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Selective Resistive Sintering: A Novel Additive Manufacturing Process, Austin Bryan Van Horn

Graduate Theses and Dissertations

Selective laser sintering (SLS) is one of the most popular 3D printing methods that uses a laser to pattern energy and selectively sinter powder particles to build 3D geometries. However, this printing method is plagued by slow printing speeds, high power consumption, difficulty to scale, and high overhead expense. In this research, a new 3D printing method is proposed to overcome these limitations of SLS. Instead of using a laser to pattern energy, this new method, termed selective resistive sintering (SRS), uses an array of microheaters to pattern heat for selectively sintering materials. Using microheaters offers significant power savings, significantly …

Mechanical Reliability Of Implantable Polyimide-Based Magnetic Microactuators For Biofouling Removal, Christian G. Figueroa-Espada, Qi Yang, Hyowon Lee

The Summer Undergraduate Research Fellowship (SURF) Symposium

Hydrocephalus is a neurological disorder that typically requires a long-term implantation of a shunt system to manage its symptoms. These shunt systems are notorious for their extremely high failure rate. More than 40% of all implanted shunt systems fail within the first year of implantation. On average, 85% of all hydrocephalus patients with shunt systems undergo at least two shunt-revision surgeries within 10 years of implantation. A large portion of this high failure rate can be attributed to biofouling-related obstructions and infections. Previously, we developed flexible polyimide-based magnetic microactuators to remove obstructions formed on hydrocephalus shunts. To test the long-term …

Analytical Modeling Of A Novel Microdisk Resonator For Liquid-Phase Sensing: An All-Shear Interaction Device (Asid), Mohamad Sadegh Sotoudegan

Dissertations (1934 -)

Extensive research on micro/nanomechanical resonators has been performed recently due to their potential to serve as ultra-sensitive devices in chemical/biosensing. These applications often necessitate liquid-phase sensing, introducing significant fluid-induced inertia and energy dissipation that reduces the resonator’s performance. To minimize the detrimental fluid effects on such devices, a novel microdisk resonator supported by two tangentially-oriented, axially-driven “legs” is investigated analytically and effects of the system parameters on the resonator/sensor performance are explored. Since the device surface vibrates primarily parallel to the fluid-structure interface, it is referred to here as an “all-shear interaction device,” or ASID. Analytical modeling of the ASID …

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 …

Theory, Fabrication, And Experimentation Of Phononic Crystals In Mems At Micro/Nano Scale: Engineering Of Thermal And Rf Phonons To Applications In Thermoelectrics And Microresonators, Seyedhamidreza Alaie

Mechanical Engineering ETDs

Phononic Crystals (PnCs) are novel materials comprised of a periodic structure of inclusions in a matrix. This periodic arrangement creates phononic bandgaps, and modifies phononic bandstructures of a material. Such a property offers promising applications at the micro and nano scales to engineer acoustic filters, high Q-factor resonators, and thermoelectric properties of materials. Studying PnCs at the micro/nano scale requires specific characterization techniques, which rely on Micro Electro Mechanical Structures (MEMS). This work focuses on the study, and characterization of PnCs using MEMS in view of their prospective applications in thermoelectric materials, microresonators and acoustic filters, and also the prospective …

Design, Fabrication, And Testing Of A 3d Printer Based Microfluidic System, Carlton A. Mcmullen

Graduate Theses and Dissertations

A pneumatically actuated PDMS based microfluidic devices were designed and fabricated by soft-lithography. Two types of molds were fabricated out of different material for this experiment. The first mold, (device 1), was fabricated from a sheet of Polymethyl methacrylate (PMMA) material, similar to Plexiglas. The device features were micro-engraved onto the face of the material. The second mold, (device 2), was fabricated from the use of fused deposition modeling (FDM) 3D printing. The pumping efficiency of the PDMS devices was analyzed through the characterization of the micro-pumps flowrate with respect to the pumps driving pressure and the actuation frequency. Tested …

Stochastic Stability And Uncertainty Quantification Of Ring-Based Vibratory Gyroscopes, Soroush Arghavan

Electronic Thesis and Dissertation Repository

Effect of stochastic fluctuations in angular velocity on the stability of two DOF ring-type MEMS gyroscopes is investigated. The governing Stochastic Differential Equations are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of Largest Lyapunov Exponents are employed for validation purposes due to lack of similar analytical or experimental data. The stability investigation predicts that the threshold fluctuation intensity increases nonlinearly with damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear …

Securemems: Selective Deposition Of Energetic Materials, Trevor J. Fleck, Josiah R. Thomas, Lillian F. Miles, Allison K. Murray, Zane A. Roberts, Raghav Ramachandran, I Emre Gunduz, Steven F. Son, George T. Chiu, Jeffrey F. Rhoads

The Summer Undergraduate Research Fellowship (SURF) Symposium

There exists a pressing operational need to secure and control access to high-valued electromechanical systems, and in some cases render them inoperable. Developing a reliable method for depositing energetic materials will allow for the near-seamless integration of electromechanical systems and energetic material, and, in turn, provide the pathway for security and selective destruction that is needed. In this work, piezoelectric inkjet printing was used to selectively deposit energetic materials. Nanothermites, comprising of nanoscale aluminum and nanoscale copper oxide suspended in dimethyl-formamide (DMF), were printed onto silicon wafers, which enabled both thermal and thrust measurements of the decomposing energetic material. Various …

Fabrication Of Magnetic Two-Dimensional And Three-Dimensional Microstructures For Microfluidics And Microrobotics Applications, Hui Li

Theses and Dissertations--Mechanical Engineering

Micro-electro-mechanical systems (MEMS) technology has had an increasing impact on industry and our society. A wide range of MEMS devices are used in every aspects of our life, from microaccelerators and microgyroscopes to microscale drug-delivery systems. The increasing complexity of microsystems demands diverse microfabrication methods and actuation strategies to realize. Currently, it is challenging for existing microfabrication methods—particularly 3D microfabrication methods—to integrate multiple materials into the same component. This is a particular challenge for some applications, such as microrobotics and microfluidics, where integration of magnetically-responsive materials would be beneficial, because it enables contact-free actuation. In addition, most existing microfabrication methods …

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 …

Nanoenabled Microelectromechanical Sensor For Volatile Organic Chemical Detection, Chiara Zuniga, Matteo Rinaldi, Samuel M. Khamis, A. T. Johnson, Gianluca Piazza

Matteo Rinaldi

A nanoenabled gravimetric chemical sensor prototype based on the large scale integration of single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNTs) as nanofunctionalization layer for aluminum nitride contour-mode resonant microelectromechanical (MEM) gravimetric sensors has been demonstrated. The capability of two distinct single strands of DNA bound to SWNTs to enhance differently the adsorption of volatile organic compounds such as dinitroluene (simulant for explosive vapor) and dymethyl-methylphosphonate (simulant for nerve agent sarin) has been verified experimentally. Different levels of sensitivity (17.3 and 28 KHz µm^2/fg) due to separate frequencies of operation (287 and 450 MHz) on the same die have also …

Modeling And Simulation Of Surface Profile Forming Process Of Microlenses And Their Application In Optical Interconnection Devices, Zhengyu Miao

LSU Doctoral Dissertations

Free space micro-optical systems require to integrate microlens array, micromirrors, optical waveguides, beam splitter, etc. on a single substrate. Out-of-plane microlens array fabricated by direct lithography provides pre-alignment during mask fabrication stage and has the advantage of mass manufacturing at low cost. However, this technology requires precise control of the surface profile of microlenses, which is a major technical challenge. The quality control of the surface profile of microlenses limits their applications. In this dissertation, the surface forming process of the out-of-plane microlenses in UV-lithography fabrication was modeled and simulated using a simplified cellular automata model. The microlens array was …

Toward Sophisticated Controls Of Two-Phase Transport At Micro/Nano-Scale, Fanghao Yang

Theses and Dissertations

Through the use of latent heat evaporating, flow boiling in microchannels offers new opportunities to enable high efficient heat and mass transport for a wide range of emerging applications such as high power electric/electronic/optical cooling, compact heat exchangers and reactors. However, flow boiling in microchannels is hampered by several severe constraints such as bubble confinement (e.g., slug flow), viscosity and surface tension force-dominated flows, which result in unpredictable flow pattern transitions and tend to induce severe flow boiling instabilities (i.e. low-frequency and large magnitude flows) and suppress evaporation and convection.

In this dissertation, three novel micro/nanoscale thermo-fluidic control methodologies were …

Development Of Mems-Based Corrosion Sensor, Feng Pan

Graduate Theses and Dissertations

This research is to develop a MEMS-based corrosion sensor, which is used for monitoring uniform, galvanic corrosion occurring in infrastructures such as buildings, bridges. The corrosion sensor is made up of the composite of micro/nano metal particles with elastomers. The mechanism of corrosion sensor is based on the mass transport of corrosive species through the sensor matrix. When the metal particles in the matrix corrode, the electrical resistivity of the material increases due to increasing particle resistances or reduction of conducting pathways. The corrosion rate can be monitored by detecting the resistivity change in sensing elements. The life span of …

Design And Testing Of A Biological Microelectromechanical System For The Injection Of Thousands Of Cells Simultaneously, Gregory Herlin Teichert

Theses and Dissertations

The ability to inject DNA and other foreign particles into cells, both germ cells (e.g. to produce transgenic animals) and somatic cells (e.g. for gene therapy), is a powerful tool in genetic research. Nanoinjection is a method of DNA delivery that combines mechanical and electrical methods. It has proven to have higher cell viability than traditional microinjection, resulting in higher integration per injected embryo. The nanoinjection process can be performed on thousands of cells simultaneously using an array of microneedles that is inserted into a monolayer of cells. This thesis describes the needle array design requirements and the fabrication process …

Fabrication And Characterization Of Torsional Micro-Hinge Structures, Mike Madrid Marrujo

Master's Theses

ABSTRACT

Fabrication and Characterization of Torsional Micro-Hinge Structures

Mike Marrujo

There are many electronic devices that operate on the micrometer-scale such as Digital Micro-Mirror Devices (DMD). Micro actuators are a common type of DMD that employ a diaphragm supported by torsional hinges, which deform during actuation and are critical for the devices to have high stability and reliability. The stress developed within the hinge during actuation controls how the actuator will respond to the actuating force. Electrostatically driven micro actuators observe to have a fully recoverable non-linear viscoelastic response. The device consists of a micro-hinge which is suspended by two …

Mechanical Properties And Mems Applications Of Carbon-Infiltrated Carbon Nanotube Forests, Walter C. Fazio

Theses and Dissertations

This work explores the use of carbon-infiltrated carbon nanotube (CI-CNT) forests as a material for fabricating compliant MEMS devices. The impacts of iron catalyst layer thickness and carbon infiltration time are examined. An iron layer of 7nm or 10nm with an infiltration time of 30 minutes produces CI-CNT best suited for compliant applications. Average maximum strains of 2% and 2.48% were observed for these parameters. The corresponding elastic moduli were 5.4 GPa and 4.1 GPa, respectively. A direct comparison of similar geometry suggested CI-CNT is 80% more flexible than single-crystal silicon. A torsional testing procedure provided an initial shear modulus …

Nanoindentation And Micro-Mechanical Fracture Toughness Of Electrodeposited Nanocrystalline Ni-W Alloy Films

A.S. Md Abdul Haseeb

Nanocrystalline nickel-tungsten alloys have great potential in the fabrication of components for microelectromechanical systems. Here the fracture toughness of Ni-12.7 at.%W alloy micro-cantilever beams was investigated. Micro-cantilevers were fabricated by UV lithography and electrodeposition and notched by focused ion beam machining. Load was applied using a nanoindenter and fracture toughness was calculated from the fracture load. Fracture toughness of the Ni-12.7 at.%W was in the range of 1.49-5.14 MPa √m. This is higher than the fracture toughness of Si (another important microelectromechanical systems material), but considerably lower than that of electrodeposited nickel and other nickel based alloys. © 2012 Elsevier …

Nanoindentation And Micro-Mechanical Fracture Toughness Of Electrodeposited Nanocrystalline Ni-W Alloy Films

A.S. Md Abdul Haseeb

Nanocrystalline nickel-tungsten alloys have great potential in the fabrication of components for microelectromechanical systems. Here the fracture toughness of Ni-12.7 at.%W alloy micro-cantilever beams was investigated. Micro-cantilevers were fabricated by UV lithography and electrodeposition and notched by focused ion beam machining. Load was applied using a nanoindenter and fracture toughness was calculated from the fracture load. Fracture toughness of the Ni-12.7 at.%W was in the range of 1.49-5.14 MPa √m. This is higher than the fracture toughness of Si (another important microelectromechanical systems material), but considerably lower than that of electrodeposited nickel and other nickel based alloys. © 2012 Elsevier …

Low Loss Vhf And Uhf Filters For Wireless Communications Based On Piezoelectrically-Transduced Micromechanical Resonators, Julio Mario Dewdney

USF Tampa Graduate Theses and Dissertations

For the past decade, a great deal of research has been focused towards developing a viable on-chip solution to replace the current state-of-the-art VHF and UHF filters based on SAW and FBAR technologies. Although filters based on SAW and FBAR devices are capable of fulfilling the basic requirements needed for IF and RF bandpass filtering and reference signal generation, an alternative solution that can enable the next generation of multi-frequency and multi-mode transceivers while enabling size and price reduction by allowing the manufacturing of single-chip monolithic RF transceivers is highly desired. In response to these new needs, piezoelectrically-transduced micromechanical filters …

Pdms Based Waveguides For Microfluidics And Eocb, Weiping Qiu

LSU Master's Theses

Due to the low cost, fast and ease of molding, PDMS has become one of the most popular materials for microfluidics devices, bioMEMS applications. Meanwhile, the integration of different functional components on to one single chip (or Lab on a Chip) is the dream for many scientists and engineers in the related area. In addition to the necessary mechanical components for accommodating the reactions, such as pumps, valves, mixers and so on, optical components such as waveguides, lens, interferers are all desired to be lumped into such a system.

The waveguide for such a system requires the material to have …

Devices And Methods For Electro-Physical Transport Of Dna Across Cell Membranes, Quentin Theodore Aten

Theses and Dissertations

A novel method for charged macromolecule delivery, called nanoinjection, has been developed at Brigham Young University. Nanoinjection combines micro-fabrication technology, mechanism design, and nano-scale electrical phenomenon to transport exogenous DNA across cell membranes on a nano-featured lance. DNA is electrically accumulated on the lance, precision movements of microelectromechanical systems (MEMS) physically insert the lance into cell, and DNA is electrically released from the lance into the cell. Penetration into the cell is achieved through a two-phase, self-reconfiguring metamorphic mechanism. The surface-micromachined, metamorphic nanoinjector mechanism elevates the lance above the fabrication substrate, then translates in-plane at a constant height as the …

Modeling, Design, And Testing Of An Underwater Microactuation System Using A Standard Mems Foundry Process, Gregory L. Holst

Theses and Dissertations

This work presents the modeling, design, and testing of an underwater microactuation system. It is composed of several thermomechanical in-plane microactuators (TIM) integrated with a ratchet system to provide long displacements and high forces to underwater microelectromechanical systems (MEMS). It is capable of actuating a 200µN load 110µm. It is a two-layer silicon MEMS device fabricated with a MEMS fabrication process, PolyMUMPS. This work also shows the development of an elliptic integral model to analyze the compliant fixed-guided beams in the TIM and gives new insight into the buckling behavior, reaction forces, and displacement of the beams. The derivation, verification, …

High Frequency Thermally Actuated Single Crystalline Silicon Micromechanical Resonators With Piezoresistive Readout, Amir Rahafrooz

Electronic Theses and Dissertations

Over the past decades there has been a great deal of research on developing high frequency micromechanical resonators. As the two most common and conventional MEMS resonators, piezoelectric and electrostatic resonators have been at the center of attention despite having some drawbacks. Piezoelectric resonators provide low impedances that make them compatible with other low impedance electronic components, however they have low quality factors and complicated fabrication processes. In case of electrostatic resonators, they have higher quality factors but the need for smaller transductions gaps complicates their fabrication process and causes squeezed film damping in Air. In addition, the operation of …

Label-Free Biochemical Recognition Using Mems Resonators For Microarray Technology, Babak Tousifar

Electronic Theses and Dissertations

Highly sensitive biosensors capable of detecting and characterizing smallest quantities of cellular and molecular targets are needed in pharmaceutical and medical diagnostics industries. In this work, the importance of biological target recognition specifically proteins through microarray technologies has been discussed and the most successful tools and techniques have been studied. Moreover, a thermally actuated Micro Electro-Mechanical Systems (MEMS) resonator has been demonstrated and fabricated in this work as an accurate, reliable and low cost biotechnology tool. As a proof of concept, amine to epoxide coupling of octadecylamine to functionalized silicon dioxide surface have been shown through resonator frequency monitoring. The …

Small Footprint High Flow Rate Microdevice For Rare Target Cell Capture, Taehyun Park

LSU Doctoral Dissertations

A novel high flow rate cell capture design was introduced to overcome the limitations of the current technologies or methods for rare target cell capture. Even though the rare target cell capture using BioMEMS technology has great potential for cancer diagnosis, previous rare cell capture research could not overcome the limitations of low flow rate or low recovery rate. Rare cell research requires precise sample preparation for accurate results. A new method of preparation for a single or a precise number of target cell was introduced. Current sample preparation methods which are not suitable for rare cell research, such as …

Modeling And Testing Of Dna Motion For Nanoinjection, Regis Agenor David

Theses and Dissertations

A new technique, called nanoinjection, is being developed to insert foreign DNA into a living cell. Such DNA transfection is commonly used to create transgenic organisms vital to the study of genetics, immunology, and many other biological sciences. In nanoinjection, DNA, which has a net negative charge, is electrically attracted to a micromachined lance. The lance then pierces the cell membranes, and the voltage on the lance is reversed, repelling the DNA into the cell. It is shown that DNA motion is strongly correlated to ion transport through a process called electrophoresis. Gel electrophoresis is used to move DNA using …

Continuous Electrowetting Actuation Utilizing Current Rectification Properties Of Valve Metal Films, Corey M. Lynch

USF Tampa Graduate Theses and Dissertations

Electrowetting on dielectric (EWOD) is a technique for reducing the apparent contact angle of a fluid droplet, which has many promising applications in the fields of optics, digital displays, and lab-on-a-chip research. In this thesis, a design is presented for a novel single circuit device for achieving continuous droplet motion, by using the current-rectifying properties of valve metals to create diode-like behavior. This contrasts with existing designs, which require an array of individual electrodes to achieve motion in discrete steps. We are able to demonstrate continuous droplet motion across a 28mm-long test strip with an applied voltage of 303 V …

Piezoresistive Models For Polysilicon With Bending Or Torsional Loads, Gerrit T. Larsen

Theses and Dissertations

This thesis presents new models for determining piezoresistive response in long, thin polysilicon beams with either axial and bending moment inducing loads or torsional loads. Microelectromechanical (MEMS) test devices and calibration methods for finding the piezoresistive coefficients are also presented for both loading conditions. For axial and bending moment inducing loads, if the piezoresistive coefficients are known, the Improved Piezoresistive Flexure Model (IPFM) is used to find the new resistance of a beam under stress. The IPFM first discretizes the beam into small volumes represented by resistors. The stress that each of these volumes experiences is calculated, and the stress …

Nanoenabled Microelectromechanical Sensor For Volatile Organic Chemical Detection, Chiara Zuniga, Matteo Rinaldi, Samuel M. Khamis, A. T. Johnson, Gianluca Piazza

Matteo Rinaldi

A nanoenabled gravimetric chemical sensor prototype based on the large scale integration of single-stranded DNA (ss-DNA) decorated single-walled carbon nanotubes (SWNTs) as nanofunctionalization layer for aluminum nitride contour-mode resonant microelectromechanical (MEM) gravimetric sensors has been demonstrated. The capability of two distinct single strands of DNA bound to SWNTs to enhance differently the adsorption of volatile organic compounds such as dinitroluene (simulant for explosive vapor) and dymethyl-methylphosphonate (simulant for nerve agent sarin) has been verified experimentally. Different levels of sensitivity (17.3 and 28 KHz µm^2/fg) due to separate frequencies of operation (287 and 450 MHz) on the same die have also …