Mission impossible: droplet rolling up the bendable hill

This is a video showing a liquid droplet rolling up on a flexible microfluidic device, in which droplet flows along the slope formed by simply bending-deforming a 600 micron thick aluminium (Al) plate. The droplet was remotely pushed up by the acoustic wave propagating along the Al plate surface, which is generated by a thin layer of ZnO film (with electrode onto it).