Vibronic multisensor

An apparatus for determining and/or monitoring at least one process variable of a medium, comprising:

• a sensor unit including a mechanically oscillatable unit, wherein at least one hollow space forms an internal volume in the mechanically oscillatable unit, and wherein the hollow space is filled with a potting compound,
• a first piezoelectric element, wherein the first piezoelectric element is arranged at least partially in the hollow space of the oscillatable unit such that the first piezoelectric element lies against a wall of the hollow space,
• wherein the apparatus is embodied
• to excite the mechanically oscillatable unit using an excitation signal such that mechanical oscillations are executed, to receive the mechanical oscillations of the oscillatable unit, and to convert the mechanical oscillations into a first received signal,
• to transmit a transmitted signal to the medium and to receive a second received signal, wherein the transmitted signal is an ultrasonic signal, and
• to determine and/or to monitor the at least one process variable based on the first and/or second received signal;
• wherein a coupling element is arranged in the internal volume of the mechanically oscillatable unit such that the coupling element is in mechanical contact with the first piezoelectric element, and the first piezoelectric element is arranged between the wall of the hollow space and the coupling element,
• wherein the coupling element includes securement means for securing the coupling element in the internal volume, wherein the securement means includes a spring element.