A sensing device comprises a plurality of magnetoresistive (MR) sensors, at least one fluidic channel, and detection circuitry coupled to the MR sensors. Each MR sensor is configured to detect the presence of molecules (e.g., biologic molecules) labeled by magnetic nanoparticles (MNPs). The sensors are encapsulated by an insulating material that protects the sensors from the contents of the at least one fluidic channel. The insulating material has a surface within the fluidic channel that provides sites for binding the molecules to be detected. The detection circuitry is configured to detect (a) a characteristic of magnetic noise of each MR sensor, the characteristic being influenced by a presence or absence of one or more MNPs at each site, or (b) a change in resistance, current, and/or voltage drop of each MR sensor, wherein the change is influenced by the presence or absence of one or more MNPs at each site.