Design of a parallel kinematic MEMS XY nanopositioner

The purpose of this research is to design a novel parallel kinematic micro-electro-mechanical systems (MEMS) XY nanopositioner. It is challenging to design a MEMS XY positioner because of the limitations of fabrication, material property and actuation. The XY nanopositioner proposed in this manuscript is featured for decoupled motions, large stroke, compact size and large out-of-plane stiffness. This positioner includes three parts: thermal actuator, displacement amplifier and guide mechanism. The thermal actuator is applied to create a large electrothermal force for the in-plane motion. The lever based displacement amplifier is designed to increase the in-plane stroke. The symmetrical parallel guide mechanism is used to decouple the motions in the x and y directions while increasing the out-of-plane stiffness. Based on the Screw Theory, we derive an analytical model for the actuation and control of the stage. Furthermore, a Finite Element (FE) model is proposed to analyze the analytical model. By means of MEMS fabrication, the footprint of the XY nanopositioner is only 5 mm × 5 mm. However, the nanopositioner is capable of reaching a stroke of 83 μm × 83 μm. Compared with other designs, this parallel XY positioner has a large work space with a compact size.