Pump pressure sensor

A back pressure sensor comprising at least one flexible beam having a pivot end and a drive connector end, a pivot means positioned at the pivot end thereof, the flexible beam having a first mounting position and a pump actuator mounting position between the pivot end and the drive connector end, a drive connector means on said drive connector end thereof for engaging a pump drive, a pump actuator means connected to said pump actuator mounting position for connecting with a positive displacement member of a positive displacement pump, at least one sensor beam having a distal end and a vibration damping end, a second mounting position between said distal end and vibration damping end thereof secured to the first mounting position of the flexible beam by a non-rotational connection, a first capacitor plate mounted on the flexible beam at a position adjacent to the pivot end thereof, and a second capacitor plate mounted adjacent the distal end of the sensor beam in a position facing the first capacitor plate at a distance which permits a capacitance coupling between the capacitor plates, a vibration damping means secured to the vibration damping end of the sensor beam for damping drive motion vibrations in the sensor beam.