Target analyte detection devices include a housing having a potentiostat and a microcontroller coupled to the potentiostat. The device also includes a substrate having a plurality of electrodes on a first surface of the substrate. A first set of electrodes of the plurality of electrodes defines a first sample detection region. The substrate is removably attachable to the housing such that the first set of electrodes is coupled to the potentiostat upon attaching the substrate to the housing. The device also includes a magnet assembly couplable to a second surface of the substrate. The magnet assembly includes a magnet positioned in the magnet assembly such that a magnetic field from the magnet extends through the substrate and the first set of electrodes into an area above the first sample detection region upon coupling the magnet assembly to the substrate.
