Measuring spins is the corner stone of a variety of analytical techniques including modern magnetic resonance imaging (MRI). The full potential of spin imaging and sensing across length scales is hindered by the achievable signal-to-noise in inductiv
e detection schemes. Here we show that a proximal Nitrogen-Vacancy (NV) ensemble serves as a precision sensing array. Monitoring its quantum relaxation enables sensing of freely diffusing and unperturbed magnetic ions in a microfluidic device. Multiplexed CCD acquisition and an optimized detection scheme enable direct spin noise imaging under ambient conditions with experimental sensitivities down to 1000 statistically polarized spins, of which only 35 ions contribute to a net magnetization, and 20 s acquisition time. We also demonstrate imaging of spin labeled cellular structures with spatial resolutions below 500 nm. Our study marks a major step towards sub-{mu}m imaging magnetometry and applications in microanalytics, material and life sciences.
We present a solid state magnetic field imaging technique using a two dimensional array of spins in diamond. The magnetic sensing spin array is made of nitrogen-vacancy (NV) centers created at shallow depths. Their optical response is used for measur
ing external magnetic fields in close proximity. Optically detected magnetic resonance (ODMR) is readout from a 60x60 $mu$m field of view in a multiplexed manner using a CCD camera. We experimentally demonstrate full two-dimensional vector imaging of the magnetic field produced by a pair of current carrying micro-wires. The presented widefield NV magnetometer offers in addition to its high magnetic sensitivity of 20 nT/$sqrt{Hz}$ and vector reconstruction, an unprecedented spatio-temporal resolution and functionality at room temperature.
