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Articles 31 - 60 of 64

Full-Text Articles in Electro-Mechanical Systems

Characterization Of Intercalated Graphite Fibers For Microelectromechanical Systems (Mems) Applications, Bryan W. Winningham Mar 2007

Characterization Of Intercalated Graphite Fibers For Microelectromechanical Systems (Mems) Applications, Bryan W. Winningham

Theses and Dissertations

Research was accomplished to characterize the electrical and physical characteristic changes of the Thornel® P-100 carbon fiber and five variants when intercalated with 96% sulfuric acid and incorporated the use of Microelectromechanical Systems (MEMS) structures for testing purposes. The five fiber variants were oxidized in 1 M nitric acid at 0.5 A for 30 seconds, 1 and 2 minutes, the last two samples were detreated at 1150 °C for one hour prior to the nitric acid treatment. The fibers were mounted onto a MEMS die, placed into a chip carrier, sulfuric acid added, the chip carrier sealed and testing accomplished. …


Toward A Flying Mems Robot, Nathan E. Glauvitz Mar 2007

Toward A Flying Mems Robot, Nathan E. Glauvitz

Theses and Dissertations

The work in this thesis includes the design, modeling, and testing of motors and rotor blades to be used on a millimeter-scale helicopter style flying micro air vehicle (MAV). Three different types of motor designs were developed and tested, which included circular scratch drives, electrostatic motors, and comb drive resonators. Six different rotor designs were tested; five used residual stress while one design used photoresist to act as a hinge to achieve rotor blade deflection. Two key parameters of performance were used to evaluate the motor and rotor blade designs: the frequency of motor rotation and the angle of deflection …


Characterization Of Stress In Gan-On-Sapphire Microelectromechanical Systems (Mems) Structures Using Micro-Raman Spectroscopy, Francisco E. Parada Mar 2006

Characterization Of Stress In Gan-On-Sapphire Microelectromechanical Systems (Mems) Structures Using Micro-Raman Spectroscopy, Francisco E. Parada

Theses and Dissertations

Micro-Raman (µRaman) spectroscopy is an efficient, non-destructive technique widely used to determine the quality of semiconductor materials and microelectromechanical systems. This work characterizes the stress distribution in wurtzite gallium nitride grown on c-plane sapphire substrates by molecular beam epitaxy. This wide bandgap semiconductor material is being considered by the Air Force Research Laboratory for the fabrication of shock-hardened MEMS accelerometers. µRaman spectroscopy is particularly useful for stress characterization because of its ability to measure the spectral shifts in Raman peaks in a material, and correlate those shifts to stress and strain. The spectral peak shift as a function of stress, …


Microelectromechanical Systems (Mems) Interrupter For Safe And Arm Devices, Steven S. Mink Mar 2006

Microelectromechanical Systems (Mems) Interrupter For Safe And Arm Devices, Steven S. Mink

Theses and Dissertations

This thesis addresses the development of a new micro-scale interrupter mechanism for a safe and arm device used in modern weapon systems. The interrupter mechanism often consists of a physical barrier that prevents an initial source of energy, in an explosive train, from being transferred to subsequent charges. In general, when the physical barrier is removed, the weapon is considered armed, and the charge is allowed to propagate. Several issues facing current safe and arm devices systems are the shrinking industrial base for manufacturing these devices and the desire for modern safe and arm devices to be compatible with next …


Power-Scavenging Mems Robots, Daniel J. Denninghoff Mar 2006

Power-Scavenging Mems Robots, Daniel J. Denninghoff

Theses and Dissertations

This thesis includes the design, modeling, and testing of novel, power-scavenging, biologically inspired MEMS microrobots. Over one hundred 500-μm and 990-μm microrobots with two, four, and eight wings were designed, fabricated, characterized. These microrobots constitute the smallest documented attempt at powered flight. Each microrobot wing is comprised of downward-deflecting, laser-powered thermal actuators made of gold and polysilicon; the microrobots were fabricated in PolyMUMPs® (Polysilicon Multi-User MEMS Processes). Characterization results of the microrobots illustrate how wing-tip deflection can be maximized by optimizing the gold-topolysilicon ratio as well as the dimensions of the actuator-wings. From these results, an optimum actuator-wing configuration was …


Protein Impregnated Polymer (Pip) Film Infrared Sensor Using Suspended Microelectromechanical Systems (Mems) Pixels, Tetsuo Kaieda Sep 2005

Protein Impregnated Polymer (Pip) Film Infrared Sensor Using Suspended Microelectromechanical Systems (Mems) Pixels, Tetsuo Kaieda

Theses and Dissertations

The Air Force Research Laboratory Materials and Manufacturing Directorate have developed a novel protein impregnated polymer (PIP) suspension that changes resistivity as a function of absorbed infrared radiation. Due to this property, the PIP is a potential material for use as an uncooled bolometer, or thermal sensor. In this research, a thermally-isolated pixel design, sensor characterization methods, and sensor fabrication and processing steps were developed. To create a microbolometer, the PIP was applied to two prototype micro-electro-mechanical systems (MEMS) surface micro-machined structures. The first is a raised cantilever pixel array that uses residual stress polysilicon and metal film arms to …


Insulator Charging In Rf Mems Capacitive Switches, Jay F. Kucko Jun 2005

Insulator Charging In Rf Mems Capacitive Switches, Jay F. Kucko

Theses and Dissertations

While capacitive radio frequency microelectromechanical (RF MEM) switches are poised to provide a low cost, high isolation, low power alternative to current RF switch technologies, there are still reliability issues limiting switch lifetime. Previous research identified insulator charging as a primary cause of switch failure. Changes in switch pull-in and release voltages were measured to provide insight into the mechanisms responsible for charging and switch failure. A spatial and temporal dependent model was developed to describe silicon nitride's time-dependent charging as a function of applied bias. This model was verified by applying constant biases to metal-silicon nitride-silicon capacitors and tracking …


Using Multiple Mems Imus To Form A Distributed Inertial Measurement Unit, Ryan D. Hanson Mar 2005

Using Multiple Mems Imus To Form A Distributed Inertial Measurement Unit, Ryan D. Hanson

Theses and Dissertations

MEMS IMUs are readily available in quantity and have extraordinary advantages over conventional IMUs in size, weight, cost, and power consumption. However, the poor performance of MEMS IMUs limits their use in more demanding military applications. It is desired to use multiple distributed MEMS IMUs to simulate the performance of a single, more costly IMU, using the theory behind Gyro-Free IMUs. A Gyro-Free IMU (GF-IMU) uses a configuration of accelerometers only to measure the three accelerations and three angular rotations of a rigid body in 3-D space. Theoretically, almost any configuration of six distributed accelerometers yields sufficient measurements to solve …


Head Tracking For 3d Audio Using A Gps-Aided Mems Imu, Jacque M. Joffrion Mar 2005

Head Tracking For 3d Audio Using A Gps-Aided Mems Imu, Jacque M. Joffrion

Theses and Dissertations

Audio systems have been developed which use stereo headphones to project sound in three dimensions. When using these 3D audio systems, audio cues sound like they are originating from a particular direction. There is a desire to apply 3D audio to general aviation applications, such as projecting control tower transmissions in the direction of the tower or providing an audio orientation cue for VFR pilots who find themselves in emergency zero-visibility conditions. 3D audio systems, however, require real-time knowledge of the pilot's head orientation in order to be effective. This research describes the development and testing of a low-cost head …


Detection Of Residual Stress In Sic Mems Using Μ-Raman Spectroscopy, John C. Zingarelli Mar 2005

Detection Of Residual Stress In Sic Mems Using Μ-Raman Spectroscopy, John C. Zingarelli

Theses and Dissertations

Micro-Raman (µ-Raman) spectroscopy is used to measure residual stress in two silicon carbide (SiC) poly-types: single-crystal, hexagonally symmetric 6H-SiC, and polycrystalline, cubic 3C-SiC thin films deposited on Si substrates. Both are used in micro-electrical-mechanical systems (MEMS) devices. By employing an incorporated piezoelectric stage with submicron positioning capabilities along with the Raman spectral acquisition, spatial scans are performed to reveal areas in the 6H-SiC MEMS structures that contain residual stress. Shifts in the transverse optical (TO) Stokes peaks of up to 2 cm-1 are correlated to the material strain induced by the MEMS fabrication process through the development of phonon …


Electrostatic Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches With Metal Alloy Electric Contacts, Ronald A. Coutu Jr. Sep 2004

Electrostatic Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches With Metal Alloy Electric Contacts, Ronald A. Coutu Jr.

Theses and Dissertations

RF MEMS switches are paramount in importance for improving current and enabling future USAF RF systems. Electrostatic micro-switches are ideal for RF applications because of their superior performance and low power consumption. The primary failure mechanisms for micro-switches with gold contacts are becoming stuck closed and increased contact resistance with increasing switch cycles. This dissertation reports on the design, fabrication, and testing of micro-switches with sputtered bi-metallic (i.e., gold (Au)-on-Au-(6.3at%)platinum (Pt)), binary alloy (i.e., Au-(3.7at%)palladium (Pd) and Au-(6.3at%)Pt), and ternary alloy (i.e., Au-(5at%)Pt-(0.5at%)copper (Cu)) contact metals. Performance was evaluated, in-part, using measured contact resistance and lifetime results. The micro-switches with …


A Tightly-Coupled Ins/Gps Integration Using A Mems Imu, Jonathan M. Neu Sep 2004

A Tightly-Coupled Ins/Gps Integration Using A Mems Imu, Jonathan M. Neu

Theses and Dissertations

Micro-Electro-Mechanical Systems (MEMS) technology holds great promise for future navigation systems because of the reduced size and cost of MEMS inertial sensors relative to conventional devices. Current MEMS devices are much less accurate than standard inertial sensors, but they can still be useful. In this thesis, data was recorded from an inexpensive MEMS inertial measurement unit and integrated with GPS measurements using a tightly-coupled Kalman filter. The overall goal of this research is to investigate the usefulness of MEMS sensors for a small, real-time, low-cost INS/GPS integration. A golf cart was used to collect dynamic data, along with a commercial …


Thin Film Encapsulation Of Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches, Eric D. Marsh Mar 2004

Thin Film Encapsulation Of Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches, Eric D. Marsh

Theses and Dissertations

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission …


Demonstrating Optothermal Actuators For An Autonomous Mems Microrobot, Francis R. Szabo Mar 2004

Demonstrating Optothermal Actuators For An Autonomous Mems Microrobot, Francis R. Szabo

Theses and Dissertations

There are numerous applications for microrobots which are beneficial to the Air Force. However, the microrobotics field is still in its infancy, and will require extensive basic research before these applications can be fielded. The biggest hurdle to be solved, in order to create autonomous microrobots, is generating power for their actuator engines. Most present actuators require orders of magnitude more power than is presently available from micropower sources. To enable smaller microrobots, this research proposed a simplified power concept that eliminates the need for on-board power supplies and control circuitry by using actuators powered wirelessly from the environment. This …


Mechanical Computing In Microelectromechanical Systems (Mems), Kenneth C. Bradley Mar 2003

Mechanical Computing In Microelectromechanical Systems (Mems), Kenneth C. Bradley

Theses and Dissertations

Mechanical computing devices in polysilicon-based microelectromechanical systems (MEMS) were designed with the goal of developing computing devices for harsh environments, such as those with high dose radiation and high temperatures, as well as devices that may be able to interface with molecular or biological computer systems. The devices that were designed include both analog and digital computing devices. The analog devices include integrators, differentials (summers), multipliers, and those that perform trigonometric functions. The digital devices that were designed are inverters, NAND, NOR, and XOR logic gates. Analog-to-digital (A-to-D) and digital-to-analog (D-to-A) converters were also designed. The designs were submitted to …


The Effects Of Ionizing Radiation On Microelectromechanical Systems (Mems) Actuators: Electrostatic, Electrothermal, And Residual Stress, Jared R. Caffey Mar 2003

The Effects Of Ionizing Radiation On Microelectromechanical Systems (Mems) Actuators: Electrostatic, Electrothermal, And Residual Stress, Jared R. Caffey

Theses and Dissertations

The effects of ionizing radiation on the operation of polysilicon mmicroelectromechanical system (MEMS) electrostatic actuators, electrothermal actuators, and residual stress cantilevers were examined. Pre-irradiation, in-situ, and post-irradiation measurements were taken for the electrosatic and electrothermal actuators. The residual stress cantilevers were characterized before and after irradiation. All devices were irradiated to a total ionizing does of 1 megarad(Si) using both the Air Force Research Laboratory's low energy X-ray source and Co-60 gamma source.


Characterization Of Residual Stress In Microelectromechanical Systems (Mems) Devices Using Raman Spectroscopy, Lavern A. Starman Apr 2002

Characterization Of Residual Stress In Microelectromechanical Systems (Mems) Devices Using Raman Spectroscopy, Lavern A. Starman

Theses and Dissertations

Due to the small scale of MEMS devices, the inherent residual stresses during the deposition processes can affect the functionality and reliability of the fabricated devices. Residual stress often causes device failure due to curling, buckling, or fracture. Currently, few techniques are available to measure the residual stress in MEMS devices. In this dissertation, Raman spectroscopy is used to measure and monitor the residual and induced stresses in MUMPs polysilicon MEMS devices. Raman spectroscopy was selected since it is nondestructive, fast, and provides potential in situ stress monitoring. Raman spectroscopy scans on unreleased and released MEMS fixed-fixed beams, cantilevers, and …


Fabrication Techniques For Iii-V Micro-Opto-Electro-Mechanical Systems, Jeremy A. Raley Mar 2002

Fabrication Techniques For Iii-V Micro-Opto-Electro-Mechanical Systems, Jeremy A. Raley

Theses and Dissertations

This thesis studies selective etching techniques for the development of AlxGa1-xAs micro-opto-electro-mechanical systems (MOEMS). New MEMS technology based on materials such as AlxGa1-xAs enables the development of micro-systems with embedded active micro-optical devices. Tunable micro-lasers and optical switching based on MOEMS technology will improve future wavelength division multiplexing (WDM) systems. WDM vastly increases the speed of military communications and sensor data processing. From my designs, structures are prepared by molecular beam epitaxy. I design a mask set for studies of crystal plane selectivity. I perform a series of experiments on the selective …


Design And Fabrication Of Micro-Electro-Mechanical Structures For Tunable Micro-Optical Devices, Michael C. Harvey Mar 2002

Design And Fabrication Of Micro-Electro-Mechanical Structures For Tunable Micro-Optical Devices, Michael C. Harvey

Theses and Dissertations

Tunable micro-optical devices are expected to be vital for future military optical communication systems. In this research I seek to optimize the design of a microelectromechanical (MEM) structure integrated with a III-V semiconductor micro-optical device. The resonant frequency of an integrated optical device, consisting of a Fabry-Perot etalon or vertical cavity surface emitting laser (VCSEL), may be tuned by applying an actuation voltage to the MEM Flexure, thereby altering the device's optical cavity length. From my analysis I demonstrate tunable devices compatible with conventional silicon 5V integrated circuit technology. My design for a Fabry-Perot etalon has a theoretical tuning range …


Control And Characterization Of Line-Addressable Micromirror Arrays, Harris J. Hall Mar 2001

Control And Characterization Of Line-Addressable Micromirror Arrays, Harris J. Hall

Theses and Dissertations

This research involved the design and implementation of a complete line-addressable control system for a 32x32 electrostatic piston-actuated micromirror array device. Line addressing reduces the number of control lines from N2 to 2N making it possible to design larger arrays and arrays with smaller element sizes. The system utilizes the electromechanical bi-stability of individual elements to bold arbitrary bi-stable phase patterns. The control system applies pulse width modulated (PWM) signals to the rows and columns of the micromirror array. Three modes of operation were conceived and built into the system. The first was the traditional signal scheme which requires …


The Air Force Institute Of Technology (Afit) Micro Electro-Mechanical Systems (Mems) Interferometric Gyroscope (Mig), Jeremy P. Stringer Mar 2000

The Air Force Institute Of Technology (Afit) Micro Electro-Mechanical Systems (Mems) Interferometric Gyroscope (Mig), Jeremy P. Stringer

Theses and Dissertations

With the invention of Micro Electro-Mechanical Systems (MEMS) it has become possible to fabricate micro-inertial sensors. These new sensors have application in creating autonomous guided weapons systems. New technologies like Micro Unmanned Aerial Vehicles (UAVs), which cannot use conventional inertial sensors, rely on technologies like micro-inertial sensors to operate. Also, such sensors have the capability to reduce both power and space consumption on conventional aircraft. This technology is not yet mature, and current micro-inertial sensors do not have the accuracy required for highly precise navigation. To try to increase the accuracy of micro-inertial sensors, researchers are turning toward micro-optical gyroscopes. …


Electro-Mechanical Fatigue Behavior Of A Quasi-Isotropic Laminate With An Embedded Piezoelectric Actuator, Tse Lin Hsu Sep 1998

Electro-Mechanical Fatigue Behavior Of A Quasi-Isotropic Laminate With An Embedded Piezoelectric Actuator, Tse Lin Hsu

Theses and Dissertations

This study primarily investigated the electro-mechanical fatigue behavior of the embedded piezoelectric actuators in graphite/epoxy laminate with a lay-up of 0 | ± 45 | 90s. A secondary focus was the investigation of the mechanical fatigue effects of the 0 | 0 | ± 45 | 0 | 0 | 90s laminate with embedded PZT under tensile loading. All the fatigue tests were conducted with a triangular loading waveform which had a frequency of 10 Hz and with R=0. 1. In the electro-mechanical testing, the embedded actuator was excited by a -10 V to -100 V or a 10 V …


Microelectromechanical Scanner Using A Vertical Cavity Surface Emitting Laser, Joseph G. Bouchard Jr. Dec 1997

Microelectromechanical Scanner Using A Vertical Cavity Surface Emitting Laser, Joseph G. Bouchard Jr.

Theses and Dissertations

Optical scanners play a prominent role in the commercial and military industries. The scanner's size, cost and reliability are critical characteristics. In this research a microoptical scanning system was fabricated by incorporating a vertical cavity surface emitting laser (VCSEL) onto a surface machined microelectromechanical die. The micro optics for laser beam steering includes a 135 deg mirror, a Fresnel lens, a lateral scanning rotating mirror, and a vertical scanning fan mirror. The VCSEL was attached to the die by solder and electrical connection was provided by wire bonding. Based on far field measurements the scanner had a lateral scan angle …


Microelectromechanical Optical Beam Steering Systems, David M. Burns Dec 1997

Microelectromechanical Optical Beam Steering Systems, David M. Burns

Theses and Dissertations

The development of microelectromechanical systems (MEMS) has matured to the point where the fabrication of micron sized devices is feasible. State of the art MEMS construction processes now support the fabrication of novel optical devices that could not previously be built. This dissertation reports on the development of innovative micro optical devices such as Variable Blaze Gratings (VBGs) using state of the art MEMS construction processes. The principle application of the micro optical devices described in this dissertation is steering optical beams; however other applications such as spectral analysis are identified. Specific optical beam steering systems developed and characterized in …


Micro-Electromechanical Switches For Micro-Satellite Power Transfer, Glen A. Kading Dec 1997

Micro-Electromechanical Switches For Micro-Satellite Power Transfer, Glen A. Kading

Theses and Dissertations

In the past few years, microelectromechanical systems (MEMS) have emerged as a promising new technology with tremendous application potential. One of the possible implementations of MEMS technology is in the development of micro-satellites. It should be possible to mass-produce micro-satellites at a fraction of the cost of one conventional satellite. In order for satellites to be robust, a method of transferring power to systems must be addressed. As micro-satellites are made with conventional integrated circuit technologies at a very small scale, a means of transferring power on a similar scale will be investigated. This research addresses the issue of the …


Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts Dec 1996

Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts

Theses and Dissertations

MEMS (Micro-Electro-Mechanical Systems) micromirror devices can be used to control the phase of a propagating light wavefront, and in particular to correct aberrations that may be present in the wavefront, due to either atmospheric turbulence or any other type of fixed or time and space varying aberrations. In order to shorten the design cycle of MEMS micromirror devices, computer software is developed to create, from MEMS micromirror device design data, a numerical model of the MEMS device. The model is then used to compute the far field diffraction pattern of a wavefront reflected from the device, and to predict the …


Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick Dec 1996

Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick

Theses and Dissertations

This research conducted the first demonstrated use of a micro-electro-mechanical structure (MEMS) mirror array to correct a static optical aberration. A well-developed technique in adaptive optics imaging systems uses a deformable mirror to reflect the incident wave front to the imaging stage of the system. By matching the surface of the deformable mirror to the shape of the wave front phase distortion, the reflected wave front will be less aberrated before it is imaged. Typical adaptive optics systems use piezo-electric actuated deformable mirrors. This research used an electrostatically actuated, segmented mirror array, constructed by standard MEMS fabrication techniques, to investigate …


Microelectromechanical Isolation Of Acoustic Wave Resonators, James R. Reid Jr. Dec 1996

Microelectromechanical Isolation Of Acoustic Wave Resonators, James R. Reid Jr.

Theses and Dissertations

Microelectromechainical systems (MEMS) is a rapidly expanding field of research into the design and fabrication of actuated mechanical systems on the order of a few micrometers to a few millimeters. MEMS potentially offers new methods to solve a variety of engineering problems. A large variety of MEMS systems including flip-up platforms, scanning micromirrors, and rotating micromirrors are developed to demonstrate the types of MEMS that can be fabricated. The potential of MEMS for reducing the vibration sensitivity of surface acoustic wave and surface transverse wave resonators is then evaluated. A micromachined vibration isolation system is designed and modeled. A fabrication …


Artificial Cochlea Design Using Micro-Electro-Mechanical Systems, George C. Dalton Ii Dec 1996

Artificial Cochlea Design Using Micro-Electro-Mechanical Systems, George C. Dalton Ii

Theses and Dissertations

The use of Micro-Electro-Mechanical Systems (MEMS) in the design of an artificial cochlea is investigated in depth. Interdigitated finger (comb), cantilever, bridge, and mirror resonators are presented as possible devices used to implement the artificial cochlea. These resonators are demonstrated to be extremely high Q devices, capable of being tuned with a simple DC bias. This suggests a possible change to existing cochlea models that claim highly complex AC feedback as being responsible for changes in the damping of the basilar membrane. The new cochlea model presented here, using MEMS to approximate the tuning of the basilar membrane, may be …


Structures And Techniques For Implementing And Packaging Complex, Large Scale Microelectromechanical Systems Using Foundry Fabrication Processes, John H. Comtois Jun 1996

Structures And Techniques For Implementing And Packaging Complex, Large Scale Microelectromechanical Systems Using Foundry Fabrication Processes, John H. Comtois

Theses and Dissertations

Microelectromechanical Systems, or 'MEMS' is a broad new field of research into devices that range in size from a few microns to a few millimeters. Much of the technology supporting MEMS research is borrowed from the microelectronics industry; so MEMS holds out the promise of batch fabrication of microminiaturized machines that can be easily integrated with electronics. This dissertation research investigated structures and methods for implementing and packaging complex, large scale microelectromechanical devices and systems using commercially available foundry fabrication processes. It specifies methods for creating and packaging large, complex MEM systems, allowing the exploration of new MEMS architectures at …