Surface acoustic wave mediated dielectrophoretic alignment of rolled-up microtubes in microfluidic systems

The alignment behavior of solution dispersed rolled-up microtubes by surface acoustic waves (SAW) is demonstrated. In contrast to the random alignment of rolled-up insulated silicon oxide tubes, metallic chromium tubes can be effectively aligned and assembled into “tube-chains” parallel to the SAW propagation direction. The experiments suggest that the tube orientation is mainly determined by the dielectrophoresis (DEP) forces acting on the tubes. The DEP forces arise from the induced dipole moment of the tubes in the SAW generated piezoelectric field on the LiNbO₃ substrate.