Design of three degrees-of-freedom motion stage for micro manipulation

Abstract

A miniaturized translational motion stage has potentials to provide not only performances equivalent to conventional motion stages, but also additional features from its small form factor and low cost. These properties can be utilized in applications requiring a small space such as a vacuum chamber in a scanning electron microscopy (SEM), where hidden surface can decrease by manipulating objects to measure. However, existing miniaturized motion stages still have several cm3 level volumes and provide simple operations.

In this dissertation, Micro-electro-mechanical systems (MEMS)-based motion stages are utilized to replace a miniaturized motion stage for micro-scale manipulation and possible applications. However, most MEMS fabrication methods remain in monolithic fabrication methods and a lot of MEMS based multiple degrees-of-freedom (DOFs) motion stage also remain for in-plane motions. In this dissertation, a nested structure based on a serial kinematic mechanism is implemented in order to overcome these constraints and implement out-of-plane motion, where one independent stage is embedded into the other individual stage with additional features for structurally and electrically isolations among the engaged stages. MEMS actuators and displacement amplifiers are also investigated for reasonable performance.

3-axis motions are divided into two in-plane motions and one out-of-plane motion; an in-plane 1 DOF motion stage (called an X-stage) and one out-of-plane 1 DOF motion stage (called a Z-stage) are designed and characterized experimentally. Based on the two stages, the XY-stage is designed by merging one X-stage into the motion platform of the other X-stage with a different orientation (called an XY-stage). With this nested approach, the fabricated XY-stage demonstrated in-plane motions larger than 50 µm with ignorable coupled motion errors. Based on this nested approach, the 3-axis motion stage is also implemented by utilizing the nested structure twice; integrating the Z-stage with the motion platform of the XY-stage (called an XYZ-stage). The XYZ-stage demonstrated out-of-plane motions about 23 µm as well as the in-plane motions.

Two presented motion stages have been utilized in the manipulation of micro-scale object by the cooperation of the two XY-stages inside a SEM chamber. The large motion platform of the X-stage is also utilized in a parallel plate type rheometer to measure the material properties of viscoelastic materials.