Utilizing Microelectromechanical Systems (MEMS) Micro-Shutter Designs for Adaptive Coded Aperture Imaging (ACAI) Technologies

The Air Force has long relied on surveillance for intelligence and strategic purposes. Most surveillance systems rely on a lensing system to acquire their images, most of which are in either the visible or infrared wavelengths. Because lensing systems can be expensive, obtrusive, or hard to maintain, researchers have designed adaptive coded aperture imaging (ACAI) as a replacement system. Coded aperture imaging (CAI) has been used in both the astronomical and medical communities for years due to its ability to image light at short wavelengths and thus replacing conventional lenses. Where CAI is limited, researchers have discovered that adaptive coded aperture imaging can recover what is lost. ACAI uses a reconfigurable coding mask and digital signal processing to recover the original scene from the detector. In this effort, a prototype of MEMS microshutters has been designed and fabricated onto a 3 mm x 3 mm square of silicon substrate using the PolyMUMPS™ process. This prototype is a line-drivable array using thin flaps of polysilicon to cover and uncover an 8 x 8 array of 20 µm apertures and is the first known microshutter array to incorporate a line-drivable array driven by physical actuation. A characterization of the micro-shutters to include mechanical, electrical and optical properties is provided. This prototype, its actuation scheme, and other designs for individual microshutters have been modeled and studied for feasibility purposes, and this revealed that the actuation scheme failed in its design due to oversights in the design process and lack of space for each gear actuator. Because of conformality in the PolyMUMPS™ process, none of the microshutters could physically move, but optical analysis with a 632 nm HeNe laser revealed that they will not undergo upward deflection when exposed to irradiance sources of less than 0.5 W. The microshutters were also designed to transmit less than 20% of irradiated light and initial testing confirmed that fact. In addition, microshutters fabricated from an Al-Au alloy on a quartz wafer were characterized and showed that wedge-style shutters are functional, if not ideal for an ACAI array

The middeck 0-gravity dynamics experiment

The Middeck 0-Gravity Dynamics Experiment (MODE), flown onboard the Shuttle STS-48 Mission, consists of three major elements: the Experiment Support Module, a dynamics test bed providing computer experiment control, analog signal conditioning, power conditioning, an operator interface consisting of a keypad and display, experiment electrical and thermal control, and archival data storage: the Fluid Test Article assembly, used to investigate the dynamics of fluid-structure interaction in 0-gravity; and the Structural Test Article for investigating the open-loop dynamics of structures in 0-gravity. Deployable, erectable, and rotary modules were assembled to form three one- and two-dimensional structures, in which variations in bracing wire and rotary joint preload could be introduced. Change in linear modal parameters as well as the change in nonlinear nature of the response is examined. Trends in modal parameters are presented as a function of force amplitude, joint preload, and ambient gravity. An experimental study of the lateral slosh behavior of contained fluids is also presented. A comparison of the measured earth and space results identifies and highlights the effects of gravity on the linear and nonlinear slosh behavior of these fluids

Flexible structure control laboratory development and technology demonstration

An experimental structure is described which was constructed to demonstrate and validate recent emerging technologies in the active control and identification of large flexible space structures. The configuration consists of a large, 20 foot diameter antenna-like flexible structure in the horizontal plane with a gimballed central hub, a flexible feed-boom assembly hanging from the hub, and 12 flexible ribs radiating outward. Fourteen electrodynamic force actuators mounted to the hub and to the individual ribs provide the means to excite the structure and exert control forces. Thirty permanently mounted sensors, including optical encoders and analog induction devices provide measurements of structural response at widely distributed points. An experimental remote optical sensor provides sixteen additional sensing channels. A computer samples the sensors, computes the control updates and sends commands to the actuators in real time, while simultaneously displaying selected outputs on a graphics terminal and saving them in memory. Several control experiments were conducted thus far and are documented. These include implementation of distributed parameter system control, model reference adaptive control, and static shape control. These experiments have demonstrated the successful implementation of state-of-the-art control approaches using actual hardware

Nanotribology and Nanomechanics of Thin Films Including Material Characterization, Mechanical Wear, Adhesion and Lubrication

The present work is dedicated to addressing nanotribological issues of ultra-thin (sub-10 nm) films at contacting interfaces. In devices such as micro-electro-mechanical systems (MEMS), thin films are deposited for specific functions. In some occasions, mechanical durability of the thin films is also important. Magnetic storage hard disk drives (HDD) are a good example where nanotribology at the head-disk interface (HDI) is extremely important. Especially in recent years, where the areal density increases exponentially and the write/read head has been brought as close to as less than 10 nm to the disk surface. As a result, direct contact is possible to occur at such small distance and such unfavorable contact will cause mechanical wear and demagnetization. Nanometer thick diamond like carbon (DLC) and lubricant films provide important protection and study of their failure mechanisms is necessary. The present thesis has conducted research to understand the nanotribology of thin films in the multilayered system used in HDDs. The majority of the work is measurement of the nanomechanical and nanotribological properties of the solid thin films with thickness of less than 20 nm. A method combining finite element analysis (FEA) and nanoindentation was proposed to extract nanomechanical properties from nanoindentation data for multilayered samples. A highly sensitive nanomechanical transducer was introduced to perform sub-5 nm shallow nanoindentation experiments on thin films deposited at different conditions. To study the tribological performance of DLC films at high temperatures up to 300 °C, the present work performs nanoscratch and nanowear tests on a 3-nm thick DLC film. The results show the wear rate of DLC films begin to increase abruptly at around 200°C and this degradation of wear resistance is irreversible. The present thesis also proposes a mathematical model to quantitatively predict the hydrodynamic lubrication effects of the molecularly thin lubricant between the head and the disk surfaces. After considering the nanorheological behavior of the lubricant, the model is able to make predictions of contacting forces and pressures and explain the tribological role of the lubricant in terms of continuum mechanics. Lastly, present thesis proposed a model considering Van der Waals forces between lubricants on the disk and on the head. The proposed model provides stricter criterion for onset of adhesion induced lubricant-transfer between the two wet surfaces and is in better agreement with Molecular Dynamics simulations than conventional models. In summary, the findings above center about nanomechanics and nanotribology at the interfaces of the magnetic storage hard disk. However, these findings can also extend their applications to other MEMS devices where tribology issues are of important concerns. The shallow nanoindentaton instrument and FEA-based characterization method can be applicable any other solid thin films. The high-temperature tribological properties of a ultra-thin DLC films utilize a unique test rig but the findings are generally instructive in understanding behaviors of DLC at high temperature. The nano-lubrication model for a lubricated single asperity can be an addition of current contact mechanics which usually neglects the presence of lubricants

Nanotribology and Nanomechanics of Thin Films Including Material Characterization, Mechanical Wear, Adhesion and Lubrication

The present work is dedicated to addressing nanotribological issues of ultra-thin (sub-10 nm) films at contacting interfaces. In devices such as micro-electro-mechanical systems (MEMS), thin films are deposited for specific functions. In some occasions, mechanical durability of the thin films is also important. Magnetic storage hard disk drives (HDD) are a good example where nanotribology at the head-disk interface (HDI) is extremely important. Especially in recent years, where the areal density increases exponentially and the write/read head has been brought as close to as less than 10 nm to the disk surface. As a result, direct contact is possible to occur at such small distance and such unfavorable contact will cause mechanical wear and demagnetization. Nanometer thick diamond like carbon (DLC) and lubricant films provide important protection and study of their failure mechanisms is necessary. The present thesis has conducted research to understand the nanotribology of thin films in the multilayered system used in HDDs. The majority of the work is measurement of the nanomechanical and nanotribological properties of the solid thin films with thickness of less than 20 nm. A method combining finite element analysis (FEA) and nanoindentation was proposed to extract nanomechanical properties from nanoindentation data for multilayered samples. A highly sensitive nanomechanical transducer was introduced to perform sub-5 nm shallow nanoindentation experiments on thin films deposited at different conditions. To study the tribological performance of DLC films at high temperatures up to 300 °C, the present work performs nanoscratch and nanowear tests on a 3-nm thick DLC film. The results show the wear rate of DLC films begin to increase abruptly at around 200°C and this degradation of wear resistance is irreversible. The present thesis also proposes a mathematical model to quantitatively predict the hydrodynamic lubrication effects of the molecularly thin lubricant between the head and the disk surfaces. After considering the nanorheological behavior of the lubricant, the model is able to make predictions of contacting forces and pressures and explain the tribological role of the lubricant in terms of continuum mechanics. Lastly, present thesis proposed a model considering Van der Waals forces between lubricants on the disk and on the head. The proposed model provides stricter criterion for onset of adhesion induced lubricant-transfer between the two wet surfaces and is in better agreement with Molecular Dynamics simulations than conventional models. In summary, the findings above center about nanomechanics and nanotribology at the interfaces of the magnetic storage hard disk. However, these findings can also extend their applications to other MEMS devices where tribology issues are of important concerns. The shallow nanoindentaton instrument and FEA-based characterization method can be applicable any other solid thin films. The high-temperature tribological properties of a ultra-thin DLC films utilize a unique test rig but the findings are generally instructive in understanding behaviors of DLC at high temperature. The nano-lubrication model for a lubricated single asperity can be an addition of current contact mechanics which usually neglects the presence of lubricants

A Rapidly Reconfigurable Robotics Workcell and Its Applictions for Tissue Engineering

This article describes the development of a component-based technology robot system that can be rapidly configured to perform a specific manufacturing task. The system is conceived with standard and inter-operable components including actuator modules, rigid link connectors and tools that can be assembled into robots with arbitrary geometry and degrees of freedom. The reconfigurable "plug-and-play" robot kinematic and dynamic modeling algorithms are developed. These algorithms are the basis for the control and simulation of reconfigurable robots. The concept of robot configuration optimization is introduced for the effective use of the rapidly reconfigurable robots. Control and communications of the workcell components are facilitated by a workcell-wide TCP/IP network and device level CAN-bus networks. An object-oriented simulation and visualization software for the reconfigurable robot is developed based on Windows NT. Prototypes of the robot systems configured to perform 3D contour following task and the positioning task are constructed and demonstrated. Applications of such systems for biomedical tissue scaffold fabrication are considered.Singapore-MIT Alliance (SMA

Department of Computer Science Activity 1998-2004

This report summarizes much of the research and teaching activity of the Department of Computer Science at Dartmouth College between late 1998 and late 2004. The material for this report was collected as part of the final report for NSF Institutional Infrastructure award EIA-9802068, which funded equipment and technical staff during that six-year period. This equipment and staff supported essentially all of the department\u27s research activity during that period

NASA Tech Briefs, November 2011

The topics include: 1) Flight Test Results from the Rake Airflow Gage Experiment on the F-15B; 2) Telemetry and Science Data Software System; 3) CropEx Web-Based Agricultural Monitoring and Decision Support; 4) High-Performance Data Analysis Tools for Sun-Earth Connection Missions; 5) Experiment in Onboard Synthetic Aperture Radar Data Processing; 6) Microfabrication of a High-Throughput Nanochannel Delivery/Filtration System; 7) Improved Design and Fabrication of Hydrated-Salt Pills; 8) Monolithic Flexure Pre-Stressed Ultrasonic Horns; 9) Cryogenic Quenching Process for Electronic Part Screening; 10) Broadband Via-Less Microwave Crossover Using Microstrip-CPW Transitions; 11) Wheel-Based Ice Sensors for Road Vehicles; 12) G-DYN Multibody Dynamics Engine; 13) Multibody Simulation Software Testbed for Small-Body Exploration and Sampling; 14) Propulsive Reaction Control System Model; 15) Licklider Transmission Protocol Implementation; 16) Core Recursive Hierarchical Image Segmentation; 17) Two-Stage Centrifugal Fan; 18) Combined Structural and Trajectory Control of Variable-Geometry Planetary Entry Systems; 19) Pressure Regulator With Internal Ejector Circulation Pump, Flow and Pressure Measurement Porting, and Fuel Cell System Integration Options; 20) Temperature-Sensitive Coating Sensor Based on Hematite; 21) Standardization of a Volumetric Displacement Measurement for Two-Body Abrasion Scratch Test Data Analysis; 22) Detection of Carbon Monoxide Using Polymer-Carbon Composite Films; 23) Substituted Quaternary Ammonium Salts Improve Low-Temperature Performance of Double-Layer Capacitors; 24) Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer; 25) Integrated Lens Antennas for Multi-Pixel Receivers; 26) 180-GHz Interferometric Imager; 27) Maturation of Structural Health Management Systems for Solid Rocket Motors; 28) Validating Phasing and Geometry of Large Focal Plane Arrays; 29) Transverse Pupil Shifts for Adaptive Optics Non-Common Path Calibration; 30) Qualification of Fiber Optic Cables for Martian Extreme Temperature Environments; 31) Solid-State Spectral Light Source System; 32) Multiple-Event, Single-Photon Counting Imaging Sensor; 33) Surface Modeling to Support Small-Body Spacecraft Exploration and Proximity Operations; and 34) Achieving Exact and Constant Turnaround Ratio in a DDS-Based Coherent Transponder

A microgripper for single cell manipulation

This thesis presents the development of an electrothermally actuated microgripper for the manipulation of cells and other biological particles. The microgripper has been fabricated using a combination of surface and bulk micromachining techniques in a three mask process. All of the fabrication details have been chosen to enable a tri-layer, polymer (SU8) - metal (Au) - polymer (SU8), membrane to be released from the substrate stress free and without the need for sacrificial layers. An actuator design, which completely eliminates the parasitic resistance of the cold arm, is presented. When compared to standard U-shaped actuators, it improves the thermal efficiency threefold. This enables larger displacements at lower voltages and temperatures. The microgripper is demonstrated in three different configurations: normally open mode, normally closed mode, and normally open/closed mode. It has-been modelled using two coupled analytical models - electrothermal and thermomechanical - which have been custom developed for this application. Unlike previously reported models, the electrothermal model presented here includes the heat exchange between hot and cold arms of the actuators that are separated by a small air gap. A detailed electrothermomechanical characterisation of selected devices has permitted the validation of the models (also performed using finite element analysis) and the assessment of device performance. The device testing includes electrical, deflection, and temperature measurements using infrared (IR) thermography, its use in polymeric actuators reported here for the first time. Successful manipulation experiments have been conducted in both air and liquid environments. Manipulation of live cells (mice oocytes) in a standard biomanipulation station has validated the microgripper as a complementary and unique tool for the single cell experiments that are to be conducted by future generations of biologists in the areas of human reproduction and stem cell research