Cellular Thermometry

Section titled “Technical Documentation & Analysis: ODMR Optimization for Cellular Thermometry”

Executive Summary

Section titled “Executive Summary”

This research paper details the critical optimization of microwave antenna characteristics for high-sensitivity Optical Detection Magnetic Resonance (ODMR) thermometry using Nitrogen-Vacancy (NV-) centers in diamond, specifically targeting living cell environments.

  • Core Achievement: Successful simulation and experimental verification of optimized Double Open Loop Resonant (DOLR) microwave antennas, demonstrating superior performance for nanoscale temperature sensing in biological systems.
  • Application Focus: Precise temperature measurement in living cells (36 °C to 42.5 °C), requiring materials and systems that minimize thermal artifacts.
  • Key Performance Metric: The optimized DOLR antenna achieved a high Quality factor (Q) of 40.43 and excellent magnetic field uniformity (0.98 in a 1 mm x 1 mm region), significantly reducing the microwave heating effect compared to Broadband Large-Area (BLA) antennas (Q = 9.22).
  • Sensitivity Enhancement: Optimization resulted in the best ultimate sensitivity and Signal-to-Noise Ratio (SNR) for the DOLR antenna, with an optimal operating power range determined to be -15 dBm to -10 dBm.
  • Material Requirement: The study underscores the need for high-quality, low-strain diamond chips/sheets suitable for integration into complex microfluidic and antenna setups.
  • 6CCVD Value Proposition: 6CCVD specializes in providing the necessary high-purity Single Crystal Diamond (SCD) and custom fabrication services (thickness control, metalization, and dicing) required to replicate and advance this quantum sensing research.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Target Temperature Range36 to 42.5°CLiving cell activity research
Zero Field Splitting (D)2.87GHzNV- ground state at room temperature
D Variation (Cell Temp Range)~400kHzCorresponding to 36 °C to 42.5 °C
Optimized DOLR Center Frequency2.8744GHzOptimized for cellular environment
Optimized DOLR Bandwidth71MHzOptimized for cellular environment
Optimized DOLR Q Value40.43-Optimized for low heating effect
Optimized BLA Q Value9.22-Optimized for low heating effect
Optimal Microwave Power (DOLR)-15 to -10dBmBest SNR and minimal heating
Maximum Simulated Temperature Rise43.68KAt 6 dBm microwave power
Optimized DOLR Magnetic Field Strength344.9A/mPlanar magnetic field strength
Optimized DOLR Magnetic Field Uniformity0.98-In a 1 mm x 1 mm region
Optimized DOLR Return Loss (S11)-6.8dBmAt center frequency

Key Methodologies

Section titled “Key Methodologies”

The research employed a rigorous combination of electromagnetic simulation and experimental ODMR verification to optimize antenna performance for biological applications.

  1. Environmental Modeling: Established detailed simulation models incorporating the dielectric and electromagnetic properties of the cellular environment, including the culture medium, glass slide, and culture dish (e.g., dielectric constant $\epsilon$r = 5.42 for glass slide).
  2. Optimization Criteria Definition: Defined optimization goals based on NV- center resonance requirements: center frequency near 2.87 GHz, maximized Q value (to minimize heat loss), minimized return loss (S11), and maximized magnetic field uniformity.
  3. Univariate Parameter Control: Used a univariate control method to systematically simulate the effect of individual structural parameters (e.g., coupling gap gc, inner ring radius r1, ring width d) on center frequency and bandwidth for both DOLR and BLA antennas.
  4. Antenna Fabrication and Integration: Optimized antenna designs were fabricated and tested using “flaky diamond” samples integrated into the ODMR experimental setup.
  5. ODMR Spectral Measurement: ODMR spectra were measured across a range of microwave powers (-25 dBm to -5 dBm) using a 532 nm laser and an Acousto-Optic Modulator (AOM) for high-speed switching modulation.
  6. Performance Quantification: Antenna performance was quantified by comparing the Q value (center frequency/bandwidth) and the ratio of bandwidth/contrast (used as a proxy for Signal-to-Noise Ratio, SNR) to determine the optimal design and operating power.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

6CCVD provides the high-specification diamond materials and precision fabrication services necessary to meet the stringent requirements of nanoscale quantum sensing in complex environments, as demonstrated in this research.

Research Requirement6CCVD Solution & Value Proposition
High-Purity Diamond Substrates (for stable NV- centers)Optical Grade Single Crystal Diamond (SCD): 6CCVD offers high-purity SCD substrates, ideal for creating stable, low-strain NV- ensembles or single NV centers. Our SCD material ensures high optical transparency necessary for efficient 532 nm excitation and fluorescence collection (600 nm to 800 nm).
Thin Diamond Chips/Sheets (to minimize thermal mass)Custom Thickness Control (0.1”m - 500”m): The study highlights the critical issue of microwave heating. We provide SCD and Polycrystalline Diamond (PCD) wafers with precise thickness control, allowing researchers to minimize the thermal mass and mitigate the temperature rise observed (up to 43.68 K).
Precision Integration & Dicing (to match antenna geometry)Custom Dimensions and Fabrication: We offer plates/wafers up to 125mm (PCD) and provide precision laser cutting and dicing services. This ensures diamond chips can be fabricated to the exact millimeter-scale dimensions required for optimal placement within the DOLR or BLA antenna radiation elements.
Antenna Interfacing & Contacts (for low-loss microwave delivery)Advanced Metalization Services: 6CCVD offers in-house deposition of metals including Au, Pt, Pd, Ti, W, and Cu. This capability is essential for researchers needing to create robust, low-return-loss (low S11) electrical contacts or integrated microstrip lines directly onto the diamond surface for high-Q microwave delivery.
Surface Quality (for optical access and cell compatibility)Ultra-Smooth Polishing: We guarantee surface roughness Ra < 1nm for SCD and Ra < 5nm for inch-size PCD. This superior polishing minimizes light scattering and ensures the diamond surface is suitable for direct contact with living cells and culture media.
Replication and Extension of Quantum SensingExpert Engineering Support: 6CCVD’s in-house PhD team specializes in quantum material science and can assist researchers in selecting the optimal diamond material (SCD vs. PCD, specific doping levels) and integration strategies for complex ODMR, magnetic field, or pressure sensing projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

A typical solid-state quantum sensor can be developed based on negatively charged nitrogen-vacancy (NV−) centers in diamond. The electron spin state of NV− can be controlled and read at room temperature. Through optical detection magnetic resonance (ODMR) technology, temperature measurement can be achieved at the nanoscale. The key to ODMR technology is to apply microwave resonance to manipulate the electron spin state of the NV−. Therefore, the microwave field characteristics formed near the NV− have a crucial impact on the sensitivity of ODMR measurement. This article mainly focuses on the temperature situation in cellular applications and simulates the influence of structural parameters of double open loop resonant (DOLR) microwave antennas and broadband large-area (BLA) microwave antennas on the microwave field’s resonance frequency, quality factor Q, magnetic field strength, uniformity, etc. The parameters are optimized to have sufficient bandwidth, high signal-to-noise ratio, low power loss, and high magnetic field strength in the temperature range of 36 °C to 42.5 °C. Finally, the ODMR spectra are used for effect comparison, and the signal-to-noise ratio and Q values of the ODMR spectra are compared when using different antennas. We have provided an optimization method for the design of microwave antennas and it is concluded that the DOLR microwave antenna is more suitable for living cell temperature measurement in the future.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2001 - Biophysics and Physiology of Temperature Regulation in Thermogenic Flowers [Crossref]
  2. 2009 - Temperature-regulation of plant architecture [Crossref]
  3. 2018 - Germanium-vacancy color center in diamond as a temperature sensor [Crossref]
  4. 2012 - Mapping intracellular temperature using green fluorescent protein [Crossref]
  5. 2012 - Intracellular temperature mapping with a fluorescent polymeric thermometer and fluorescence lifetime imaging microscopy [Crossref]
  6. 2016 - Unveiling in vivo subcutaneous thermal dynamics by infrared luminescent nanothermometers [Crossref]
  7. 2021 - Ultra-sensitive hybrid diamond nanothermometer [Crossref]
  8. 2020 - A biocompatible technique for magnetic field sensing at (sub)cellular scale using nitrogen-vacancy centers [Crossref]
  9. 2005 - Bright fluorescent nanodiamonds: No photobleaching and low cytotoxicity [Crossref]
  10. 2007 - Characterization and application of single fluorescent nanodiamonds as cellular biomarkers [Crossref]

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