Position and Direction Tracking of a Magnetic Object Based on an Mx-Atomic Magnetometer

Abstract

Remote and non-invasive tracking of a moving magnetic object based on an atomic magnetometer has been developed recently. the sensitivity of atomic magnetometers is limited by mechanisms that relax the spin precession of alkali atoms. Meanwhile, some of these mechanisms such as magnetic field gradient are applicable in magnetic object tracking. Correspondingly, we have illustrated a way of operating an M x atomic magnetometer to measure the magnetic field and its gradient simultaneously for a moving magnetic microwire, which resulted in recording a spike-like signal. We described the dependency of the signal on the position, velocity, and direction of the microwire. According to the results, the measurement of the inhomogeneous local magnetic field gradient opens new ways for obtaining the direction of the velocity of magnetic objects accessible in cells with large sizes. Furthermore, the accuracy of the velocimetry was found as 40 µm/s which could be an important means for assessing the microvascular blood flow.

Detection of magnetic tracers with Mx atomic magnetometer for application to blood velocimetry

“…The resonance frequency is related to the stray magnetic field (B 0 ) of the solenoid on the cell location that was calculated as 4250 Hz. The sensitivity of the atomic magnetometer was obtained in the order of pT by measuring its noise spectral density 29 . Using the phase-locked loop, we measured any variation of light intensity associated with the deviation of the frequency δf and resonance curve slope which were proportional to the magnetic field and local magnetic field gradient of the moving magnetic target, respectively 29 .…”

“…Based on the results, the spike-like signal is produced by simultaneous changing the magnetic field and the local magnetic field gradient of the moving magnetic target. Magnetic target with stronger magnetization produces a stronger signal and the orientation of the velocity can inverse the amplitude of the signal 29 . However, the dependency of the signal to instantaneous velocity was ambiguous.…”

Magnetic‐Field‐Switchable Laser via Optical Pumping of Rubrene

“…Optical interrogation of magnetic fields could be used to study spintronic materials that lack inherently strong Kerr effects, [1] improve the resolution of magnetic resonance images (MRI), [2] and locate magnetic nanoparticles in biological assays. [3] Traditional approaches to magnetic field imaging that exploit weak magneto-optical interactions such as the Faraday effect are typically reliant on expensive effectiveness in avian magnetoreception, exploiting the magnetic field dependence of spin interactions in small organic molecules and nanoparticles may provide a compelling alternative to conventional magneto-optical materials for magnetic sensing.…”

Chip-Scale Ultra-Low Field Atomic Magnetometer Based on Coherent Population Trapping

“…Optically pumped atomic magnetometers are the most sensitive room-temperature magnetic sensors, which rely on precision measurements of atomic spin states under magnetic fields [ 1 ]. The sensitivity surpassing fT/Hz 1/2 level has been reported in a spin-exchange-free regime (SERF) [ 2 ], and the absence of cryogenic cooling makes it favorable for a wide range of applications, such as tracking of magnetic objects [ 3 , 4 ], space exploration [ 5 ], and medical signal detection [ 6 , 7 , 8 ]. In particular, miniaturization based on microfabricated vapor cells [ 9 , 10 , 11 ] paves the way towards mass-producible low-power versions of atomic magnetometers, namely chip-scale atomic magnetometers (CSAMs).…”