Mechanical manipulation of magnetic nanoparticles by magnetic force microscopy

A method has been developed in this work for the mechanical manipulation of magnetic nanoparticles (MNPs). A helical curve was designed as the capture path to pick up and remove the target nanoparticle on a mica surface by a magnetic probe based on the magnetic force microscope (MFM). There were magnetic, tangential and pushing forces acting on the target particle during the approaching process when the tip followed the helical curve as the capture path. The magnetic force was significant when the tip was closer to the particle. The target particle can be attached on the surface of the magnetic probe tip and then be picked up after the tip retracted from the mica surface. Theoretical analysis and experimental results were presented for the pick-up and removal of MNPs. With this method, the precision and flexibility of manipulation of MNPs were improved significantly compared to the pushing or sliding of the target object away from the corresponding original location following a planned path.