A device and a method for determining and/or monitoring at least one process variable of a medium include a sensor unit having a mechanically oscillatable unit, at least a first piezoelectric element, a pressure detection unit for determining and/or monitoring a pressure, and an electronics unit. The device is embodied to excite the mechanically oscillatable unit using an excitation signal such that mechanical oscillations are executed, to receive mechanical oscillations of the oscillatable unit, to convert them into a first received signal, to transmit a transmitted signal and to receive a second received signal. The electronics unit is embodied, based on the first and/or second received signal, to determine the at least one process variable of the medium.