Patent ID: 6921160

Claim:
A piezo-electric device comprising: a base having a first surface and a second surface positioned opposite to each other, said base including a cavity for receiving a medium to be detected, said cavity having a bottom and being formed so as to be opened on a side of said first surface, said bottom of said cavity being formed so as to vibrate, a first electrode layer formed on a side of said second surface, said first electrode having a body formed in a region corresponding to said cavity, a piezo-electric layer laminated on said first electrode layer, said piezo-electric layer having a body formed in a region corresponding to said cavity and an extension part extending from said body beyond a position corresponding to a periphery of said cavity, an auxiliary electrode layer formed on a side of said second surface of said base, at least a part of said auxiliary electrode layer being positioned between said second surface and said extension part of said piezo-electric layer so as to support said extension part of said piezo-electric layer, and a second electrode layer laminated on said piezo-electric layer and connected to said auxiliary electrode layer, wherein, between said first electrode layer and said auxiliary electrode layer, an insulating gap for ensuring an insulating state between said first electrode layer and said auxiliary electrode layer is formed, said insulating gap being formed away from said position corresponding to said periphery of said cavity.