Patent ID: 8733272

Claim:
An apparatus for ejecting fluid droplets, comprising: a substrate having a plurality of flow paths formed therein, each flow path including a respective pumping chamber and a respective nozzle, and the respective nozzle being configured to eject fluid droplets through a first surface of the substrate in response to actuation of the respective pumping chamber; an actuation assembly including a drive electrode layer over a second surface of the substrate opposite to the first surface, a piezoelectric layer over the drive electrode layer, and a reference electrode layer over the piezoelectric layer, the drive electrode layer being patterned to define an individually controllable drive electrode over each of two or more pumping chambers in the substrate, and the reference electrode layer including a continuous reference electrode spanning the two or more pumping chambers in the substrate, wherein the continuous reference electrode includes one or more apertures; and an integrated circuit layer attached to the actuation assembly on a side of the actuation assembly opposite to the substrate, and each of the one or more apertures encircling a respective electrical connection between the drive electrode in the actuation assembly and the integrated circuit layer.