Measuring Dielectrophoresis Force for Metallic and Non-metallic Particle Manipulations via a Quartz Tuning Fork Atomic Force Microscope

Dielectrophoresis (DEP) force is a widely studied topic because it has high utility in various research areas. Understanding DEP force is significant from the point of view of its efficient usage. Here, we confirmed the directions and magnitudes of DEP forces for metallic and non-metallic particle manipulations as well as force measurements via a quartz tuning fork atomic force microscopy (QTF-AFM) system. The 100 nm non-metallic silica particles having negative DEP force move toward the minimum point of the square of the electric field while the 60 nm metallic Au particles have positive DEP force. We also measured the magnitude of the DEP force in a liquid environment with electrodes. The experimentally measured DEP force magnitude was about 1 nN, which was similar to the simulation results, and the tendency of the measured force was consistent with that of the simulated case. This shows the possibility of using a QTF-AFM system as the fine force sensor in a liquid environment.