to a pressure gradient in a single direction only as described below with reference to fig8 referring now to fig4 piezoelectric stack 12 is shown in greater detail piezoelectric stack 12 comprises a series of monolithic piezoelectric elements 24 that are preferably plate like in structure and disposed within a sleeve 28 each piezoelectric element 24 is arranged such that opposing flat planar faces 26 a thereof contact adjacent flat planar faces 26 b of adjacently positioned piezoelectric elements 24 piezoelectric elements 24 are disposed within sleeve 28 such that a piston chamber 30 is defined at one end thereof each piezoelectric element 24 is a piezoelectric transistor pzt and is preferably fabricated of lead zirconate titanate other materials from which piezoelectric element 24 may be fabricated include but are not limited to quartz sio 2 tourmaline barium titanate batio 3 and various other barium and titanium salts organic and metallic tartrate salts and particularly sodium potassium tartrate nakc 4 h 4 o 6 may also be utilized piezoelectric stack 12 is actuated by the application of an electric potential thereacross the application of a voltage across each individual piezoelectric element 24 results in the structural deformation of the piezoelectric element 24 the greatest degree of deformation being in a longitudinal direction that is normal to the direction of the applied voltage field the resulting longitudinal deformation or strain induced in the direction normal to the applied voltage field is typically on the order of about one percent as a result of this strain actuator controller power conditioner 14 is incorporated to provide a voltage as a step function signal to actuate piezoelectric.