An apparatus, method and computer-readable medium configured to transport a constituent of fluid sample that binds to a functionalized magnetic particle. The apparatus includes a substrate connected to an input port, a magnetic nanowire, and either a temporally changing magnetic field generator or a spin-polarized current source. The magnetic nanowire is disposed in a surface of the substrate. The width and thickness of the magnetic nanowire are configured so that a domain wall propagating along the nanowire in response to the temporally changing magnetic field continuously couples to a superparamagnetic particle introduced into the input port.