Patent ID: 7618105

Claim:
A liquid sensor comprising: a vibration cavity forming base portion having a first surface and a second surface opposite to each other, in which a cavity for receiving liquid as a detection object is opened at a side of the first surface, and a bottom of the cavity is capable of vibrating; a piezoelectric element including a first electrode formed at a side of the second surface of the vibration cavity forming base portion, a piezoelectric layer laminated on the first electrode, and a second electrode laminated on the piezoelectric layer; and a flow path forming base portion laminated at the side of the first surface of the vibration cavity forming base portion, in which a liquid supply path for supplying the liquid as the detection object to the cavity, and a liquid discharge path for discharging the liquid as the detection object from the cavity are formed, wherein the vibration cavity forming base portion includes a cavity plate in which a through hole forming the cavity is formed, and a vibration plate laminated on the cavity plate, the flow path forming base portion includes a flow path plate in which a main portion of the liquid supply path and a main portion of the liquid discharge path are formed, and an exit/entrance plate in which an entrance of the liquid supply path and an exit of the liquid discharge path are formed and which is laminated on the flow path plate, and the vibration plate, the cavity plate, the flow path plate, and the exit/entrance plate are formed of the same material and are integrally sintered.