With the help of microfluidics, so-called "labs-on-a-chip" can be realized - laboratories in miniature format. Special technical requirements have to be taken into account when working on the extremely small chip: Strong electrical forces occur and the viscosity of liquids increases. Adrian Lenkeit (15) and Jan Matthias Schäfers (16) from Bad Münstereifel developed control elements for use in the micrometer range that are based on piezoelectrically generated acoustic surface waves. In computer simulations, they demonstrated that the right wave patterns can be used to transport droplets and generate currents in the droplets. This makes it possible to mix chemicals or concentrate solid components in the center of the droplet.