A Magnetic-Actuator Based Planar Nano-Positioning System

Magnetically actuated nano-positioning systems possess several advantages, including linearity in actuation, large positioning range and the possibility of multi-axis collocated actuation. This paper presents a planar nano-positioning system comprising an array of conductive meanders suspended by conductive compliant elements over a checkerboard of permanent magnets. Two distinct designs are reported, one for one-axis positioning and another for two-axis positioning. Such stages enable achieving high positioning speed and multi-axis in-plane actuation without affecting the achievable actuation gain. Theoretical models are proposed for the estimation of magnetic force and stiffness, and for the dynamic response of the positioner. These models are compared with the results of finite element analysis (FEA). The theoretical stiffnesses are shown to agree with the FEA results to within 2.9% and the natural frequencies are shown to agree to within 8.2%. Finally, a prototype of the single-axis positioner is fabricated and shown to track a commanded waveform of amplitude 200μm with good accuracy and negligible cross-axis motion. It is also shown to track a 50nm staircase signal with 5nm RMS resolution. The experimentally obtained natural frequency, estimated from the step-response, is shown to agree with the FEA results to be within 10.8%.