AFM tip-induced dielectrophoresis for 3D manipulation of nanoparticles

Atomic force microscopy (AFM) and dielectrophoresis (DEP) technologies have been used as excellent tools for nanomanipulation and nanoassembly. AFM-based manipulation exhibits excellent positioning and very high accuracy. The advantage of DEP is its ability to carry out parallel and massive manipulation of nanomaterials. In this study, we develop AFM tip-induced dielectrophoresis for three dimensional (3D) manipulation of nanoparticles by integrating AFM with DEP techniques. A spatially nonuniform electric field can be induced when applying alternating current (AC) voltage between the AFM tip and a glass substrate coated with a thin layer of indium tin oxide (ITO). This work mainly focuses on the theoretical analysis and numerical simulation of the electric-field distribution between the probe tip and the ITO glass. Finally, we experimentally demonstrate the manipulation and assembly of dielectric nanoparticles with an average diameter of 200 nm. Compared with the traditional DEP method, predesigned electrodes are not required. The spatial electric-field distribution depends on the position of the AFM probe. Therefore, AFM-tip-induced dielectrophoresis is more flexible and efficient.