Engineering Commons^™

Femtosecond Laser Micromachining Of Low-Temperature Co-Fired Ceramic And Glass Fiber Reinforced Polymer Printed Circuit Boards Materials, Raif Farkouh

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Low-temperature co-fired ceramic (LTCC), and glass fiber reinforced polymer (GFRP) printed circuit boards (PCBs) are two materials used for the packaging of electronics. The excellent mechanical and electrical properties of LTCC, combined with the ability to embed passive components offer superior radio frequency (RF) performance and device miniaturization for high-frequency applications. Due to its unique properties, LTCC provides superior performance in applications as diverse as military radar, imaging systems, advanced automotive sensing, telecommunications, and satellites. The use of LTCC in these applications has created a demand for the micromachining of holes, channels, and cavities with specific geometries and structures. Likewise, …

Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

In this thesis, complex anisotropic materials are investigated and characterized by generalized ellipsometry. In recent years, anisotropic materials have gained considerable interest for novel applications in electronic and optoelectronic devices, mostly due to unique properties that originate from reduced crystal symmetry. Examples include white solid-state lighting devices which have become ubiquitous just recently, and the emergence of high-power, high-voltage electronic transistors and switches in all-electric vehicles. The incorporation of single crystalline material with low crystal symmetry into novel device structures requires reconsideration of existing optical characterization approaches. Here, the generalized ellipsometry concept is extended to include applications for materials with …

Synthesis Of Graphene And Graphene-Based Composite Membrane, Yuanjun Fan

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Vibration membrane equipped for earphone requires high performance in both mechanical properties and electronic properties. With extraordinary properties on both, graphene and graphene-based composite materials appear as a promising candidate for this application. Chemical vapor deposition (CVD) is believed to be the most convenient way to synthesize a large area (on scale of square centimeters) as well as a homogeneous thickness for the membrane. The thesis focuses on applying control variable experiment method to analyze different effects on mechanical property of the two CVD setting parameters: cooling rate, and hydrocarbon precursor. For isolating the specimens efficiently, a modified electrochemical method …

Method For Single Crystal Growth Of Photovoltaic Perovskite Material And Devices, Jinsong Huang, Qingfeng Dong

Department of Mechanical and Materials Engineering: Faculty Publications

Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container , also including at least one small perovskite single crystal , and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows , in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate . For example , a top portion of the substrate external to the solution may be cooled .

Oct-Based Three Dimensional Modeling Of Stent Deployment, Pengfei Dong, David Prabhu, David L. Wilson, Hiram G. Bezerra, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Stent deployment has been widely used to treat narrowed coronary artery. Its acute outcome in terms of stent under expansion and malapposition depends on the extent and shape of calcifications. However, no clear understanding as to how to quantify or categorize the impact of calcification. We have conducted ex vivo stenting characterized by the optical coherence tomography (OCT). The goal of this work is to capture the ex vivo stent deployment and quantify the effect of calcium morphology on the stenting. A three dimensional model of calcified plaque was reconstructed from ex vivo OCT images. The crimping, balloon expansion and …

Floating-Gate Transistor Photodetector, Jinsong Huang, Yongbo Yuan

Department of Mechanical and Materials Engineering: Faculty Publications

A field effect transistor photodetector that can operate in room temperature includes a source electrode , a drain electrode , a channel to allow an electric current to flow between the drain and source electrodes , and a gate electrode to receive a bias voltage for controlling the current in the channel . The photodetector includes a light - absorbing mate rial that absorbs light and traps electric charges . The light absorbing material is configured to generate one or more charges upon absorbing light having a wavelength within a specified range and to hold the one or more charges …

Software For Extracting Deformation Gradient And Stress From Md Simulations: Simulations Using The Charmm Force Field, Mehrdad Negahban, Lili Zhang, Zesheng Zhang, John Jasa, Antoine Jérusalem

Department of Mechanical and Materials Engineering: Faculty Publications

Software was developed, and is provided under a general use license, to calculate continuum level deformation gradient and stress for any group of atoms in an MD simulation that uses the Charmm force fields. This software can also calculate the interaction stress applied by one group of atoms on any other group. To obtain deformation gradient and stress, the user needs to provide the selected group(s) of atoms in an atom group identification file, and provide the associated LAMMPS format files and force field parameter file. An example is included to demonstrate the use of the software.

Energy Absorbing Guardrail System, John R. Rohde, John D. Reid, King K. Mak, Dean L. Sicking

Department of Mechanical and Materials Engineering: Faculty Publications

A highway crash attenuation system having W - beam rail elements attached to a plurality of vertical posts . An impact terminal with a feeder chute guides one or more of the W - beam rail elements through the impact terminal . The feeder chute has an impact shield extending along a traffic facing side of the chute from an upstream - most end to a downstream - most end of the chute closing the traffic - facing side of the chute . The system also has an anchor cable release mechanism for releasing the cable downstream of the first …

Shape-Adaptive Mechanism For Robotic Grasping, Carl A. Nelson

Department of Mechanical and Materials Engineering: Faculty Publications

A grapser can include a first pantograph cell and a second pantograph cell coupled with the first pantogrpah cell. The first and second pantograph cells can be coupled together at a first pivot and a second pivot. The grasper can also include a finger extendable in a direction extending between the first pivot and the second pivot. The grasper can include a support base, where one or more links of the first pantograph cell can be slidably coupled with the support base for extending the grasper. In some embodiment, the grasper can be configured to extend along a curved path. …

Meniscus-Assisted Solution Printing Of Largegrained Perovskite Films For High-Efficiency Solar Cells, Ming He, Bo Li, Xun Cui, Beibei Jiang, Yanjie He, Yihuang Chen, Daniel O'Neil, Paul Szymanski, Mostafa A. El-Sayed, Jinsong Huang, Zhiqun Lin

Department of Mechanical and Materials Engineering: Faculty Publications

Control over morphology and crystallinity of metal halide perovskite films is of key importance to enable high-performance optoelectronics. However, this remains particularly challenging for solution-printed devices due to the complex crystallization kinetics of semiconductor materials within dynamic flow of inks. Here we report a simple yet effective meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. Intriguingly, the outward convective flow triggered by fast solvent evaporation at the edge of the meniscus ink imparts the transport of perovskite solutes, thus facilitating the growth of micrometre-scale perovskite grains. The growth kinetics of perovskite …

Elastic Properties Of Superconductors And Materials With Weakly Correlated Spins, Christian Binek

Christian Binek Publications

It is shown that in the ergodic regime, the temperature dependence of Young’s modulus is solely determined by the magnetic properties of a material. For the large class of materials with paramagnetic or diamagnetic response, simple functional forms of the temperature derivative of Young’s modulus are derived and compared with experimental data and empirical results. Superconducting materials in the Meissner phase are ideal diamagnets. As such, they display remarkable elastic properties. Constant diamagnetic susceptibility gives rise to a temperature independent elastic modulus for ceramic and single crystalline superconductors alike. The thermodynamic approach established in this report, paves the way to …

Dissipative Elastic Metamaterial With A Lowfrequency Passband, Yongquan Liu, Jianlin Yi, Zheng Li, Xianyue Su, Wenlong Li, Mehrdad Negahban

Department of Mechanical and Materials Engineering: Faculty Publications

We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its …

Multiple Scattering Theory For Heterogeneous Elastic Continua With Strong Property Fluctuation: Theoretical Fundamentals And Applications, Huijing He

Department of Mechanical and Materials Engineering: Faculty Publications

Scattering of elastic waves in heterogeneous media has become one of the most important problems in the field of wave propagation due to its broad applications in seismology, natural resource exploration, ultrasonic nondestructive evaluation and biomedical ultrasound. Nevertheless, it is one of the most challenging problems because of the complicated medium inhomogeneity and the complexity of the elastodynamic equations. A widely accepted model for the propagation and scattering of elastic waves, which properly incorporates the multiple scattering phenomenon and the statistical information of the inhomogeneities is still missing. In this work, the author developed a multiple scattering model for heterogeneous …

A Strategy To Optimize Recovery In Orthopedic Sports Injuries, Michael P. Sealy, Ziye Liu, Chao Li, Yuebin Guo, Ben White, Mark Barkey, Brian Jordon J, Luke N. Brewer, Dale Feldman

Department of Mechanical and Materials Engineering: Faculty Publications

An important goal for treatment of sports injuries is to have as short a recovery time as possible. The critical problem with current orthopedic implants is that they are designed to be permanent and have a high complication rate (15%) that often requires removal and replacement with a second surgery; and subsequently a second rehabilitation cycle. This study was designed to test the feasibility of having a device that could provide the needed mechanical properties, while promoting healing, for a specified amount of time and then degrade away, to shorten the recovery time. The specific strategy was to create a …

Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

No abstract provided.

Primary Blast Waves Induced Brain Dynamics Influenced By Head Orientations, Yi Hua, Yugang Wang, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

There is controversy regarding the directional dependence of head responses subjected to blast loading. The goal of this work is to characterize the role of head orientation in the mechanics of blast wave-head interactions as well as the load transmitting to the brain. A three-dimensional human head model with anatomical details was reconstructed from computed tomography images. Three different head orientations with respect to the oncoming blast wave, i.e., front-on with head facing blast, back-on with head facing away from blast, and side-on with right side exposed to blast, were considered. The reflected pressure at the blast wave-head interface positively …

Formation Of Mound-Like Multiscale Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Ryan Bell, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Surface Functionalization Technique • Femtosecond Laser Surface Processing (FLSP) • Utilize high power, femtosecond (10-15 s) laser pulses • Produce self-organized, multiscale surface micro/nanostructures • Diverse range of applicable substrates: semiconductors, metals, polymers, & composites

Why? • What are the different types of FLSP structures on Ti? • Physical evidence needed for FLSP formation models • Optimize FLSP of Ti for biomedical & other applications

How? • Obtain evidence of mound growth processes by examining underlying microstructure • Utilize dual beam Scanning Electron Microscope-Focused Ion Beam instrument to cross section surface structures & fabricate transmission electron microscopy samples

Dirichlet Process Gaussian Mixture Models For Real-Time Monitoring And Their Application To Chemical Mechanical Planarization, Jia (Peter) Liu, Omer F. Beyca, Prahalad K. Rao, Zhenyu (James) Kong, Satish T. S. Bukkapatnam

Department of Mechanical and Materials Engineering: Faculty Publications

The goal of this work is to use sensor data for online detection and identification of process anomalies (faults). In pursuit of this goal, we propose Dirichlet process Gaussian mixture (DPGM) models. The proposed DPGM models have two novel outcomes: 1) DP-based statistical process control (SPC) chart for anomaly detection and 2) unsupervised recurrent hierarchical DP clustering model for identification of specific process anomalies. The presented DPGM models are validated using numerical simulation studies as well as wireless vibration signals acquired from an experimental semiconductor chemical mechanical planarization (CMP) test bed. Through these numerically simulated and experimental sensor data, we …

Vorticella: A Protozoan For Bio-Inspired Engineering, Sangjin Ryu, Rachel E. Pepper, Moeto Nagai, Danielle C. France

Department of Mechanical and Materials Engineering: Faculty Publications

In this review, we introduce Vorticella as a model biological micromachine for microscale engineering systems. Vorticella has two motile organelles: the oral cilia of the zooid and the contractile spasmoneme in the stalk. The oral cilia beat periodically, generating a water flow that translates food particles toward the animal at speeds in the order of 0.1–1 mm/s. The ciliary flow of Vorticella has been characterized by experimental measurement and theoretical modeling, and tested for flow control and mixing in microfluidic systems. The spasmoneme contracts in a few milliseconds, coiling the stalk and moving the zooid at 15–90 mm/s. Because the …

Benchmark Burnishing With Almen Strip For Surface Integrity, Z. Y. Liu, C. H. Fu, M. P. Sealy, Y. Zhao, Y. B. Guo

Department of Mechanical and Materials Engineering: Faculty Publications

Burnishing is a surface treatment process widely used in aerospace, navy and other industries to improve fatigue and corrosion resistance by introducing a compressive residual stress layer. The measurement of residual stress by XRD is expensive, time consuming, and tedious. This work presented a quick method to determine the residual stress by using Almen strips. Inspired by the application of Almen strips in shot peening, deflections of burnished Almen strips under different burnishing conditions were measured. It was found that the deflection of Almen strip reflects the magnitude and penetration depth into subsurface of induced stress. Higher burnishing force, smaller …

Methods , Systems , And Devices Relating To Surgical End Effectors, Shane M. Farritor, Tom Fredrick, Joe Bartels

Department of Mechanical and Materials Engineering: Faculty Publications

The embodiments disclosed herein relate to various medical device components, including components that can be incorporated into robotic and/or in vivo medical devices, and more specifically including end effectors that can be incorporated into such devices. Certain end effector embodiments include various vessel cautery devices that have rotational movement as well as cautery and cutting functions while maintaining a relatively compact structure. Other end effector embodiments include various end effector devices that have more than one end effector.

Suspended Graphene-Based Gas Sensor With 1-Mw Energy Consumption, Jong-Hyun Kim, Qin Zhou, Jiyoung Chang

Department of Mechanical and Materials Engineering: Faculty Publications

This paper presents NH₃ sensing with ultra-low energy consumption for fast recovery and a graphene sheet based on a suspended microheater. Sensitivity and repeatability are important characteristics of functional gas sensors embedded in mobile devices. Moreover, low energy consumption is an essential requirement in flexible and stretchable mobile electronics due to their small dimension and fluctuating resistivity during mechanical behavior. In this paper, we introduce a graphene-based ultra-low power gas detection device with integration of a suspended silicon heater. Dramatic power reduction is enabled by a duty cycle while not sacrificing sensitivity. The new oscillation method of heating improves …

Ferroelectricity And The Phase Transition In Large Area Evaporated Vinylidene Fluoride Oligomer Thin Films, Keith Foreman, Shashi Poddar, Stephen Ducharme, Shireen Adenwalla

Shireen Adenwalla Papers

Organic ferroelectric materials, including the well-known poly(vinylidene fluoride) and its copolymers, have been extensively studied and used for a variety of applications. In contrast, the VDF oligomer has not been thoroughly investigated and is not widely used, if used at all. One key advantage the oligomer has over the polymer is that it can be thermally evaporated in vacuum, allowing for the growth of complex heterostructures while maintaining interfacial cleanliness. Here, we report on the ferroelectric properties of high-quality VDF oligomer thin films over relatively large areas on the order of mm². The operating temperature is identified via …

Quantification Of Re-Absorption And Re-Emission Processes To Determine Photon Recycling Efficiency In Perovskite Single Crystals, Yanjun Fang, Haotong Wei, Qingfeng Dong, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Photon recycling, that is, iterative self-absorption and re-emission by the photoactive layer itself, has been speculated to contribute to the high open-circuit voltage in several types of high efficiency solar cells. For organic–inorganic halide perovskites that have yielded highly efficient photovoltaic devices, however, it remains unclear whether the photon recycling effect is significant enough to improve solar cell efficiency. Here we quantitatively evaluate the re-absorption and re-emission processes to determine photon recycling efficiency in hybrid perovskite with its single crystals by measuring the ratio of the re-emitted photons to the initially excited photons, which is realized by modulating their polarization …

High Temperature Near-Field Nanothermomechanical Rectification, Mahmoud Elzouka, Sidy Ndao

Department of Mechanical and Materials Engineering: Faculty Publications

Limited performance and reliability of electronic devices at extreme temperatures, intensive electromagnetic fields, and radiation found in space exploration missions (i.e., Venus & Jupiter planetary exploration, and heliophysics missions) and earth-based applications requires the development of alternative computing technologies. In the pursuit of alternative technologies, research efforts have looked into developing thermal memory and logic devices that use heat instead of electricity to perform computations. However, most of the proposed technologies operate at room or cryogenic temperatures, due to their dependence on material’s temperature-dependent properties. Here in this research, we show experimentally—for the first time—the use of near-field thermal radiation …

Methods, Systems, And Devices For Surgical Visualization And Device Manipulation, Shane M. Farritor, Mark Rentschler, Amy Lehman, Nathan A. Wood, Adam Bock, Reed Prior

Department of Mechanical and Materials Engineering: Faculty Publications

A surgical device includes a console having a visual display and a manipulator arm, a robotic device having a camera and a connection component. The robotic device is configured to be positioned completely within a body cavity. The camera is configured to transmit visual images to the visual display. The connection component operably couples the console and the robotic device. The manipulator arm is positioned relative to the visual display so as to appear to be penetrating the visual display.

Low-Drag Events In Transitional Wall-Bounded Turbulence, Richard D. Whalley, Jae Sung Park, Anubhav Kushwaha, David J.C. Dennis, Michael D. Graham, Robert J. Poole

Department of Mechanical and Materials Engineering: Faculty Publications

Intermittency of low-drag pointwise wall shear stress measurements within Newtonian turbulent channel flow at transitional Reynolds numbers (friction Reynolds numbers 70 – 130) is characterized using experiments and simulations. Conditional mean velocity profiles during low-drag events closely approach that of a recently discovered nonlinear traveling wave solution; both profiles are near the so-called maximum drag reduction profile, a general feature of turbulent flow of liquids containing polymer additives (despite the fact that all results presented are for Newtonian fluids only). Similarities between temporal intermittency in small domains and spatiotemporal intermittency in large domains is thereby found.

Flowtaxis Of Osteoblast Migration Under Fluid Shear And The Effect Of Rhoa Kinase Silencing, Brandon D. Riehl, Jeong Soon Lee, Ligyeom Ha, Il Keun Kwon, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

Despite the important role of mechanical signals in bone remodeling, relatively little is known about how fluid shear affects osteoblastic cell migration behavior. Here we demonstrated that MC3T3-E1 osteoblast migration could be activated by physiologically-relevant levels of fluid shear in a shear stress-dependent manner. Interestingly, shear-sensitive osteoblast migration behavior was prominent only during the initial period after the onset of the steady flow (for about 30 min), exhibiting shear stress-dependent migration speed, displacement, arrest coefficient, and motility coefficient. For example, cell speed at 1 min was 0.28, 0.47, 0.51, and 0.84 μm min^-1 for static, 2, 15, and 25 …

Atomically Informed Nonlocal Semidiscrete Variational Peierls-Nabarro Model For Planar Core Dislocations, Guisen Liu, Xi Cheng, Jian Wang, Kaiguo Chen, Yao Shen

Department of Mechanical and Materials Engineering: Faculty Publications

Prediction of Peierls stress associated with dislocation glide is of fundamental concern in understanding and designing the plasticity and mechanical properties of crystalline materials. Here, we develop a nonlocal semi-discrete variational Peierls-Nabarro (SVPN) model by incorporating the nonlocal atomic interactions into the semi-discrete variational Peierls framework. The nonlocal kernel is simplified by limiting the nonlocal atomic interaction in the nearest neighbor region, and the nonlocal coefficient is directly computed from the dislocation core structure. Our model is capable of accurately predicting the displacement profile, and the Peierls stress, of planar-extended core dislocations in face-centered cubic structures. Our model could be …

Fluid-Structure Interaction In Abdominal Aortic Aneurysm: Effect Of Modeling Techniques, Shengmao Lin, Xinwei Han, Yonghua Bi, Siyeong Ju, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

In this work, the impact of modeling techniques on predicting the mechanical behaviors of abdominal aortic aneurysm (AAA) is systematically investigated. The fluid-structure interaction (FSI) model for simultaneously capturing the transient interaction between blood flow dynamics and wall mechanics was compared with its simplified techniques, that is, computational fluid dynamics (CFD) or computational solid stress (CSS) model. Results demonstrated that CFD exhibited relatively smaller vortexes and tends to overestimate the fluid wall shear stress, compared to FSI. On the contrary, the minimal differences in wall stresses and deformation were observed between FSI and CSS models. Furthermore, it was found that …