Quantum diamond magnetometer approach paves way for imaging neurons with microscopic precision

Quantum diamond magnetometers have recently been shown to tune into weak biomagnetic fields from neurons and various muscle cells. Such techniques show promise for imaging networks of nerve cells with microscopic resolution.

Researchers developed an approach for optimizing quantum diamond magnetometers. Using a nitrogen-vacancy (NV) center in diamonds to resonate signals, Oh et al. have obtained magnetic measurements on the several tens of nanotesla scale with micrometer resolutions and temporal resolutions faster than one millisecond.

Such microscopy has been seen as an attractive modality through which to develop future drugs for neurological disorders such as Alzheimer’s disease and Parkinson’s disease.

“We believe our paper will encourage the field to improve the sensitivity of NV centers in diamonds,” said author Sangwon Oh. “Additionally, our continuously exciting NV diamond scheme, which doesn’t require a complicated optical system, would be commercially interesting to those needing small footprints and fast diagnosis.”

One major issue in work on quantum diamond microscopy is the drifting of NV spin levels due to temperature changes.

To overcome this, the group used a double resonance approach, exciting two different resonances with opposite spin quantum numbers. They also boosted the optically detected magnetic resonance using hyperfine driving, exciting multiple resonance frequencies simultaneously.

“These two features require simultaneously applying six different microwave frequencies for better sensitivity and stability in the magnetic field measurements,” Oh said. “We simplified our microwave system by mixing and combining multiple frequencies. Additionally, we systematically optimized vacancy and nitrogen concentrations for better performance.”

The group looks to improve the magnetic field sensitivity further by adopting diamond nanostructure and decoupling NV-spin interactions.

Source: “Quantum diamond microscopy with optimized magnetic field sensitivity and sub-ms temporal resolution,” by Sangwon Oh, Seong-Joo Lee, Jeong Hyun Shim, Nam Woong Song, and Truong Thi Hien, Journal of Applied Physics (2023). The article can be accessed at https://doi.org/10.1063/5.0142448 .