High-Displacement Piezoelectric Actuator Utilizing a Meander-Line Geometry—Part I: Experimental Characterization

A linear motion piezoelectric actuator having an unusually compact design has been developed that has relatively large displacement capabilities. The actuator is composed of a number of parallel bars of lead zirconate titanate (PZT) that are connected together in a meander line configuration so that they are mechanically in series and electrically in parallel. The polarity of the adjacent bars is arranged so that if a given bar expands under the applied voltage, the adjacent bars contract. Both ends of the meander line are clamped and the center of the meander line is the output where external loads are connected and where displacement relative to the clamped ends occurs. The absolute displacement of the output end of the meander line is the same as that of a single straight bar of the piezoelectric whose length is one half of that of the unwrapped meander line, assuming that the same voltage is applied to each structure. The prototype actuator using 22 bars of PZT, each 4 cm long, 3 mm wide, and 1.5 mm thick produced a displacement of 45 μ for an applied dc voltage of 500 V (electric field of about 3000 V/cm). These results as well as measurements of force output (about 0.3 N at 500 V) are in agreement with the predictions of an electromechanical model of the actuator which we have developed. This model predicted and measurements verified that stiffeners added to the basic meander line geometry significantly increased the force output (by a factor of three when two stiffeners were used) without affecting the displacement versus applied voltage relationship.