Digital Commons Network^™

Shape Memory Alloy Capsule Micropump For Drug Delivery Applications, Youssef Mohamed Kotb

Theses and Dissertations

Implantable drug delivery devices have many benefits over traditional drug administration techniques and have attracted a lot of attention in recent years. By delivering the medication directly to the tissue, they enable the use of larger localized concentrations, enhancing the efficacy of the treatment. Passive-release drug delivery systems, one of the various ways to provide medication, are great inventions. However, they cannot dispense the medication on demand since they are nonprogrammable. Therefore, active actuators are more advantageous in delivery applications. Smart material actuators, however, have greatly increased in popularity for manufacturing wearable and implantable micropumps due to their high energy …

Enhanced Fabrication Of Microdroplet Generator Nozzle Arrays: Optimizing Koh Etching For Microfluidic Applications, Hongyu Bai

McKelvey School of Engineering Theses & Dissertations

Ultrasonic microdroplet generators are useful devices with broad applications ranging from aerosolized drug delivery to three-dimensional (3D) printing-based additive manufacturing. One such technology comprises a microfabricated array of nozzles with droplet production driven by a piezoelectric transducer. The present study focuses on refining a critical fabrication step, anisotropic wet etching of pyramidal nozzles using a basic potassium hydroxide (KOH) solution. Given the integral role of nozzle geometry in device operation, high-precision techniques including Reactive Ion Etching (RIE), Deep Reactive Ion Etching (DRIE), and KOH wet etching were employed. A tapering geometry is preferred for acoustic wave focusing and efficient droplet …

Extensional Flows Of Polymer Solutions In Planar Microchannels, Mahmud Kamal Raihan

All Dissertations

Non-Newtonian fluids such as polymer solutions often flow under microscale extensional conditions in many natural and engineering flow fields such as in microfluidic chips, porous rocks, biological membranes and filters, printheads in additive manufacturing, etc. The changing cross sectional areas of the internal flow passages therein exert additional extension on the flow along with the shearing. Numerous studies have been dedicated to understanding the extensional flows of polymer solutions over the years. However, most of these studies only focused on flexible polymers exhibiting elasticity in their macroscopic rheology, whereas rigid polymers that portray shear-thinning but often elude elasticity in the …

The Development Of A Primer Payload With Microparticles For Uti Pathogen Identification Using Polythymidine- Modified Lamp Primers In Droplet Lamp, Jonas Otoo

KGI Theses and Dissertations

Nucleic acid amplification tests (NAATs) are among the diagnostic tests with the highest sensitivity and specificity. However, they are more complex to develop than other diagnostic tests such as biochemical tests and lateral flow immunoassay tests. Polymerase chain reaction (PCR) is the gold standard for NAATs. PCR requires thermal cycling to achieve clonal amplification of the target pathogen DNA for diagnosis. Thermal cycling poses a challenge in the development of PCR diagnostics for point-of-care (POC) settings. Loop-mediated isothermal amplification (LAMP) offers an isothermal method for NAATs diagnostics. The advancement of the microfluidics field significantly enhances the development of LAMP diagnostics …

A 3d Bioprinted Hydrogel Microfluidic Device For Screening Applications, Anant Bhusal

Theses and Dissertations

The microfluidic enabled the integration of engineered miniaturized tissue models for drug screening. Conventional polydimethylsiloxane or plastic-based devices require multiple fabrication steps, which are challenging. We developed a 3D bioprinting approach to create prototypes of hydrogel-based multi-material microfluidic devices integrated with microtissue models. The approach utilizes poly(ethylene glycol) diacrylate and gelatin-methacryloyl to create microfluidic chips using multi-material bioprinting capacity with a high resolution of 15µm on x-y and 50µm on the z-axis and post-printing viability of >90%. We demonstrated easy regulation of stiffness from 24±5 kPa to 1,180±9 kPa and burst pressure from 16±1kPa to 256±19 kPa in the chip …

Concentration Field Based Micropore Flow Rate Measurements, Matia P. Edwards, Samuel F. D. J. Gómez, Michael S. H. Boutilier

Chemical and Biochemical Engineering Publications

Demand is growing for a larger catalogue of experimental techniques to measure flow rates through micro-/nanoscale systems for both fundamental research and device development. Flow emerging from a hole in a plane wall is a common system of interest in such work for its relevance to membrane separation. In this paper, we consider the possibility of measuring volume flow rates through small scale orifice plates from images of dye dispersions downstream. Based on approximate analytical solutions to the advection–diffusion equation, we show that, at low Reynolds numbers, the concentration in the nearly hemispherical plume that forms increases linearly with inverse …

Pneumatic Latched Demultiplexer Circuit For Controlling Multi-Actuator Soft Robots, Arsh Noor Amin

Master’s Theses

This thesis presents a novel method for controlling multi-actuator soft robots using pneumatic latched demultiplexer circuits implemented with monolithic membrane valves. The pneumatic circuits are designed to address the problems of heavy dependence on hard electrical components and lack of feasible multi-actuator soft robotic systems that limit the potential applications of soft robotics. The proposed pneumatic demultiplexers reduce the number of solenoid valves and electrical components required to drive soft robotic systems, making soft robot control mechanisms more compliant, scalable, and versatile. The thesis demonstrates the design, fabrication, and testing of 4-bit and n-bit pneumatic demultiplexer circuits that can control …

Numerical Study Of The Time-Periodic Electroosmotic Flow Of Viscoelastic Fluid Through A Short Constriction Microchannel, Jianyu Ji, Shizhi Qian, Armani Marie Parker, Xiaoyu Zhang

Mechanical & Aerospace Engineering Faculty Publications

Electroosmotic flow (EOF) is of utmost significance due to its numerous practical uses in controlling flow at micro/nanoscales. In the present study, the time-periodic EOF of a viscoelastic fluid is statistically analyzed using a short 10:1 constriction microfluidic channel joining two reservoirs on either side. The flow is modeled using the Oldroyd-B (OB) model and the Poisson-Boltzmann model. The EOF of a highly concentrated polyacrylamide (PAA) aqueous solution is investigated under the combined effects of an alternating current (AC) electric field and a direct current (DC) electric field. Power-law degradation is visible in the energy spectra of the velocity fluctuations …

Topologically Optimized Electrodes For Electroosmotic Actuation, Jianwen Sun, Jianyu Zhang, Ce Guan, Teng Zhou, Shizhi Qian, Yongbo Deng

Mechanical & Aerospace Engineering Faculty Publications

Electroosmosis is one of the most used actuation mechanisms for the microfluidics in the current active lab-on-chip devices. It is generated on the induced charged microchannel walls in contact with an electrolyte solution. Electrode distribution plays the key role on providing the external electric field for electroosmosis, and determines the performance of electroosmotic microfluidics. Therefore, this paper proposes a topology optimization approach for the electrodes of electroosmotic microfluidics, where the electrode layout on the microchannel wall can be determined to achieve designer desired microfluidic performance. This topology optimization is carried out by implementing the interpolation of electric insulation and electric …

A Nanofiber-Embedded Microfluidic Platform For Studying Neurobiology, Donghee Lee, Navatha Shree Sharma, S. M. Shatil Shahriar, Kai Yang, Zheng Yan, Jingwei Xie

Department of Mechanical and Materials Engineering: Faculty Publications

Due to their biomimetic properties, electrospun nanofibers have been widely used in neurobiology studies. However, mechanistic understanding of cell-nanofiber interactions is challenging based on the current in vitro culture systems due to the lack of control of spatiotemporal patterning of cells and difficulty in monitoring single cell behavior. To overcome these issues, we apply microfluidic technology in combination with electrospun nanofibers for in vitro studies of interactions between neurons and nanofiber materials. We demonstrate a unique nanofiber embedded microfluidic device which contains patterned aligned or random electrospun nanofibers as a new culture system. With this device, we test how different …

Editorial For The Special Issue On Micromachines For Non-Newtonian Microfluidics, Lanju Mei, Shizhi Qian

Mechanical & Aerospace Engineering Faculty Publications

In lieu of an abstract, this is an excerpt from the first page.

Microfluidics has seen a remarkable growth over the past few decades, with its extensive applications in engineering, medicine, biology, chemistry, etc [...]

The Study Of 3d Micro-Fluid Printing In Aqueous Two-Phase System, Mian Huang

Dissertations and Theses

Aqueous two-phase system (ATPS) is a technology that allows phase separation in an aqueous environment. This technology can be used for the separation, extraction and purification of a variety of biomolecules and thus gained great attention in industry and academia. This thesis is a combination of ATPS, 3D printing, and microfluidics technologies and realizes the printing of biocompatible aqueous structures in another aqueous matrix. The objectives of this thesis include 1) customizing a regular thermal extrusion 3D printer for printing 3D aqueous structures, 2) printing 3D aqueous structure in an aqueous matrix, and 3) studying the stability of the printed …

The Ejection Of Large Non-Oscillating Droplets From A Hydrophobic Wedge In Microgravity, Logan Torres, Mark M. Weislogel

Mechanical and Materials Engineering Faculty Publications and Presentations

When confined within containers or conduits, drops and bubbles migrate to regions of minimum energy by the combined effects of surface tension, surface wetting, system geometry, and initial conditions. Such capillary phenomena are exploited for passive phase separation operations in micro-fluidic devices on earth and macro-fluidic devices aboard spacecraft. Our study focuses on the migration and ejection of large inertial-capillary drops confined between tilted planar hydrophobic substrates (a.k.a., wedges). In our experiments, the brief nearly weightless environment of a 2.1 s drop tower allows for the study of such capillary dominated behavior for up to 10 mL water drops with …

The Draining Of Capillary Liquids From Containers With Interior Corners Aboard The Iss, Joshua Thomas Mccraney, Mark M. Weislogel, Paul Steen

Mechanical and Materials Engineering Faculty Publications and Presentations

In this work, we analyze liquid drains from containers in effective zero-g conditions aboard the International Space Station (ISS). The efficient draining of capillary fluids from conduits, containers, and media is critical in particular to high-value liquid samples such as minuscule biofluidics processing on earth and enormous cryogenic fuels management aboard spacecraft. The amount and rate of liquid drained can be of key concern. In the absence of strong gravitational effects, system geometry, and liquid wetting dominate capillary fluidic behavior. During the years 2010–2015, NASA conducted a series of handheld experiments aboard the ISS to observe “large” length scale capillary …

Development Of A Pneumatically Controllable Microdroplet Generator With Electrical Sensing, Gnanesh Nagesh

Electronic Theses and Dissertations

Microfluidic droplet generation is popular in lab-on-a-chip based biochemical analysis because it can provide precise and high throughput fluids in the form of small droplets. This thesis presents a T-junction microdroplet generator with pneumatic actuation for regulating droplet size and a capacitance-based sensor with real-time sensing capability for characterizing droplet composition and size. The multi-layer device developed in this thesis is compatible with rapid manufacturing using a desktop-based laser cutter to fabricate the fluidic and pneumatic layers. A finite element based numerical model was developed to predict the best operating and geometric parameters for droplet generation. It was revealed that …

Understanding The Interactions Between Acoustic Fields And Motile Microorganisms In Microfluidic Systems, Minji Kim

McKelvey School of Engineering Theses & Dissertations

Acoustofluidics utilizes ultrasonic standing waves in microscale fluidic channels to manipulate cells, microorganisms, and other objects sized from tens of nanometers to tens of microns. When exposed to an ultrasonic standing wave field, particles suspended in a fluid become confined to potential minima (nodes) of the acoustic field. I will present a number of related studies that involve the interactions between acoustic fields and motile microorganisms. First, I will show how an acoustic trap-and-release method enables rapid quantification of cell motility. As a demonstration, the newly developed motility assay is applied to discriminate swimming of wild-type and mutant Chlamydomonas reinhardtii …

Electroosmotic Flow Of Viscoelastic Fluid Through A Constriction Microchannel, Jianyu Ji, Shizhi Qian, Zhaohui Liu

Mechanical & Aerospace Engineering Faculty Publications

Electroosmotic flow (EOF) has been widely used in various biochemical microfluidic applications, many of which use viscoelastic non-Newtonian fluid. This study numerically investigates the EOF of viscoelastic fluid through a 10:1 constriction microfluidic channel connecting two reservoirs on either side. The flow is modelled by the Oldroyd-B (OB) model coupled with the Poisson–Boltzmann model. EOF of polyacrylamide (PAA) solution is studied as a function of the PAA concentration and the applied electric field. In contrast to steady EOF of Newtonian fluid, the EOF of PAA solution becomes unstable when the applied electric field (PAA concentration) exceeds a critical value for …

Microfluidics Design Considering Hyperuniformity And Cell Transport In Flow For Improved Circulating Tumor Cell Capture Efficiency, Michael Clarence Hood

Graduate Research Theses & Dissertations

Isolation of circulating tumor cells (CTCs) from patient derived blood samples for cancerdiagnostics and monitoring is challenging due to the extremely low CTC concentration. This thesis work evaluates the performance of passive microfluidics devices with different designs based on computational modeling. A new cell separation method is proposed based on velocity differentiation of varying cell sizes. All numerical studies were conducted in 2D based on a fluid structure interaction code where the fluid flow was solved based on the lattice Boltzmann method (LBM) implemented in Palabos, and the cell dynamics were simulated based on the molecular dynamics package LAMMPS, with …

Dynamic Behavior And Interactions Of Ferrofluid Droplets Under Magnetic Fields In Low Reynolds Number Flows, Md Rifat Hassan

Doctoral Dissertations

Digital microfluidics in combination with emulsion microfluidics are crucial building blocks of droplet-based microfluidics, which are prevalent in a wide variety of industrial and biomedical applications, including polymer processing, food production, drug delivery, inkjet printing, and cell-based assays. Therefore, understanding the dynamics and interactions of droplets as well as the interactions between the droplets and solid surfaces are of great importance in order to improve the performance or product in these applications.

Recently, several studies in the literature have demonstrated the potential of magnetic fields in controlling the behavior of droplets in microscale; however, the fundamental mechanism behind the interesting …

Centrifugal Microfluidic Platform For Solid-Phase-Extraction (Spe) And Fluorescence Detection Applications, Yong Zhang

LSU Doctoral Dissertations

Solid phase extraction (SPE) is a widely used method to separate and concentrate the target molecules in liquid mixture. Traditional SPE has to be conducted in the laboratory with professional equipment and skilled operators. The microfluidic and 3D printing technology have opened up the opportunity in developing miniaturized automatic instruments. The main contribution of this research is to integrate the SPE process on a novel centrifugal platform. Various valves are applied on the platform to help control the aqueous sample and reagents in the cartridge.

First, a centrifugal microfluidic platform was built for automatically detecting trace oil pollution in water. …

Planar Corrugated Electrode Configuration For Manipulation Of Micro-Scale Entities In Dielectrophoretic Microfluidic Devices, Alia Mohammed Alblooshi

Mechanical Engineering Theses

This thesis conceptualizes the design of a planar electrode for employment in microfluidic devices to achieve dielectrophoretic focusing and separation of micro-scale entities. The planar electrode has corrugations with two such electrodes placed parallelly to form a pair and the electric field is generated between them; the presence of corrugations enhances the non-uniformity of the electric field. For purposes of 3D focusing, two pairs of electrodes are used with each pair on both sides of the microchannel. When the applied electric voltages are equal, the micro-scale entity is focused at the center of the microchannel and when the applied electric …

Bioprinted In Vitro Model Of Human Glioblastoma, Rachel Lauren Schwartz

Theses and Dissertations

Glioblastoma multiform (GBM) is one of the most aggressive forms of primary brain tumors. GBM is fast progressing and resistant to treatment, resulting in a low survival rate. Conventional 2-dimensional tissue culture models cannot fully replicate the complexities of cancer lesions that contain multiple cell types and structures (e.g. vessels composed of endothelial cells, cancer cells, normal cells, etc.) as well as an intricate scaffold of proteins comprising the extracellular matrix (ECM). In addition, animal models cannot translate into the clinical disease in patients. Thus, this study has developed a bioprintable organ-on-a-chip (OOAC) model that mimics the important ECM factors …

Inverted Fluorescence Microscope, Makenzie Lyn Kamei, Enoch Wright Nicholson, Eduardo Reyna Miranda Jr., Trevor John Brown

Mechanical Engineering

The Inverted Fluorescence Microscope senior project team at Cal Poly, San Luis Obispo designed, assembled, and tested a proof-of-concept inverted fluorescence microscope for the university’s Microfabrication Laboratory. Administrators of the laboratory wished to use fluorescence for research and experiments involving cell growth and flow visualization on the micro-scale, and did not have the budget to purchase one of the costly commercially available options. The scope of this design challenge was to produce a low-cost inverted fluorescence microscope employing available optical components and additional readily sourced parts to expand the use of fluorescence microscopy accessible to undergraduate students in the Microfabrication …

Fabrication Of Hard–Soft Microfluidic Devices Using Hybrid 3d Printing, Carlos Ruiz, Karteek Kadimisetty, Kun Yin, Michael G. Mauk, Hui Zhao, Changchun Liu

Mechanical Engineering Faculty Research

Widely accessible, inexpensive, easy-to-use consumer 3D printers, such as desktop stereolithography (SLA) and fused-deposition modeling (FDM) systems are increasingly employed in prototyping and customizing miniaturized fluidic systems for diagnostics and research. However, these 3D printers are generally limited to printing parts made of only one material type, which limits the functionality of the microfluidic devices without additional assembly and bonding steps. Moreover, mating of different materials requires good sealing in such microfluidic devices. Here, we report methods to print hybrid structures comprising a hard, rigid component (clear polymethacrylate polymer) printed by a low-cost SLA printer, and where the first printed …

Magnetic Control Of Transport Of Particles And Droplets In Low Reynolds Number Shear Flows, Jie Zhang

Doctoral Dissertations

“Magnetic particles and droplets have been used in a wide range applications including biomedicine, biological analysis and chemical reaction. The manipulation of magnetic microparticles or microdroplets in microscale fluid environments is one of the most critical processes in the systems and platforms based on microfluidic technology. The conventional methods are based on magnetic forces to manipulate magnetic particles or droplets in a viscous fluid.

In contrast to conventional magnetic separation method, several recent experimental and theoretical studies have demonstrated a different way to manipulate magnetic non-spherical particles by using a uniform magnetic field in the microchannel. However, the fundamental mechanism …

Openfoam Simulations Of Late Stage Container Draining In Microgravity, Joshua Thomas Mccraney, Mark M. Weislogel, Paul Steen

Mechanical and Materials Engineering Faculty Publications and Presentations

In the reduced acceleration environment aboard orbiting spacecraft, capillary forces are often exploited to access and control the location and stability of fuels, propellants, coolants, and biological liquids in containers (tanks) for life support. To access the ‘far reaches’ of such tanks, the passive capillary pumping mechanism of interior corner networks can be employed to achieve high levels of draining. With knowledge of maximal corner drain rates, gas ingestion can be avoided and accurate drain transients predicted. In this paper, we benchmark a numerical method for the symmetric draining of capillary liquids in simple interior corners. The free surface is …

Longitudinal Acoustic Traps: Design, Fabrication, And Evaluation For Biological Applications, Michael Moore Binkley

McKelvey School of Engineering Theses & Dissertations

Acoustofluidics combine ultrasonic actuation with small-volume microfluidic channels to enable precise, contactless object manipulation for a range of applications from serial chemical processing to blood component separation and single-cell analysis. Micron- to millimeter-scale vibrational waves generate reproducible pressure fields within the microfluidic channels and chambers. By exploiting the material property mismatch between a particle (polymeric and silica beads, cells, etc.) and a suspending fluid, the acoustic radiation force is used to move particles toward regions of low (nodes) or high pressure (antinodes). An understanding of these field-particle interactions is applied to design and implement complicated channel architectures for preferential segregation …

Passive Separation Of Binary Fluid Mixtures In Microchannels Using Lattice Boltzmann Method, Mohanad Kamil Radhi

Dissertations and Theses

Fluid mixtures in real life exist in two forms: miscible and immiscible. Separation of these mixtures using chemical agents or thermal energy has both environmental and economic disadvantages. The high cost and the environmental damage caused by the traditional separation techniques have stimulated both academia and industry to seek alternatives. The emergence of microfluidics offers robust solutions for a broad span of transport problems due to the high surface to volume ratio and reduced length scales. Particularly, the separation efficiency increases significantly due to the aforementioned feature. However, there is still a pressing need of passive separations for the sake …

Investigation Of Dielectrophoretic Microfluidic Trap System For Separation And Parallel Analysis Of Single Particles, Tae Joon Kwak

Theses and Dissertations

Separation and identification of single molecules and particles based on their chemical, biochemical and physical properties are critical in wide range of biomedical applications. Manipulating a single biomolecule requires sensitive approaches to avoid damage to the molecule. Recent progress in micro- and nano-technology enabled the development of various novel methods and devices to trap, separate, and characterize micro- and nano-particles. In this dissertation, a microfluidic particle trap system to electrically separate particles at the single particle level was developed through particle manipulation methods using dielectrophoresis. The research in this dissertation will explain the operation strategy and setup of the novel …

3d Printing A Microfluidic Chip Capable Of Droplet Emulsion Using Ninjaflex Filament, Robert Andrews

Mechanical Engineering Undergraduate Honors Theses

This paper details an investigation into methods and designs of 3D printing a microfluidic system capable of droplet emulsion using NinjaFlex filament. The specific field in which this paper’s experiment is rooted is dubbed “BioMEMS,” short for bio microelectromechanical systems. One prominent research area in BioMEMS is developing a “lab on a chip.” Essentially, the goal is to miniaturize common lab processes to the micro scale, rendering it possible to include these processes in a small chip. Reducing necessary sample sizes, shortening the reaction times of lab processes, and increasing mobility of lab processes can all be realized through microfluidic …