In Part II of this paper we demonstrate how to use freedom and constraint topology (FACT) to synthesize concepts for the multi-degree of freedom, parallel precision flexure systems that fall within the scope of Part I. Several examples are provided to demonstrate how the Principle of Complementary Topologies and geometric entities from Part I are (i) relevant to flexure system characteristics, (ii) used to visualize the possible layout of flexure constraints to achieve a desired motion and (iii) used to select redundant constraints. A synthesis process is presented, and then used to visualize and construct a flexure system concept with the requisite kinematic characteristics and redundant constraints that provide increased stiffness, load capacity, and symmetry. The output of the process is a flexure concept that would then be modeled and refined by existing modeling and analysis methods.

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Synthesis of multi-degree of freedom, parallel flexure system concepts via freedom and constraint topology (FACT). Part II: Practice

Author(s): Requicha, Ari | Abstract: Nanorobotics encompasses the design, fabrication, and programming of robots with overall dimensions below a few micrometers, and the programmable assembly of nanoscale objects. Nanorobots are quintessential nanoelectromechanical systems (NEMS) and raise all the important issues that must be addressed in NEMS design: sensing, actuation, control, communications, power, and interfacing across spatial scales and between the organic/inorganic and biotic/abiotic realms. Nanorobots are expected to have revolutionary applications in such areas as environmental monitoring and health care.This paper begins by discussing nanorobot construction, which is still at an embryonic stage. The emphasis is on nanomachines, an area which has seen a spate of rapid progress over the last few years. Nanoactuators will be essential components of future NEMS.The paper's focus then changes to nanoassembly by manipulation with scanning probe microscopes (SPMs), which is a relatively well established process for prototyping nanosystems. Prototyping of nanodevices and systems is important for design validation, parameter optimization and sensitivity studies. Nanomanipulation also has applications in repair and modification of nanostructures built by other means. High-throughput SPM manipulation may be achieved by using multitip arrays.Experimental results are presented which show that interactive SPM manipulation can be used to accurately and reliably position molecular-sized components. These can then be linked by chemical or physical means to form subassemblies, which in turn can be further manipulated. Applications in building wires, single-electron transistors, and nanowaveguides are presented.

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Nanorobots, NEMS, and Nanoassembly

This paper presents the design, kinematic and dynamic analysis, fabrication and characterization of a monolithic micro/nanopositioning three degrees-of-freedom (DOF) (XYθ) stage. The design of the proposed MEMS (micro-electro-mechanical system) stage is based on a parallel-kinematic mechanism (PKM) scheme that allows for translation in the XY plane and rotation about the Z axis, an increased motion range, and linear kinematics in the operating region (or work area) of the stage. The truss-like structure of the PKM results in higher modal frequencies by increasing the structural stiffness and reducing the moving mass of the stage. The stage is fabricated on a silicon-on-insulator (SOI) wafer using surface micromachining and deep reactive ion etching (DRIE) processes. Three sets of electrostatic linear comb drives jointly actuate the mechanism to produce motion in the X, Y and θ (rotation) directions. The fabricated stage provides a motion range of 18 μm and 1.72° at a driving voltage of 85 V. The resonant frequency of the stage under ambient conditions is 465 Hz. Additionally a high Q factor (∼66) is achieved from this parallel-kinematics mechanism design.

A SOI-MEMS-based 3-DOF planar parallel-kinematics nanopositioning stage

We present the constraint-based design of a novel parallel kinematic flexure mechanism that provides highly decoupled motions along the three translational directions (X, Y, and Z) and high stiffness along the three rotational directions (θx , θy , and θz ). The geometric decoupling ensures large motion range along each translational direction and enables integration with large-stroke ground-mounted linear actuators or generators, depending on the application. The proposed design, which is based on a systematic arrangement of multiple rigid stages and parallelogram flexure modules, is analyzed via non-linear finite element analysis. A proof-of-concept prototype of the flexure mechanism is fabricated to validate its large range and decoupled motion capability. The analyses as well as the hardware demonstrate an XYZ motion range of 10 mm × 10 mm × 10 mm. Over this motion range, the non-linear FEA predicts a cross-axis error of less than 3%, parasitic rotations less than 2 mrad, less than 4% lost motion, actuator isolation less than 1.5%, and no perceptible motion direction stiffness variation. Ongoing work includes non-linear closed-form analysis and experimental measurement of these error motion and stiffness characteristics.Copyright © 2011 by ASME

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An XYZ Parallel Kinematic Flexure Mechanism With Geometrically Decoupled Degrees of Freedom

The development of manufacturing tools and processes capable of precisely positioning and manipulating nanoscale components and materials is still in its embryonic stage. Microactuators are emerging as important tools capable of precisely positioning and manipulating nanoscale components and materials. This paper provides a summary of the state-of the-art in the design, fabrication, and application of microactuators for nanoscale manufacturing and assembly. Key characteristics and design models of electrothermal and electrostatic microactuators are described and compared. Specific design requirements for their functionality at the nanoscale are discussed. The results demonstrate the limitations of existing microactuator designs and key challenges associated with their design, modeling, and performance characterization for nanoscale positioning, assembly, and manipulation.

Emerging Challenges of Microactuators for Nanoscale Positioning, Assembly, and

This paper reviews the state-of-the-art of nanomanipulator concepts, designs and practices in research, prototyping and fabrication of nanodevices. Limitations of existing nanomanipulation systems in use have been examined including the device sizes of orders of magnitude too large for in situ applications and parallel applications in nanomanufacturing. Design strategies, mechanisms and practical solutions have been investigated for nanaomanipulation with multiple degrees of freedom, needed for manufacturing complex nanodevices and nanosystems. Both macro- and micro-scale nanomanipulator designs and practices are examined.

Zhenqi Zhu

Papers

Review of nanomanipulators for nanomanufacturing