A Microfabricated Diamond Quantum Magnetometer with Picotesla Scale Sensitivity

This research reports a microfabricated diamond quantum magnetometer based on ensemble nitrogen-vacancy (NV) centers. The sensor device is fabricated with a standard MEMS process and integrated with optical fiber and photodiode (PD). The sensitivity of the sensor and signal-to-noise ratio (SNR) are determined by the detection efficiency of photons emitted from NVs in bulk diamonds. The miniaturized and portable diamond sensor shows a 132-fold enhancement of fluorescence collection efficiency over the fiber confocal system and an unshielded sensitivity of 334 pT•Hz
^-1/2
under ambient conditions. The essential sensor component is 1×1×0.1 cm
³
in volume. Sensors with improved integration and sensitivity are possible to be used for practical applications, such as magnetocardiography and precision current sensing.