Piezoactuator-integrated monolithic microstage with six degrees of freedom

In comparison with miniature XY-stages in term of driving methods: electrostatic, electromagnetic and piezoelectric actuators, the piezoelectric actuators have high area efficiency but no machinability by conventional microfabrication techniques. In this paper we have proposed the novel fabrication method of a double-layered piezo-stack actuator made from a monolithic PZT plate based on a planar fabrication method, and integrated the actuators into an XYZ-stage with six degrees of freedom, i.e., X, Y, Z, theta(x), theta(y) and theta(z) directions. The stacked piezoactuators were formed on both sides of the PZT plate. The double stacked-piezoactuators, which are arranged around the stage, can stretch in plane or bend to Z-direction. The fabrication method includes dicing, electroplating, and laser machining. After making grooves by dicing, metal electroplating was performed and buried Ni into the grooves, which was done on both sides of the PZT plate. After polishing the surface, metal electrodes were formed on an insulating photosensitive polyimide layer. Finally, the complete structure was defined by laser machining. The test results show that the X-direction displacement of the actuation arms was about 2 mu m when 40 V was applied to both of double-layered piezo-stacked actuators. The Z-direction displacement of the actuation beam was about 2 mu m when 40 V was only applied to one stacked actuator. These results show the possibility of the microstage with six degrees of freedom. (C) 2005 Elsevier B.V. All rights reserved.