Magnetic resonance based detection. a. Principal of μNMR-based cell detection. When magnetic nanoparticles are bound to cells, they enhance the dephasing of surrounding water molecule’s NMR signal, causing the relaxation time (T2) to be reduced. b. A photograph of the DMR-III, a miniature magnetic resonance system for portable clinical use. The system consists of a permanent NdFeB magnet, micro-coil, and custom electronics. The system interfaces with a mobile device to facilitate system control and data sharing over wireless networks [56].