Vibronic multisensor with pressure detection unit

A device for determining and/or monitoring at least one process variable of a medium, the device comprising:

• a sensor unit comprising:
• a mechanically oscillatable unit;
• a first piezoelectric element and a second piezoelectric element;
• a pressure detection unit adapted to determine and/or monitor a pressure of the medium,
• wherein the is first and second piezoelectric elements are configured to excite the mechanically oscillatable unit using an excitation signal such that mechanical oscillations are executed, to detect the mechanical oscillations of the oscillatable unit, to convert the mechanical oscillations into a first received signal,
• wherein the first piezoelectric element is configured to transmit an ultrasonic signal, and the second piezoelectric element is configured to receive the ultrasonic signal as a second received signal;
• and
• an electronics unit configured to:
• determine a first process variable based on the first received signal, a second process variable based on the second received signal, and the pressure of the medium based on a third received signal from the pressure detection unit;
• determine a pressure of a gas mixture in a container in which medium resides;
• determine the carbon dioxide content in the gas mixture and a resultant carbon dioxide concentration in the medium based on a change in the pressure of the gas mixture;
• and
• compensate for an effect of the carbon dioxide concentration in the medium on the determined the first process variable and/or the second process variable.