Applications of atomic magnetometry in magnetic resonance imaging and magnetic molecular sensing

Atomic magnetometry was presented as a technique suitable in magnetic resonance imaging (MRI) and magnetic molecular sensing. The magnetometer was based on nonlinear magneto-optical rotation promoted by Cs atoms in a vapor cell with antirelaxation coating. A sensitivity of 150 fT/Hz^{1/2} for dc magnetic elds was achieved. Applications of atomic magnetometry in MRI were demonstrated using the remote detection scheme. Using a gadolinium chelate as the pH contrast agent, we demonstrated the response as 0.6 s-1mM-1 per pH unit at the ambient magnetic eld for the pH range 6-8.5. A stopped ow scheme was used to directly measure spin-lattice relaxation time T1 to determine the relaxivity values. The unknown pH value of a solution was measured using only 50 micro M of this contrast agent. For magnetic molecular sensing, three key parameters were considered, namely sensitivity, spatial resolution and molecular speci city. To enhance the sensitivity of the magnetometer, the sample region was separated from the detection region. This arrangement lessened noise due to air turbulence and altered the design of the magnetic shields that would allow a gradiometer con guration. With an improved sensitivity of 80 fT/Hz^{1/2}, we demonstrated that 7000 streptavidin-coated magnetic microparticles could produce 650 pT predicting single particle detection during one second measuring time. Spatial information was obtained using a scanning magnetic imaging scheme. The spatial resolution was 20 m with a detection distance of more than 1 cm. Using force-induced remnant magnetization spectroscopy, the molecular speci city was achieved. Magnetically labeled human CD4+ T cells were used as an example. Quantitative correlation was shown, which could be used in human immunode ciency virus diagnosis. Future works were discussed.