Diamagnetically levitated nano positioners with large range and multiple degrees of freedom

Abstract

Precision positioning stages are indispensable in many branches of science and engineering, where they are employed for imaging, manipulation, fabrication, and material characterization. Compact, multi-degree-of-freedom stages with a large dynamic range are especially desirable since they improve the throughput, versatility in manipulation, and ease of integration with other instruments. However, most positioning technologies demand large compromises be made on one or more of these fronts. This work describes compact diamagnetically levitated nano-positioners to achieve large-range and high precision six-degrees-of-freedom (DOF) positioning. The first part of the thesis describes the design and modeling of a diamagnetically levitated multi-DOF actuator. The actuator comprises a levitating magnetic stage sandwiched between two current-carrying traces. The levitation height of the magnetic stage above the pyrolytic graphite plate was derived by modeling the diamagnetic force. Next, an analytical model was devised to evaluate the electromagnetic forces, torques, and trap stiffness. Subsequently, the developed model was used to demonstrate that dual-sided actuation enables trapping a magnetic stage in 3-dimensions (3D), with independent control of the trap stiffness about two axes and independent application of forces in 3D and torques about two axes. Next, the maximum loads that can be generated using the dual-sided actuation were evaluated. Finally, the maximum possible trap stiffness along all the 3-axis was determined. Although the proposed actuator has multiple degrees of freedom, it cannot be rotated about the Z-axis, and further, it has a limited out-of-plane motion range. The second part of the thesis discusses the design of two novel six-axis positioners based on dual sided-actuation that addresses the limitations of the actuator proposed in the first part...