US Patent 7484416 Process control transmitter with vibration sensor

A transmitter for use in an industrial process control system, includes a process coupling configured to couple to a process fluid. A sensor housing has a cavity formed therein which is in fluidic communication with the process fluid. A diaphragm in the cavity isolates a portion of the cavity from the process fluid and moves in response to pressure applied by the process fluid. A first electrode in the isolated portion of the cavity is configured to form a first capacitance with the diaphragm and a second electrode in the isolated portion of the cavity configured to form a second capacitance with the diaphragm. Measurement circuitry coupled to the first and second capacitance measures a pressure of the process fluid based upon at least one of the first capacitance and second capacitance. The measurement circuitry further configured to measure vibrations in the process fluid based upon at least one of the first capacitance and second capacitance.