Fig. 2.

Multilayer composite with three layers showing (a) the arrangement of the active piezoceramic and passive polymer materials, and the internal and external electrodes; (b) poling orientation of the three layers. Note that the signal is usually the bottom and ground the top electrode and that this is representative of a single element of an array that can have from 64 to 256 individual elements, each with an independent signal electrode and typically a common ground electrode.