Janus particle microshuttle: 1D directional self-propulsion modulated by AC electrical field

A catalytic Janus particle is capable of gaining energy from the surrounding fuel solution to drive itself to move continuously, which has an important impact in different fields, especially the field of micro-systems. However, the randomness of self-propulsion at the microscale restricts its use in practice. Achieving a directed self-propelled movement would greatly promote the application of the Janus particle. We proved experimentally that an AC electric field was an effective way to suppress Brownian motion and control the direction of self-propelled movement. The self-propulsion and dielectrophoretic response of a 2 mu m Janus particle were observed and the related basic data were collected. Interdigital electrodes, 20 mu m in width, were energized in pulsed style to modulate the self-propulsion, which resulted in a shuttle-style motion in which a single Janus particle moved to and fro inside the strip electrode. The change of direction depends on its unique position: the catalyst side is always pointed outward and the orientation angle relative to the electrode is about 60 degrees. Numerical simulation also proved that this position is reasonable. The present study could be beneficial with regard to self-propulsion and AC electrokinetics of the Janus particle. (C) 2014 Author(s)