Patent ID: 8882213

Claim:
A fluid ejection system, comprising: a fluid ejection device including: a fluid supply chamber to store fluid; a plurality of ejection chambers including nozzles and corresponding ejection members to selectively eject the fluid through the respective nozzles; a channel to establish fluid communication between the fluid supply chamber and the ejection members; a temperature adjustment module to establish at least one temperature of the fluid of the fluid ejection device; a sensor unit having a sensor plate; and a generator unit to supply a multi-frequency excitation signal to the sensor unit, the sensor unit to transmit the multi-frequency excitation signal from the sensor plate through the fluid to a grounding member to obtain one of a range of voltage values and a range of current values on the sensor plate, and the sensor unit to detect at least one impedance in the fluid at the at least one temperature based on the one of the range of voltage values and the range of current values to obtain at least one detected impedance value; and a fluid identification module to identify a characteristic of the fluid based on the at least one detected impedance value to obtain an identified fluid characteristic.