An apparatus having a device for moving a liquid comprises a piezoacoustic resonator element (11) having at least one piezoelectric layer (110) and two electrodes (111 and 112) present on the piezoelectric layer (110). The piezoacoustic resonator element (11) is designed such that, owing to a voltage being applied to the piezoelectric layer (110) by means of the electrodes (111 or 112), a volume oscillation of the piezoelectric layer (110) is excited at a resonant frequency. The piezoelectric resonator element (11) can be acoustically coupled in a suitable manner to a liquid for the purpose of transmitting the excited oscillation into the liquid for the purpose of moving the liquid. The apparatus may be in the form of a micromixer or in the form of a micropump and may comprise, in addition, sensor elements (41) for detecting the attachment of substance.