Embodiments of the present disclosure provide for devices, methods for separating particles, and the like. In general, embodiments of the present disclosure include non-uniform magnetic field-assisted processes and devices for the separation of particles (e.g., cells) within a magnetic fluid. Under non-uniform magnetic fields, particles such as cells can experience the generated magnetic field direction to produce a magnetic buoyancy force, analogous to buoyancy force, as magnitude of the force is proportional to the volume of cell. This force can be used to spatially separate cells of different sizes. In some embodiments, devices for separating particles are provided having a magnetic device configured to direct a non-uniform magnetic force onto the magnetic fluid and the particles; and a plurality of outlets, wherein the non-uniform magnetic force causes the types of particles to be separated and flow into different outlets.