Abstract: A method of poling a ferroelectric sample suitable for use in a fuel injector of an internal combustion engine, the method comprising providing a ferroelectric sample having a stack of ferroelectric layers, wherein adjacent layers are separated by internal electrodes, forming a first group and a second group of electrodes; applying a multiaxial pressure to the ferroelectric sample; reducing the bonding strength between each pair of adjacent ferroelectric layers and internal electrodes; and generating a first electric field between the first and second group of electrodes to pole each ferroelectric layer in a first poling direction.

Abstract: A filter element incorporates a filter medium formed in one example by two strips of paper which are rolled about a center tube so that the medium in section, has a zig-zag configuration. Apertures are provided to allow the passage of air from the pockets defined by the paper.