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Advanced Sensor Research

Fiber‐Integrated Diamond Quantum Sensor for High‐Voltage Current Measurements

Qihui Liu, Shaoxiong Nie, Xiao Peng, Yaochen Zhu, Nan Wang, Yuqiang Hu, Xin Luo, Chun li, Maoheng Jing, Chunji Zhang, Wei Liu, Hao Chen, Jiangong Cheng, Zhenyu Wu

Published Oct 7, 2024• 16 citations

Abstract

Abstract In power network systems, there is an urgent demand for highly accurate and miniaturized sensors, owing to their high safety level and limited installation space. Current sensors in high‐voltage grids are required to accommodate harsh environments and provide accurate measurements of several kiloamperes. Thus, this study proposed an integrated quantum diamond sensor to facilitate high‐accuracy, large‐dynamic‐range current measurements. The design incorporated optical fiber and directional microwave (MW) antennas to drive the diamond sensor, which significantly reduced the size and power consumption on the high‐voltage side. Remote‐control and demodulation systems are installed more than 10 m away from the low‐voltage side. The proposed approach achieved zero power consumption on the high‐voltage side and ensured efficient signal transmission. A passive diamond probe manufactured using microfabrication processes facilitated miniaturization and practical deployment. Through parameter optimization, a magnetic detection sensitivity of 4.86 nT·Hz −1/2 is achieved at a safe distance of 11 m, which can be further optimized to 0.77 nT·Hz −1/2 with enhanced MW power. This sensor achieved a current measurement error of ±0.4% in the 1000 A measurement range. Thus, this study provides a new solution for the application of diamond quantum sensors in power systems.

DOI: 10.1002/adsr.202400106

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Abstract The negatively charged nitrogen vacancy (NV) color center in diamond is a type of point defect, which is extensively studied as a promising high‐sensitivity solid‐state magnetic field sensor. However, its transition from research to application is still limited due to the technical challenges of an integrated physical package. Here, an integrated diamond sensor is demonstrated with the essential component on the order of mm 3 , which is realized by a standard microfabrication process. A microfabrication‐compatible light guiding structure is constructed, providing photon detection efficiency of 66% and thus enabling a magnetic field detection sensitivity reaching 203 pT·Hz 1/2 . Incorporation of the sensor device with a magnetic yoke enables high‐precision wide‐range direct‐current sensing with current isolation. A current measuring range of 0–400 A with a minimum detection limit of 2 mA is achieved. By utilizing dual spin resonance modulation, the temperature drift is suppressed from 219 to 1.92 ppm∙°C −1 . This configuration provides new possibilities as a robust and scalable platform for current quantum sensing technologies.

Abstract Magnetic field sensors based on quantum sensing effects demonstrate significantly superior sensitivity compared to traditional sensors. Among these, diamond NV centers have emerged as the most promising quantum magnetic field sensors for practical industrial implementation at room temperature. However, current applications of diamond NV centers in power measurement face challenges due to insufficient measurement response speed. To address this challenge, this paper designs a rapid diamond NV-center magnetic field measurement system based on fast demodulation and ultrafast frequency agility. To this end, this paper employs a field-programmable gate array (FPGA) board-level device to implement signal demodulation and microwave control, thereby enabling a rapid magnetic field measurement system for diamond NV centers with fast demodulation and ultrafast frequency switching. By outputting current through a current source to a double-layer Helmholtz coil, the system generated a z-axis magnetic field. The system achieved a current measurement accuracy of 0.08% within the range of 0.5–10 A, with a static magnetic field sensitivity exceeding 8.30 nT/Hz 1 / 2 . The designed system achieves signal demodulation within less than 80 μs and frequency hopping of modulated microwave signals within less than 1 μs. Compared to benchtop systems, the measurement response speed has been improved from the second-level timescale to the millisecond-level timescale.

Negatively charged nitrogen-vacancy (NV) centers in diamond have been extensively studied as a promising high sensitivity solid-state magnetic field sensor at room temperature. However, their use for current sensing applications is limited due to the challenge of integration and miniaturization of the diamond NV sensor. Here, we demonstrate an integrated NV sensor fabricated with standard microfabrication process. The sensor device incorporated with a toroidal magnetic yoke enables a high-precision wide range direct current sensing with galvanic isolation. The performance of the diamond NV current sensor in an open loop configuration has been investigated. A current measuring range of 0 A ~ 1000 A with an uncertainty of 46 ppm are achieved. Taking advantage of dual spin resonance modulation, temperature drift is suppressed to 10 ppm/K. This configuration opens new possibilities as a robust and scalable platform for current quantum sensing technologies.

The nitrogen–vacancy center in diamond enables highly sensitive magnetic-field measurements. In this work, we demonstrate an excellent sensitivity of 7.9 pT·Hz –1/2 in the near-DC range of 1 to 1000 Hz. This performance is achieved using a 35 mW laser power and 1 mW microwave power enabled by 561 nm laser excitation and the resonant-antenna design. By leveraging dual resonance with intrinsic π shift for real-time common-mode rejection, this technique effectively suppresses low-frequency noise and pushes the 1/ f corner frequency down to 1 Hz, with a measured sensitivity at 1 Hz of 10.6 pT·Hz –1/2 . The magnetometer also exhibits excellent capability in detecting magnetic anomalies, promoting the practical use of diamond quantum sensors in biomedical, geophysical, and other real-world applications.