A portable modular NMR-DMF system for performing chemical/biological assays. The system comprises a PCB having an NMR electronic circuit thereon, wherein the NMR electronic circuit includes a figure-8 shaped RF coil generating a plane-parallel magnetic field. A planar DMF chip comprises a platform comprising an array of electrodes, the array of electrodes including a sensing site located under the figure-8 shaped RF coil. A portable magnet is disposed parallel to the DMF chip and the RF coil. The array of electrodes is configured to receive a sample under detection, move the sample along the array, mix the sample with a probe in the form of at least one droplet with target-specific nanoparticles, and move the mixed sample to the sensing site. A magnetic field corresponding to the mixed sample under detection is produced at the sensing site. The figure-8 shaped RF coil acts to transduce the magnetic field produced at the sensing site to a voltage signal. The NMR electronic circuit receives and processes the voltage signal to produce a resultant signal for analysis.