Millimeter-sized nanomanipulator with sub-nanometer positioning resolution and large force output

Nanomanipulation in space-limited environments (e.g., inside a SEM (scanning electron microscope), and particularly in a TEM (transmission electron microscope)) requires small-sized nanomanipulators that are capable of producing sub-nanometer positioning resolutions and large output forces. This paper reports on a millimeter-sized MEMS (microelectromechanical systems) based nanomanipulator with a positioning resolution of 0.15 nm and a motion range of ± 2.55 µm. An amplification mechanism is employed to convert micrometer input displacements, generated by a conventional electrostatic comb-drive microactuator, into sub-nanometer output displacements. The device has a high load driving capability, driving a load as high as 98 µN without sacrificing positioning performance. Based on the pseudo-rigid-body approach, closed-form analytical models of the minification ratio and stiffness of the amplification mechanism are developed. Finite element simulation and testing results verify that the theoretical models are valid with an error smaller than 6.2% and that the mechanism has a high linearity (± 2.4%). The amplification mechanism and analytical models have general applicability to other MEMS transducer designs. A capacitive displacement sensor is integrated for detecting input displacements that are converted into output displacements via the minimization ratio, allowing closed-loop controlled nanomanipulation. The MEMS-based nanomanipulators are applicable to the characterization/manipulation of nanomaterials and construction of nanodevices. Corrections were made to this article on 29 August 2007 (in the Abstract and sections 3.2.3 and 5.2). The corrected electronic version is identical to the print version.