Martin L. Culpepper

Screw Theory Based Methodology for the Deterministic Type Synthesis of Flexure Mechanisms

Flexure mechanism synthesis, however, is still a comparably difficult task. This paper aims at exploring a simple but systematic type synthesis methodology for general flexure mechanisms. The applied mathematical tool is reciprocal screw system theory in geometric form, and the proposed approach is an improvement of freedom and constraint topology (FACT), which is based on the FACT approach, combining with other methods including equivalent compliance mapping, set operation on building blocks, etc. As a result, it enables the type synthesis of flexure mechanisms simple, complete, and effective. What is more significant is that the proposed approach makes the unified type synthesis of both constraint-based and kinematics-based flexure mechanisms available. That is also the new contribution to the flexure de-sign.

Design of Contoured Microscale Thermomechanical Actuators

In this paper, we disclose how to contour the beams of microscale thermomechanical actuators (TMAs) in order to enhance the actuators thermal and mechanical performance. In this approach, we vary the cross-section of the heated beams over the length of the beams. Using this approach, the stored strain energy and axial stiffness of the beam may be modified to achieve an optimized force-displacement relationship. Examples are provided to show that in some designs: 1) the maximum achievable thermal strain of a driving beam may be increased by 29%, 2) actuator stroke may be increased by a factor of four, and 3) identical force or displacement characteristics may be achieved with a 90% reduction in power. This paper presents the theory and models used to predict the thermal and mechanical behavior of the actuator. The theory and models were used to create a deterministic link between the actuators design parameters and the actuators performance characteristics. The theory and models were combined within a design tool that is posted at http://pcsl.mit.edu. The tool has been used to generate performance plots that enable designers to: 1) understand the quantitative relationships between design parameters and performance and 2) rapidly converge upon first-pass design parameters.1695

Difference between bending and stretching moduli of single-walled carbon nanotubes that are modeled as an elastic tube

The authors show that an elastic tube model of a (5,5) carbon nanotube predicts stretching and bending moduli that differ by 19%. This is due to (1) differing energy storage mechanisms in each mode and (2) the inability of the tube model to capture these effects. Conventional tube models assume a common energy storage mechanism in stretching and bending. They show that energy is stored primarily through bond stretching/rotation and bond torsion/van der Waals interactions in stretching and bending, respectively. This knowledge underscores the need to use different moduli to predict stretching, bending, and combined bending and stretching when using the tube model.

Simulation of a carbon nanotube-based compliant parallel-guiding mechanism: A nanomechanical building block

The authors report the behavior of a nanoscale parallel-guiding mechanism wherein the compliant components are single-walled carbon nanotubes. Parallel-guiding mechanisms are often the building blocks of macro- and microscale mechanical systems. The authors present results that provide insight into the performance of a parallel-guiding mechanism for nanoscale devices. The device exhibits a range over 75% of the device size, i.e., 5.5nm, when actuated with 6.4nN. Below 3.6nN, displacements are due to bulk elastic bending of the nanotubes. Above 5.2nN, displacements are governed by the hingelike bending of kinks in the nanotubes. van der Waals forces are shown to cause direction-dependent behavior.

A multi-axis MEMS sensor with integrated carbon nanotube-based piezoresistors for nanonewton level force metrology.

This paper presents the design and fabrication of a multi-axis microelectromechanical system (MEMS) force sensor with integrated carbon nanotube (CNT)-based piezoresistive sensors. Through the use of proper CNT selection and sensor fabrication techniques, the performance of the CNT-based MEMS force sensor was increased by approximately two orders of magnitude as compared to current CNT-based sensor systems. The range and resolution of the force sensor were determined as 84 μN and 5.6 nN, respectively. The accuracy of the force sensor was measured to be better than 1% over the devices full range.

A Pseudo-Rigid-Body Model for Large Deflections of Fixed-Clamped Carbon Nanotubes

Carbon nanotubes (CNTs) may be used to create nanoscale compliant mechanisms that possess large ranges of motion relative to their device size. Many macroscale compliant mechanisms contain compliant elements that are subjected to fixed-clamped boundary conditions, indicating that they may be of value in nanoscale design. The combination of boundary conditions and large strains yield deformations at the tube ends and strain stiffening along the length of the tube, which are not observed in macroscale analogs. The large-deflection behavior of a fixedclamped CNT is not well-predicted by macroscale large-deflection beam bending models or truss models. Herein, we show that a pseudo-rigid-body model may be adapted to capture the strain stiffening behavior and, thereby, predict a CNT’s fixed-clamped behavior with less than 3% error from molecular simulations. The resulting pseudo-rigid-body model may be used to set initial design parameters for CNT-based compliant mechanisms. This removes the need for iterative, time-intensive molecular simulations during initial design phases. DOI: 10.1115/1.4001726

A surface diffusion model for Dip Pen Nanolithography line writing

Dip Pen Nanolithography is a direct write process that creates nanoscale dots and lines. Models typically predict dot and line size via assumption of constant ink flow rate from tip to substrate. This is appropriate for dot writing. It is however well-known, though models rarely reflect, that the ink flow rate depends upon writing speed during line writing. Herein, we explain the physical phenomenon that governs line writing and use this to model tip-substrate diffusion in line writing. We accurately predict (i) the increase in flow rate with writing speed and (ii) line width within 12.5%.

Type Synthesis Principle and Practice of Flexure Systems in the Framework of Screw Theory: Part I—General Methodology

The systematic methodologies involved in type synthesis of flexure systems are no doubt helpful to generate one and more high-performance precision machine designs at the stage of conceptual design with a rapid and effective way. This paper provides a systematic formulation of the type synthesis of parallel, serial, and hybrid flexure systems via a mapping from a geometric concept to physical entity. The whole type synthesis principle is built upon screw system theory and the geometric Freedom and Constraint Topology (FACT) approach, also combining with other concepts and methods including equivalent compliance mapping, building block etc, which enables the type synthesis of flexure systems deterministic, simple and practical. After that, Type synthesis procedure for various flexure systems are elaborated with examples. As a result, as many specified-DOF (Degree of Freedom) flexure systems as possible can be found and therefore pave the way for obtaining an optimal configuration.Copyright

Micromanufacturing: International research and development

Foreword Table of Contents List of Figures List of Tables Executive Summary 1. Introduction: Richard E. DeVor and Kornel F. Ehmann: Background and Scope Methodology Overview of the Report Format for this Report Acknowledgements 2. Design: Martin L. Culpepper and Thomas R. Kurfess Abstract The Approach Taken to Assess the State-of-the-Art in NLBMM Design Unique Requirements for the Design of NLBMM Parts, Processes and Equipment The Design Process and the Important Elements ofDesign of Y for NLBMM Products The State-of-the-Art and Gaps between Existing and Required Capabilities Summary and Conclusions References 3. Materials: David Bourell and Kamlakar Rajurkar: Abstract Materials for Micromanufacturing Materials Issues in Micromanufacturing Summary and Conclusions References 4. Processes: Kamlakar Rajurkar and Marc Madou: Abstract Micromanufacturing Processes and Equipment Micromanufacturing Issues Summary and Conclusions References 5. Metrology, Sensors and Control: Thomas R. Kurfess and Thom J. Hodgson: Abstract Introduction Summary and Conclusions References 6. Non-lithography Applications: Marc Madou: Abstract Applications ofNon-lithography Machining Flexible Manufacturing and Desktop Manufacturing MEMS Foundry Summary References 7. Business, Education, the Environment, and Other Issues: Thom J. Hodgson: Abstract Business Education Environment Government Policies APPENDICES : A. Panelist Biographies B. Questionnaire for Site Visits C. Site Reports-Asia: National Institute ofAdvanced Industrial Science and Technology (AIST) Asia Pacific Microsystems, Inc. (APM) FANUC, FA Hitachi Chemical R&D Center in Tsukuba ITRI - Mechanical Industry Research Laboratories (MIRL) ITRI - Nano Technology Research Center (NTRC) Instrument Technology Research Center (ITRC) Korean Advanced Institute of Science and Technology (KAIST) Korean Institute ofMachinery and Materials (KJMM) Kyocera Corporation Kyoto University Matsuura Machinery Corporation Metal Industries Research and Development Centre (MTRDC) Mitsubishi Electric Corporation (MEC) Nagoya University - Center for Cooperative Research in Advanced Science Nagoya University - Laboratory of Structure and Morphology Control Nagoya University - Department of Micro System Engineering National Cheng Kung University National Science Council National Taiwan University Olympus Corporate R&D Center RIKEN (The Institute of Physical & Chemical Research) Samsung Electro Mechanics Corp., R&D Center Sankyo Seiki Sansyu Finetool Co., Ltd Seiko Instruments Inc. (511) Seoul National University University of Electro Communications University of Tokyo I. I. S., The University of Tokyo Yonsei University D. Site Reports-Europe: BASELWORLD Robert Bosch, GmbH Ecole Polytechnique Federale De Lausanne (EPFL) Fraunhofer Institute - Manufacturing Engineering and Automation (IPA) Fraunhofer Institute - Production Systems and Design Technology (IPK) Fraunhofer Institute - Production and Laser Technology (IPT)/(ILT) Fraunhofer Institute - Reliability and Microintegration (IZM) Karlsruhe Research Center Kiocke Nanotechnik Kugler GmbH Laser Zentrum Hamiover e.V Institut fur Mikrotechnik Mainz GmbH (1MM) Philips Center for Industrial Technology (CFT) Swiss Federal Institute ofTechnology - Zurich (ETHZ) Technical University of Eindhoven Carl Zeiss Industrielle Messtechnik, GmbH Zumtobel E. Glossary.

Design of Contoured Thermomechanical Actuators and Pulsing Actuation to Enhance Dynamic Performance

This paper presents the concepts, models, and experimental validations of the geometric contouring method and a pulsing technique to enhance dynamic performance of micro thermomechanical actuators (μTMAs). For a typical TMA, contouring may improve its stroke, force, and speed performances by a factor of 4, 2.5, and 10, respectively. In the meantime, the required power for achieving the same performance is reduced by 40%. Herein, we show the following: 1) how to obtain marked dynamic and static performance from μTMAs; 2) how to model and optimize these improvements; and 3) how to use transient electrical command signals to augment these improvements. The utility and practical implementation of these techniques are illustrated via a case study on a stage from a three-axis optical scanner for a two-photon endomicroscope.