Patent ID: 7270386

Claim:
A liquid-detecting device comprising: a base having a first face and a second face opposite to each other, said base being provided with a concavity configured to receive a medium to be detected, said concavity being formed so as to be opened on a side of said first face, said concavity having a bottom configured to be capable of vibrating; a first electrode formed on a side of said second face of said base, said first electrode having a main portion formed in a size larger than said bottom of said concavity so as to cover an almost overall area corresponding to said bottom of said concavity, said main portion including a notch formed so as to extend inward over a position corresponding to a periphery of said bottom of said concavity; a piezoelectric layer having a main portion formed in a size smaller than said bottom of said concavity, a whole of said piezoelectric layer being arranged within said area corresponding to said bottom of said concavity, an almost overall said main portion of said piezoelectric layer excluding a part corresponding to said notch of said first electrode being laminated on said first electrode; an auxiliary electrode formed on a side of said second face of said base so as to extend from an outside of said area corresponding to said bottom of said concavity to an inside of said area corresponding to said bottom of said concavity, a part of said auxiliary electrode being positioned within said notch of said first electrode and supporting a part of said piezoelectric layer from said side of said second face; and a second electrode having a main portion laminated on said piezoelectric layer and an extension part extending from said main portion of said second electrode so as to be connected to said auxiliary electrode within said area corresponding to said bottom of said concavity.