Patent ID: 8578761

Claim:
A concentration sensor device comprising: a sensor unit to detect a concentration of a specific component contained in liquid; a substrate having a first face on which the sensor unit is arranged, the substrate having a second face which is opposite to the first face; a sedimentation limit unit integrally arranged with the sensor unit or arranged at an upstream side of the sensor unit in a flowing direction of the liquid; and an electrode portion arranged on the second face of the substrate, the electrode portion and the sensor unit sandwiching the substrate, wherein the sensor unit has a comb-teeth shaped electrode pattern made of a first piezoelectric element made of PZT, the electrode portion defines a potential difference between the electrode pattern and the electrode portion, the sedimentation limit unit is configured to prevent sedimentation of a foreign object on the sensor unit, the sedimentation limit unit includes a second piezoelectric made of PZT element to vibrate when electricity is supplied so as to promote the foreign object to be separated from the sensor unit, and the second piezoelectric element of the sedimentation limit unit is defined by the first piezoelectric element of the electrode pattern of the sensor unit, the comb-teeth shaped electrode pattern of the sensor unit further comprises a first comb-teeth electrode and a second comb-teeth electrode, the first and second comb-teeth electrodes have comb-teeth shapes disposed to face each other, the sensor unit detects the concentration of the specific component contained in a mixture fuel by detecting a permittivity or a relative permittivity between the first comb-teeth electrode and the second comb-teeth electrode that face each other.