Selection-focus coils de-signed for 3D FFL-based MPI may allow for spatial encoding without additional shift coils and provide relatively large FOV and field gradient with very flat FFL. Additionally, a single-sided FFL-based device which is capable of 3D imaging is disclosed. With sufficient current amplitudes, FFL could encode the whole volume of a small animal or penetrate deep into human organs such as the vascular system or lymph nodes. An MPI device based on the proposed selection scheme could be a compact and robust alternative to the state-of-the-art FFP (FFL)-based MPI scanners.