Highly sensitive handheld diamond magnetic field sensor allows for bio-diagnostics

Solid-state sensors using diamonds with nitrogen-vacancy centers have been shown to provide high sensitivity and spatial resolution for measuring magnetic fields, temperature, pressure and strain fields. These sensors use optical detections of fluorescence from the nitrogen-vacancy centers to detect electron spin resonance in a sample. However, their bulky size prevents their widespread use in practical applications.

Webb et al. presents a new handheld diamond nitrogen-vacancy magnetometer that can be used in practical applications outside of laboratories. The new magnetometer can be built with readily available, off-the-shelf and 3D printed components and is highly suitable for low frequency sensing applications.

The magnetometer uses a commercially available diamond that has been specifically cut and coated. The angled cut facets allow a high-power laser pump beam to travel through the full width of the diamond, and the coating on the back maximizes light collection.

Tests conducted on the handheld device show nanotesla sensitivity of magnetic fields. Achieving sub-nanotesla sensitivities with a modified device would likely be possible using a higher-powered laser pump.

The level of sensitivity and portability of the device make it useful for a wide range of potential applications, particularly for sensing magnetic fields in biological samples. Magnetoencephalography of the brain, which otherwise requires electrical probes, would be one such application. Other low frequency magnetic signals that could be measured by the device include diagnostics of mains power systems, like transformers and motors.

Source: “Nanotesla sensitivity magnetic field sensing using a compact diamond nitrogen-vacancy magnetometer,” by James L. Webb, Joshua D. Clement, Luca Troise, Sepehr Ahmadi, Gustav Juhl Johansen, Alexander Huck, and Ulrik L. Andersen, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5095241 .