Magnetic manipulation is very promising for the motion control of micro- and nano-objects, which has wide applications in the mixing, trapping, colloidal assembly and object transport, and the recent progress in these areas is reviewed in this work.

The use of a magnetic field for manipulating the motion of magnetic particles in microchannels has attracted increasing attention in microfluidic applications. Generation of a flexible and controllable magnetic field plays a crucial role in making better use of the particle manipulation technology. Recent advances in the development of magnet systems and magnetic field control methods have shown that it has great potential for effective and accurate manipulation of particles in microfluidic systems. Starting with the analysis of magnetic forces acting on the particles, this review gives the configurations and evaluations of three main types of magnet system proposed in microfluidic applications. The interaction mechanisms of magnetic particles with magnetic fields are also discussed.

Two-dimensional (2D) ferromagnetism has attracted intense attention as it provides a platform for the investigation of fundamental physics and the emerged devices. Recently, the discovery of intrinsic 2D ferromagnet has enabled researchers to fabricate ultrathin devices, which can be controlled by external fields. Nevertheless, 2D ferromagnetic materials are mostly obtained by mechanical exfoliation methods with uncontrollable size and thickness, which make the device fabrication processes time-consuming and difficult to expand in industries. Therefore, the development of a controllable fabrication process for the synthesis of 2D intrinsic magnetic materials is necessary. In this study, a new 2D ferromagnet, chromium tellurium (CrTe), was successfully synthesized by the chemical vapor deposition (CVD) method, and the magnetism was studied by the magneto-optical Kerr effect (MOKE) technique. The results demonstrated that CrTe flakes exhibit hard magnetism with strong perpendicular anisotropy. As the thickness varies from 45 nm to 11 nm, the hard magnetism sustains quite well, with the Curie temperature T_C decreasing from 205 K to 140 K. Our study presents a new ultrathin hard magnetic material, which has the potential to be fabricated and applied in spintronic devices massively.