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Air Force Institute of Technology

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Full-Text Articles in Electro-Mechanical Systems

Ion Irradiation Of Microelectromechanical Resonators, Hengky Chandrahalim, David D. Lynes Jun 2026

Ion Irradiation Of Microelectromechanical Resonators, Hengky Chandrahalim, David D. Lynes

AFIT Patents

A method of enhancing an electromechanical coupling coefficient of a microelectromechanical (“MEMS”) device. The method includes applying, to a fully fabricated MEMS device, heavy particle ion radiation to the MEMS device at a fluence of at least 1×1014 cm.−2. According to other embodiments of the present invention are directed to a bandpass filter comprising a plurality of MEMS devices fabricated in accordance with the methods provided. The MEMS of the plurality are electronically or mechanically coupled.


Fused-Silica Microelectromechanical Systems For Relative Gravimetry, Ethan Doerstling Jun 2025

Fused-Silica Microelectromechanical Systems For Relative Gravimetry, Ethan Doerstling

Theses and Dissertations

Gravimeters are devices that measure gravitational acceleration which can be used by the United States Air Force (USAF) in the areas of navigation and remote sensing. Fused-silica microelectromechanical systems (MEMS) devices offer capabilities to make inexpensive relative gravimeters with higher thermal stability than common silicon devices while maintaining good gravitational sensitivity. The fused-silica devices in this research were designed, simulated, fabricated, and tested to observe their performance as gravimeters. The devices exhibit properties of highly sensitive accelerometers but the current designs do not qualify as gravimeters. This study provides information to improve the sensitivity and stability of these fused-silica MEMS …


Impact Of Silicon Ion Irradiation On Aluminum Nitride-Transduced Microelectromechanical Resonators, David D. Lynes, Joshua Young, Eric Lang, Hengky Chandrahalim Nov 2023

Impact Of Silicon Ion Irradiation On Aluminum Nitride-Transduced Microelectromechanical Resonators, David D. Lynes, Joshua Young, Eric Lang, Hengky Chandrahalim

Faculty Publications

Microelectromechanical systems (MEMS) resonators use is widespread, from electronic filters and oscillators to physical sensors such as accelerometers and gyroscopes. These devices' ubiquity, small size, and low power consumption make them ideal for use in systems such as CubeSats, micro aerial vehicles, autonomous underwater vehicles, and micro-robots operating in radiation environments. Radiation's interaction with materials manifests as atomic displacement and ionization, resulting in mechanical and electronic property changes, photocurrents, and charge buildup. This study examines silicon (Si) ion irradiation's interaction with piezoelectrically transduced MEMS resonators. Furthermore, the effect of adding a dielectric silicon oxide (SiO2) thin film is …


Optical Fiber Tip Micro Anemometer, Jeremiah C. Williams, Hengky Chandrahalim Apr 2023

Optical Fiber Tip Micro Anemometer, Jeremiah C. Williams, Hengky Chandrahalim

AFIT Patents

A passive microscopic flow sensor includes a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fiber. The three-dimensional microscopic optical structure includes a post attached off-center to and extending longitudinally from the cleaved tip of the optical fiber. A rotor of the three-dimensional microscopic optical structure is received for rotation on the post. The rotor has more than one blade. Each blade has a reflective undersurface that reflects a light signal back through the optical fiber when center aligned with the optical fiber, the blades of the rotor shaped to rotate at a rate related to …


Modeling The Effects Of Radiation On Microelectromechanical Resonators, David D. Lynes Mar 2023

Modeling The Effects Of Radiation On Microelectromechanical Resonators, David D. Lynes

Theses and Dissertations

As the use of MEMS becomes more prolific in air, space, defense, and power applications, they will be exposed to more extreme radiation environments. This dissertation explores the effects of ionizing and nonionizing radiation on MEMS. AlN-on-Si based piezoelectric bulk acoustic wave resonators were irradiated by gamma-rays and silicon ions while measuring S-parameters in situ. Changes to the resonator and equivalent circuit parameters are extracted. The resonators demonstrated resilience against the effects of radiation-induced charge trapping. However, radiation-induced atomic displacements caused shifts to resonant frequency. From these data, an atomistic model is derived to describe the relationship between radiation type …


Simultaneous Actuation And Sensing Of Electrostatic Mems, Jacob E. Song Mar 2022

Simultaneous Actuation And Sensing Of Electrostatic Mems, Jacob E. Song

Theses and Dissertations

Micro-Electro-Mechanical Systems (MEMS) are devices that play important roles of sensing and actuation in many different industries including automation, electronics, medical, communications, and defense. In order to make full use of these devices, it is important to understand the peripherals that enable these devices. Simultaneous actuation and control of MEMS devices is an important area of research as it enables feedback control of these device and allows devices to maintain performance as devices depreciate over their lifetime. The aim of this thesis is to perform a design space analysis on an electrostatic MEMS simultaneous actuation and sensing circuit that is …


Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith Dec 2021

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor an optical fiber a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fighter that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.


Feasibility Study Of Radio Frequency Microelectromechanical Filters For Space Operation, Karanvir Singh Jun 2021

Feasibility Study Of Radio Frequency Microelectromechanical Filters For Space Operation, Karanvir Singh

Theses and Dissertations

Piezoelectric contour mode resonator technology has the unique advantage of combining low motional resistance with the ability to define multiple frequencies on the same substrate. Contour mode resonators can be mechanically coupled together to form robust band-pass filters for the next generation of GPS satellites with extreme size reduction compared to electrically coupled filters. Piezoelectric zinc oxide (ZnO) contour mode resonators have the potential for monolithic integration with current ZnO transistor further reducing size, power consumption, and cost of filter modules. Barium strontium titanate (BST) contour mode resonators have incredible frequency tunability due to the fundamental nature of the thin …


Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith Mar 2021

Temperature-Immune Self-Referencing Fabry–Pérot Cavity Sensors, Hengky Chandrahalim, Jonathan W. Smith

AFIT Patents

A passive microscopic Fabry-Pérot Interferometer (FPI) sensor an optical fiber a three-dimensional microscopic optical structure formed on a cleaved tip of an optical fighter that reflects a light signal back through the optical fiber. The reflected light is altered by refractive index changes in the three-dimensional structure that is subject to at least one of: (i) thermal radiation; and (ii) volatile organic compounds.


Robust Scandium Aluminum Nitride Mems Resonators For L Band Operation In Orbital Environments, Israel W. Dunk Mar 2021

Robust Scandium Aluminum Nitride Mems Resonators For L Band Operation In Orbital Environments, Israel W. Dunk

Theses and Dissertations

This thesis investigates AlN alloyed with scandium in a variety of resonator architectures including WEM, overtone WEM, LEM, and SAW that have the potential to achieve high levels of electrical performance and environmental robustness. SAW resonators operating near 370 MHz are fabricated on polycrystalline Sc.37Al.63N, and AlN with the resulting devices compared and conclusions drawn as to the merits of each material. The design and fabrication of SAW devices is discussed in detail, with the operating characteristics of these resonators then tested both electrically and mechanically. Mechanical characterisation includes analysis of vibration and shock effects on …


Characterization Of Reactive Ion Etch Chemistries Using Direct Write Lithography, Dylan T. Martin-Abood Mar 2020

Characterization Of Reactive Ion Etch Chemistries Using Direct Write Lithography, Dylan T. Martin-Abood

Theses and Dissertations

The DoD requires a variety of COTS and number of custom microelectronics to provide important functionality to critical military systems. Photolithography and DRIE are two techniques commonly used in the development of deep anisotropic features for the fabrication and modification of microelectronics and MEMS. However, standard photolithography techniques are ineffective for unique substrate geometries and DRIE processes require a chemical passivation step only applicable to Si substrates. This work confirmed the capability of RIE using DWL to perform deep, highly selective, anisotropic etching on elevated, non-circular substrates.


Thermal Management Using Microelectromechanical Systems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. K. Walton, Laverne A. Starman Oct 2019

Thermal Management Using Microelectromechanical Systems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. K. Walton, Laverne A. Starman

AFIT Patents

A cooling structure for a heat source, where the cooling structure includes a beam having a first end and a second end and a length disposed therebetween. The beam is formed at least in part of a first material having a first thermal coefficient of expansion and a second material having a second thermal coefficient of expansion, where the first thermal coefficient of expansion is different from the second thermal coefficient of expansion. The first end of the beam is thermally connected to the heat source, such that heat generated by the heat source is conducted along the length of …


Event-Based Visual-Inertial Odometry On A Fixed-Wing Unmanned Aerial Vehicle, Kaleb J. Nelson Mar 2019

Event-Based Visual-Inertial Odometry On A Fixed-Wing Unmanned Aerial Vehicle, Kaleb J. Nelson

Theses and Dissertations

Event-based cameras are a new type of visual sensor that operate under a unique paradigm. These cameras provide asynchronous data on the log-level changes in light intensity for individual pixels, independent of other pixels' measurements. Through the hardware-level approach to change detection, these cameras can achieve microsecond fidelity, millisecond latency, ultra-wide dynamic range, and all with very low power requirements. The advantages provided by event-based cameras make them excellent candidates for visual odometry (VO) for unmanned aerial vehicle (UAV) navigation. This document presents the research and implementation of an event-based visual inertial odometry (EVIO) pipeline, which estimates a vehicle's 6-degrees-of-freedom …


Micro-Contacts With 3-D Surfaces Made With Grayscale Lithography, Paul L.J. Michaud Mar 2019

Micro-Contacts With 3-D Surfaces Made With Grayscale Lithography, Paul L.J. Michaud

Theses and Dissertations

MEMS switches show advantages over FET transistors and PIN diodes for switching applications due to low contact resistance, high linearity, low power use, better isolation and lower insertion loss. The switches have not replaced FETs or PIN diodes due to perceived limitations in their reliability and the need for stable contact resistance. In order to create switches acceptable for industry applications, research on micro-contact physics and failure mechanisms of micro-contacts is necessary to develop durable contact surfaces. The aim of this research was to design and fabricate micro-contacts with three-dimensional surfaces using grayscale lithography. The goal was to create devices …


A Mems Dual Vertical Electrometer And Electric Field-Mill, George C. Underwood Mar 2019

A Mems Dual Vertical Electrometer And Electric Field-Mill, George C. Underwood

Theses and Dissertations

Presented is the first iteration of a Microelectromechanical System (MEMS) dual vertical electrometer and electric field-mill (EFM). The device uses a resonating structure as a variable capacitor that converts the presence of a charge or field into an electric signal. Previous MEMS electrometers are lateral electrometers with laterally spaced electrodes that resonate tangentially with respect to each other. Vertical electrometers, as the name suggests, have vertically spaced electrodes that resonate transversely with respect to each other. The non-tangential movement reduces damping in the system. Both types demonstrate comparable performance, but the vertical electrometer does so at a fraction of the …


Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie Feb 2016

Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie

Faculty Publications

In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom …


Novel Applications Of A Thermally Tunable Bistable Buckling Silicon-On-Insulator (Soi) Microfabricated Membrane, Robert A. Lake Sep 2015

Novel Applications Of A Thermally Tunable Bistable Buckling Silicon-On-Insulator (Soi) Microfabricated Membrane, Robert A. Lake

Theses and Dissertations

Buckled membranes are commonly used microelectromechanical systems (MEMS) structures. Recent work has demonstrated that the deflection and stiffness of these membranes can be tuned through localized joule heating. These devices were implemented into the design and fabrication of two novel device applications, a tunable pressure sensor and a steerable micromirror. A differential pressure across the membrane causes de reflection, up or down, which can be measured and related to a specific pressure. By tuning the stiffness of the membrane, its pressure response is varied providing a wider range of application for the pressure sensor. A 2.0mm by 2.0mm square membrane …


Mems Cantilever Sensor For Thz Photoacoustic Chemical Sensing And Spectroscopy, Nathan E. Glauvitz Dec 2013

Mems Cantilever Sensor For Thz Photoacoustic Chemical Sensing And Spectroscopy, Nathan E. Glauvitz

Theses and Dissertations

Sensitive Microelectromechanical System (MEMS) cantilever designs were modeled, fabricated, and tested to measure the photoacoustic (PA) response of gasses to terahertz (THz) radiation. Surface and bulk micromachining technologies were employed to create the extremely sensitive devices that could detect very small changes in pressure. Fabricated devices were then tested in a custom made THz PA vacuum test chamber where the cantilever deflections caused by the photoacoustic effect were measured with a laser interferometer and iris beam clipped methods. The sensitive cantilever designs achieved a normalized noise equivalent absorption coefficient of 2.83x10-10 cm-1 W Hz-1/2 using a 25 …


Mems Fabrication Process Base On Su-8 Masking Layers, Scott A. Ostrow, Ronald A. Coutu Jr. Nov 2013

Mems Fabrication Process Base On Su-8 Masking Layers, Scott A. Ostrow, Ronald A. Coutu Jr.

AFIT Patents

A novel fabrication process uses a combination of negative and positive photoresists with positive tone photomasks, resulting in masking layers suitable for bulk micromachining high-aspect ratio microelectromechanical systems (MEMS) devices. This technique allows the use of positive photomasks with negative resists, opening the door to an ability to create complementary mechanical structures without the fabrication delays and costs associated with having to obtain a negative photomask. In addition, whereas an SU-8 mask would normally be left in place after processing, a technique utilizing a positive photoresist as a release layer has been developed so that the SU-8 masking material can …


Digitally Programmable Rf Mems Filters With Mechanically Coupled Resonators, Hengky Chandrahalim, Sunil Ashok Bhave Mar 2013

Digitally Programmable Rf Mems Filters With Mechanically Coupled Resonators, Hengky Chandrahalim, Sunil Ashok Bhave

AFIT Patents

A digitally-tunable RF MEMS filter includes a substrate and a plurality of mechanically coupled resonators, wherein a first and a last resonator of the plurality of mechanically coupled resonators are configured to be electrostatically transduced. One or more of the plurality of mechanically coupled resonators are configured to be biased relative to the substrate such that the one or more biased resonators may be brought substantially in contact with the substrate. In a method of digitally tuning an RF MEMS filter having a mechanically coupled resonator array, a DC bias voltage is applied to at least a first resonator and …


Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane Mar 2011

Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane

AFIT Patents

A MEMS switch fabrication process and apparatus inclusive of a bulbous rounded surface movable contact assembly that is integral with the switch movable element and achieving of long contact wear life with low contact electrical resistance. The disclosed process is compatible with semiconductor integrated circuit fabrication materials and procedures and includes an unusual photoresist reflow step in which the bulbous contact shape is quickly defined in three dimensions from more easily achieved integrated circuit mask and etching-defined precursor shapes. A plurality of differing photoresist materials are used in the process. A large part of the contact and contact spring formation …


Electromagnetic Modeling And Measurement Of Adaptive Metamaterial Structural Elements, Matthew E. Jussaume Mar 2011

Electromagnetic Modeling And Measurement Of Adaptive Metamaterial Structural Elements, Matthew E. Jussaume

Theses and Dissertations

This document addresses two major obstacles facing metamaterial development: uncertainty in the characterization of electromagnetic field behavior in metamaterial structures and the relatively small operational bandwidth of metamaterial structures. To address the first obstacle, a method of prediction aided measurement is developed and exploited to examine the field interactions within metamaterial devices. The fusion of simulation and measurement techniques enhances the understanding of the physical interactions of fields in the presence of metamaterials. To address the second obstacle, this document characterizes the effectiveness of an adaptive metamaterial design that incorporates a microelectromechanical systems (MEMS) variable capacitor. Applying voltages to the …


Increasing The Sensitivity Of Surface Acoustic Wave (Saw) Chemical Sensors And Other Chemical Sensing Investigations, Nina R. Smith Mar 2010

Increasing The Sensitivity Of Surface Acoustic Wave (Saw) Chemical Sensors And Other Chemical Sensing Investigations, Nina R. Smith

Theses and Dissertations

The work involves the fabrication and testing of three different surface acoustic wave (SAW) device designs, an investigation of nanowires sensitive to chemicals and preconcentrator prototypes to include with chemical sensors. The SAW chemical sensor designs include modifications to a basic SAW device to see if the sensitivity of the SAW device is increased. The modifications consist of etched trenches along the propagation field, coating the device with carbon nanotubes (CNTs) under the chemically sensitive layer and coating CNTs on top of the chemically sensitive layer. SAW devices are coated with Nafion®, a polymer sensitive to ethanol. The tests indicate …


Investigation Of Thermal Management And Metamaterials, Calvin T. Roman Mar 2010

Investigation Of Thermal Management And Metamaterials, Calvin T. Roman

Theses and Dissertations

Thermal metamaterials are materials composed of engineered, microscopic structures that exhibit unique thermal performance characteristics based primarily on their physical structures and patterning, rather than just their chemical composition or bulk material properties. The heat transfer performance attributes of a thermal metamaterial are such that similar performance cannot be obtained using conventional materials or compounds. Thermal metamaterials are an emerging technology, and are just now beginning to be acknowledged and developed by the microelectronics and material sciences community. This thesis effort analyzed the current state of thermal metamaterial research, examined the physics and theory of heat transfer and electrical conductivity …


Investigation Into Contact Resistance And Damage Of Metal Contacts Used In Rf-Mems Switches, Kevin W. Gilbert Dec 2009

Investigation Into Contact Resistance And Damage Of Metal Contacts Used In Rf-Mems Switches, Kevin W. Gilbert

Theses and Dissertations

This research examines the physical and electrical processes involved in lifecycle failure of Microelectromechanical (MEMS) Radio-Frequency (RF) cantilever beam ohmic contact switches. Failures of these switches generally occur at the contact, but complete details of performance of microcontacts are difficult to measure and have not been previously reported. This study investigated the mechanics of microcontact behavior by designing and constructing a novel experimental setup. Three representative contact materials of varying microstructure (Au, Au5%Ru, Au4%V2O5) were tested and parameters of contact during cycling were measured. The Au4%V2O5, a dispersion strengthened material developed at …


Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane Oct 2009

Shaped Mems Contact, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane

AFIT Patents

A MEMS switch fabrication process and apparatus inclusive of a bulbous rounded surface movable contact assembly that is integral with the switch movable element and achieving of long contact wear life with low contact electrical resistance. The disclosed process is compatible with semiconductor integrated circuit fabrication materials and procedures and includes an unusual photoresist reflow step in which the bulbous contact shape is quickly defined in three dimensions from more easily achieved integrated circuit mask and etching-defined precursor shapes. A plurality of differing photoresist materials are used in the process. A large part of the contact and contact spring formation …


Electrically Steerable Diffraction Gratings For Hyperspectral Imaging: A Microelectromechanical System Design And Fabrication, Saban Atinc Delican Mar 2008

Electrically Steerable Diffraction Gratings For Hyperspectral Imaging: A Microelectromechanical System Design And Fabrication, Saban Atinc Delican

Theses and Dissertations

The current research is focused on the design and fabrication of an electrically programmable diffraction grating using standard micro electro mechanical systems (MEMS) technology. The goal is to design a beam steering element required to build very small hyperspectral imaging (HSI) sensors. The diffraction grating will be used to perform beam-dispersion - a critical step in the imaging process. The proposed transmissive diffraction grating based approach will minimize the overall size and the number of components in the physical design of the hyperspectral imagers, thereby enabling us to exploit the traditional advantages of MEMS such as increased reliability, smaller size, …


Performance Comparison Of Pb(Zr0.52Ti0.48)O3-Only And Pb(Zr0.52Ti0.48)O3-On-Silicon Resonators, Hengky Chandrahalim, Sunil A. Bhave, Ronald G. Polcawich, Jeff Pulskamp, Dan Judy, Roger Kaul, Madan Dubey Jan 2008

Performance Comparison Of Pb(Zr0.52Ti0.48)O3-Only And Pb(Zr0.52Ti0.48)O3-On-Silicon Resonators, Hengky Chandrahalim, Sunil A. Bhave, Ronald G. Polcawich, Jeff Pulskamp, Dan Judy, Roger Kaul, Madan Dubey

Faculty Publications

This paper provides a quantitative comparison and explores the design space of lead zirconium titanate (PZT)–only and PZT-on-silicon length-extensional mode resonators for incorporation into radio frequency microelectromechanical system filters and oscillators. We experimentally measured the correlation of motional impedance (RX) and quality factor (Q) with the resonators’ silicon layer thickness (tSi). For identical lateral dimensions and PZT-layer thicknesses (tPZT), the PZT-on-silicon resonator has higher resonant frequency (fC), higher Q (5100 versus 140), lower RX (51 Ω versus 205 Ω), and better linearity [third-order input intercept …


Conceptual Mems Devices For A Redeployable Antenna, Virginia Miller Sep 2007

Conceptual Mems Devices For A Redeployable Antenna, Virginia Miller

Theses and Dissertations

Micro-Electro-Mechanical Systems (MEMS) are becoming an integral part of our lives through a wide range of applications, including MEMS accelerators for air bag deployment in vehicles, micromirrors in projection devices, and various sensors for chemical/biological applications. MEMS are a key aspect of ever-increasing significance in a myriad of commercial and military applications. Because of this importance, this thesis utilizes MEMS devices that can deploy and retract an antenna suitably sized for placement on an insect or microrobot for communication purposes. A target monopole antenna with a length of 1 mm was used as a test metric. From this requirement, several …


Radio Frequency Mems Switch Contact Metal Selection, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane, Kevin D. Leedy Jun 2007

Radio Frequency Mems Switch Contact Metal Selection, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane, Kevin D. Leedy

AFIT Patents

A method for selecting metal alloys as the electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This method includes a review of alloy experience, consideration of equilibrium binary alloy phase diagrams, obtaining thin film material properties and, based on a suitable model, predicting contact electrical resistance performance. After determination of a candidate alloy material, MEMS switches are conceptualized, fabricated and tested to validate the alloy selection methodology. Minimum average contact resistance values of 1.17 and 1.87 ohms are achieved for micro-switches with gold (Au) and gold-platinum (Au-(6.3 at %)Pt) alloy contacts. In addition, `hot-switched` life cycle test results …