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University of Houston
1.
He, Guoliang.
Investigation of Dielectrophoresis-directed Fluidic Assembly.
Degree: PhD, Mechanical Engineering, 2015, University of Houston
URL: http://hdl.handle.net/10657/1979 
► Dielectrophoresis (DEP)-based fluidic self-assembly of nanoscale building blocks, such as nanoparticles and nanowires, is a promising alternative to the current micro/nanofabrication techniques to manufacture functional…
(more)
▼ Dielectrophoresis (DEP)-based fluidic self-assembly of nanoscale building blocks, such as nanoparticles and nanowires, is a promising alternative to the current micro/nanofabrication techniques to manufacture functional micro/nanodevices. While individual particles can be manipulated with reasonable precision, it remains a grand challenge to scale up the assembly process to reproducibly assemble a large number of particles. This is partially due to the lack of a quantitative understanding of the complex fluid-particle dynamics when numerous nanostructures are interacting both electrically and hydrodynamically. In this work, both experiment and numerical study were conducted to explore the electrohydrodynamic effects during the assembly of multiple nanostructures driven by DEP.
Direct numerical simulations were conducted that combine the Maxwell Stress Tensor (MST) approach and the Distributed Lagrange Multiplier/Fictitious Domain (DLM/FD) method to solve the conjugate fluid-particle interaction problem. The MST approach was used to compute the DEP forces and torques exerted on the particles, which yields rigorous solutions even for highly non-uniform electric field and for particles of irregular shapes. The DLM/FD method was then employed to simulate the hydrodynamic equations of the particle-fluid system involving multiple particles. The motion of the individual particles and the subsequent aggregation of adjacent particles under three major driving mechanisms for directed self-assembly, namely, DEP, traveling-wave DEP and electrorotation, were studied in details. In addition, microfluidic DEP devices were fabricated and self-assembly experiments were carried out for polystyrene microparticles suspended in colloidal solutions. The observed particle motion and the assembly patterns were compared to the numerical simulation results. The good agreement suggests the comprehensive numerical framework developed in this work can be used as a powerful tool for the fundamental study of colloidal hydrodynamics with coupled electrokinetic effects.
With further advancement, this work will help to push forward the development of more effective and robust fluidic assembly techniques, and lay the foundation towards large-scale parallel manufacturing of functional nanostructures for various engineering applications.
Advisors/Committee Members: Liu, Dong (advisor), Pan, Tsorng-Whay (committee member), Franchek, Matthew A. (committee member), Mavrokefalos, Anastassios (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Dielectrophoresis; Fluidic assembly; Distributed Lagrange multiplier; Fictitious domain method; Maxwell stress
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APA (6th Edition):
He, G. (2015). Investigation of Dielectrophoresis-directed Fluidic Assembly. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/1979
Chicago Manual of Style (16th Edition):
He, Guoliang. “Investigation of Dielectrophoresis-directed Fluidic Assembly.” 2015. Doctoral Dissertation, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/1979.
MLA Handbook (7th Edition):
He, Guoliang. “Investigation of Dielectrophoresis-directed Fluidic Assembly.” 2015. Web. 19 Jan 2021.
Vancouver:
He G. Investigation of Dielectrophoresis-directed Fluidic Assembly. [Internet] [Doctoral dissertation]. University of Houston; 2015. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/1979.
Council of Science Editors:
He G. Investigation of Dielectrophoresis-directed Fluidic Assembly. [Doctoral Dissertation]. University of Houston; 2015. Available from: http://hdl.handle.net/10657/1979
University of Houston
2.
-2365-2381.
Elastomer Degradation in Chemically Reactive Environment under Elevated Temperature and Pressurized Condition.
Degree: PhD, Materials Engineering, 2017, University of Houston
URL: http://hdl.handle.net/10657/4771
► Mechanical properties of elastomer undergo accelerated degradation when immersed in chemically active environment, especially at elevated temperature and/or under high pressure. Beside physical relaxation due…
(more)
▼ Mechanical properties of elastomer undergo accelerated degradation when immersed in chemically active environment, especially at elevated temperature and/or under high pressure. Beside physical relaxation due to the viscoelastic nature of polymers, diffusion-reaction process plays an important role in accelerating elastomer deterioration.
In a previous research, Fickian diffusion was often used to model the small molecule ingression in bulk elastomeric materials. Under high temperature and high pressure, chemical reaction accelerates and some of the processes that are negligible under standard temperature and pressure can have significant impacts on elastomer properties. For example, water near or above its critical state, can react with some relatively stable functional groups in elastomers.
To study elastomer degradation under HPHT and chemical environment, sealed mechanical testing apparatuses have been designed and manufactured so that real time mechanical performance of elastomer under compression after ageing in chemicals, at elevated temperature, and under pressurized conditions, can be quantitatively studied. It is found that for elastomer stress relaxation, additional lateral confinement induced by environmental stress can effective reduce elastomer relaxation along the axial direction.
In addition to the development of experimental elastomer characterization methodology, we also built a quantitative model to investigate the diffusion-reaction process between chemical diffusant and elastomer at elevated temperature and under pressurized condition. The PDE developed in this study uses the Vrentus-Duda free volume theory to quantify the diffusion between small molecules and macromolecular matrices. Current model allows us to study temperature, pressure, and chemical kinetic effects through the quantification of diffusant concentration profile evolvement numerically by solving the PDE problem.
Finally, we also studied the electromechanical properties of an elastomer-carbon nanocomposite. The nanocomposite are fabricated by a solution casting technique based on a patent from our research group to achieve high quality interfacial bonding and uniform filler distribution. Electromechanical behavior in such elastomer nanocomposite is studied, repeatable piezoresistive response is confirmed after training cycles, and their potential applications as large deformation strain sensor are discussed.
Advisors/Committee Members: Sun, Li (advisor), Franchek, Matthew A. (committee member), Mo, Yi-Lung (committee member), Ardebili, Haleh (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Elastomer; Ageing; Diffusion-reaction process; Free volume theory; Affine network model
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APA (6th Edition):
-2365-2381. (2017). Elastomer Degradation in Chemically Reactive Environment under Elevated Temperature and Pressurized Condition. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4771
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-2365-2381. “Elastomer Degradation in Chemically Reactive Environment under Elevated Temperature and Pressurized Condition.” 2017. Doctoral Dissertation, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/4771.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-2365-2381. “Elastomer Degradation in Chemically Reactive Environment under Elevated Temperature and Pressurized Condition.” 2017. Web. 19 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-2365-2381. Elastomer Degradation in Chemically Reactive Environment under Elevated Temperature and Pressurized Condition. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/4771.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-2365-2381. Elastomer Degradation in Chemically Reactive Environment under Elevated Temperature and Pressurized Condition. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4771
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Houston
3.
-9808-7137.
Development of Analytical Models for Evaluating the Mechanical and Electrochemical Response of Flexible and Stretchable Lithium Ion Battery Materials.
Degree: PhD, Materials Engineering, 2016, University of Houston
URL: http://hdl.handle.net/10657/5385
► Flexible and stretchable batteries have become a highly active area of research in recent years due to a new demand for mechanically compliant energy storage…
(more)
▼ Flexible and stretchable batteries have become a highly active area of research in recent years due to a new demand for mechanically compliant energy storage devices for a wide range of flexible applications including wearable and implantable electronics, touch-screens, and smart technology. Lithium ion batteries are leading candidates for flexible and stretchable energy storage devices due to their high energy density and efficiency. Considerable research has been related to developing flexible and stretchable materials, and solid polymer electrolyte lithium ion batteries show promise, offering many mechanical and safety advantages. While much experimental work has been in the development of these batteries, considerably less analytical modeling and numerical work has been a part of the development, which would elucidate experimental observations and provide enhanced understanding of the materials behavior in these new batteries. The work presented in this dissertation includes results of computational modeling and simulation of the mechanical and electrochemical behavior of flexible and stretchable battery materials under normal operating conditions and applied deformations resulting from mechanical loads. Additionally, analytical multiphysics models in the form of series of differential equations were derived to explain experimental observations of changes in battery performance and material properties due to applied loads and deformations. These models can be used to predict materials behavior and to relate key design parameters of flexible and stretchable batteries. The battery materials and designs that are assessed in this work were developed in our lab. Objectives of this work include understanding relationships between mechanical loading and certain key controllable fabrication parameters such as layer interface contact properties to predict the influence on flexible battery performance, and exploring how deformation occurring in the polymer electrolyte due to an applied mechanical load influences electrochemical performance. The effect of loading on other performance parameters, including battery impedance, is further studied, and all analytical work is compared to experimental data. An important aspect of this development is the consideration of nonlinearity in the models. Novel approaches are taken to include and address nonlinearity within the systems considered. While these models can be simplified through linearization, limitations of linear solutions are also discussed.
Advisors/Committee Members: Ardebili, Haleh (advisor), Ryou, Jae-Hyun (committee member), Yu, Cunjiang (committee member), Sharma, Pradeep (committee member), Kulkarni, Yashashree (committee member).
Subjects/Keywords: Flexible batteries; Batteries; Lithium-ion batteries (LIB); Stretchable lithium ion batteries; Nonlinear modeling
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APA (6th Edition):
-9808-7137. (2016). Development of Analytical Models for Evaluating the Mechanical and Electrochemical Response of Flexible and Stretchable Lithium Ion Battery Materials. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/5385
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Chicago Manual of Style (16th Edition):
-9808-7137. “Development of Analytical Models for Evaluating the Mechanical and Electrochemical Response of Flexible and Stretchable Lithium Ion Battery Materials.” 2016. Doctoral Dissertation, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/5385.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
MLA Handbook (7th Edition):
-9808-7137. “Development of Analytical Models for Evaluating the Mechanical and Electrochemical Response of Flexible and Stretchable Lithium Ion Battery Materials.” 2016. Web. 19 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Vancouver:
-9808-7137. Development of Analytical Models for Evaluating the Mechanical and Electrochemical Response of Flexible and Stretchable Lithium Ion Battery Materials. [Internet] [Doctoral dissertation]. University of Houston; 2016. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/5385.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
Council of Science Editors:
-9808-7137. Development of Analytical Models for Evaluating the Mechanical and Electrochemical Response of Flexible and Stretchable Lithium Ion Battery Materials. [Doctoral Dissertation]. University of Houston; 2016. Available from: http://hdl.handle.net/10657/5385
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
University of Houston
4.
Lu, Yi.
Electrowetting Enhancement of Critical Heat Flux.
Degree: PhD, Mechanical Engineering, 2017, University of Houston
URL: http://hdl.handle.net/10657/4614
► Critical heat flux (CHF) represents the upper limit of nucleate boiling heat transfer, beyond which boiling transitions to the inefficient film boiling regime. Potentially catastrophic…
(more)
▼ Critical heat flux (CHF) represents the upper limit of nucleate boiling heat transfer, beyond which boiling transitions to the inefficient film boiling regime. Potentially catastrophic burnout conditions may ensue and endanger the safe and reliable operation of the boiling device. Thus, it is highly desirable to augment CHF in order to boost the thermal performance of various energy-intensive applications that rely on boiling to transport a large amount of thermal energy.
In this work, CHF enhancement was explored both theoretically and experimentally by capitalizing on the ability of electrowetting (EW) to modulate the liquid-vapor interfacial stabilities and the liquid-vapor-solid three-phase contact line motion. To do so, a Leidenfrost drop (i.e., a liquid drop hovering over a highly superheated solid surface) was first employed as a model system, due to its simplicity and close connection to film boiling and CHF, to investigate the effect of the electric field on the dynamics of the vapor film that separates the drop from the hot surface. It was found that the electrostatic attraction force alone cannot destabilize the vapor film, instead, it is the accelerated vapor flow that changes the critical wavelength of the Kelvin-Helmholtz instability, thus causing the film to collapse. The results show that, without the need for any complicated surface micro/nanostructures, the Leidenfrost point (LFP) temperature of water can be increased from 200°C to 380°C with a moderate voltage of 56 V a frequency of 50 Hz.
Subsequently, to better understand the impact of EW on the liquid-vapor interfacial behaviors, the dynamics of EW-induced motion of both liquid droplets and vapor bubbles was studied. Computational fluid dynamics models were developed by using the Volume of Fluid (VOF)-Continuous Surface Force (CSF) method to scrutinize the response of a droplet when subject to EW actuating signals. In particular, a dynamic contact angle model based on the molecular kinetic theory was implemented as the boundary condition at the moving contact line, which considers the effects of both the contact line friction and the pinning force. The droplet shape evolution and the interfacial resonance oscillation were investigated in detail. On the bubble aspect, the nucleation, growth and departure of vapor bubbles on a hydrophilic surface, a hydrophobic surface both with and without the influence of EW, were compared, which revealed the significant effect of the EW force on the contact line and, therefore, on the bubble dynamics.
Lastly, to demonstrate the EW enhancement of CHF, a synchronized high-speed optical imaging and infrared (IR) thermographic technique was used to characterize boiling heat transfer at the CHF conditions. Simultaneous measurements of the bubble dynamics and the wall temperature and heat flux distributions on the boiling surface were acquired. The results showed that CHF can be enhanced by 133% by the use of EW. Additionally, by considering the force balance at the contact line of a nucleate…
Advisors/Committee Members: Liu, Dong (advisor), Ruchhoeft, Paul (committee member), Mavrokefalos, Anastassios (committee member), Ghasemi, Hadi (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Electrowetting; Critical heat flux; Boiling
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APA (6th Edition):
Lu, Y. (2017). Electrowetting Enhancement of Critical Heat Flux. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/4614
Chicago Manual of Style (16th Edition):
Lu, Yi. “Electrowetting Enhancement of Critical Heat Flux.” 2017. Doctoral Dissertation, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/4614.
MLA Handbook (7th Edition):
Lu, Yi. “Electrowetting Enhancement of Critical Heat Flux.” 2017. Web. 19 Jan 2021.
Vancouver:
Lu Y. Electrowetting Enhancement of Critical Heat Flux. [Internet] [Doctoral dissertation]. University of Houston; 2017. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/4614.
Council of Science Editors:
Lu Y. Electrowetting Enhancement of Critical Heat Flux. [Doctoral Dissertation]. University of Houston; 2017. Available from: http://hdl.handle.net/10657/4614
5.
Wu, Tingcheng.
DESIGN AND ANALYSIS OF THE ROTOR OF A FULLY SUPERCONDUCTING MACHINE.
Degree: MS, Mechanical Engineering, 2014, University of Houston
URL: http://hdl.handle.net/10657/1454
► Because of their very high specific torque, fully superconducting rotating machines are considered as enabling technology for future turbo-electric propulsion for transportation aircraft. NASA is…
(more)
▼ Because of their very high specific torque, fully superconducting rotating machines are considered as enabling technology for future turbo-electric propulsion for transportation aircraft. NASA is funding the development of a high fidelity fully superconducting machine sizing tool able to generate optimized designs based on power requirements and design constraints.
In this thesis, a mechanical model of a rotor of fully superconducting motor with 4MW Power and 5000 RPM speed is designed. The model developed includes a realistic 3D geometry representation and is based on parametric design methods. COMSOL MultiPhysics has been used to validate the mechanical calculations including the thermal stress, strain, displacement and torque induced stress and deformation. This parametric model allows us to get the relationship between stress/strain and a series of parameters. This will help define the most proper materials and topology considering different required working conditions. The simulations allowed for a full characterization of the superconducting motor composite shaft and successfully validated the analytical estimation of the stress and deformation of the shaft and stator during cool down and under the effect of the applied torque.
Advisors/Committee Members: Masson, Philippe J. (advisor), Song, Gangbing (committee member), Provence, Robert S. (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Fully superconducting machine; Design; ANALYZE
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APA (6th Edition):
Wu, T. (2014). DESIGN AND ANALYSIS OF THE ROTOR OF A FULLY SUPERCONDUCTING MACHINE. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/1454
Chicago Manual of Style (16th Edition):
Wu, Tingcheng. “DESIGN AND ANALYSIS OF THE ROTOR OF A FULLY SUPERCONDUCTING MACHINE.” 2014. Masters Thesis, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/1454.
MLA Handbook (7th Edition):
Wu, Tingcheng. “DESIGN AND ANALYSIS OF THE ROTOR OF A FULLY SUPERCONDUCTING MACHINE.” 2014. Web. 19 Jan 2021.
Vancouver:
Wu T. DESIGN AND ANALYSIS OF THE ROTOR OF A FULLY SUPERCONDUCTING MACHINE. [Internet] [Masters thesis]. University of Houston; 2014. [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/1454.
Council of Science Editors:
Wu T. DESIGN AND ANALYSIS OF THE ROTOR OF A FULLY SUPERCONDUCTING MACHINE. [Masters Thesis]. University of Houston; 2014. Available from: http://hdl.handle.net/10657/1454
University of Houston
6.
Sun, Yang.
Development of Carbon Nanofiber Reinforced HNBR Composite for Sealing Applications.
Degree: MS, Mechanical Engineering, University of Houston
URL: http://hdl.handle.net/10657/2814
► Carbon nanofiber(CNF) as a novel filler has been studied by researchers with huge enthusiasm owe to its special properties, like light weight, sustainability of large…
(more)
▼ Carbon nanofiber(CNF) as a novel filler has been studied by researchers with huge enthusiasm owe to its special properties, like light weight, sustainability of large deformation, chemical stability, corrosion and fatigue resistance, vibration and noise reduction capability, especially in rubber reinforcement. In this paper, cost effective carbon nanofibers (CNFs) are used as nanofillers in order to improve processing control and reproducibility for large scale engineering applications. Hydrogenated nitrile butadiene rubber (HNBR) is used as rubber matrix, for its outstanding performance in mechanical durability and chemical stability. Processing, microstructure, mechanical and thermal properties of HNBR have been studied along with nanofillers, CNFs and other conventional fillers, carbon black and silica. Mechanical measurements and microstructure analysis show that interfacial debonding happens in the hybrid-filler composites. The results indicated that the compatibility of CNF and conventional fillers is good and the modulus achieves highest at the cost of low elongation at certain ratio.
Advisors/Committee Members: Sun, Li (advisor), Bao, Jiming (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Carbon nanofibers; Nanocomposites; Nanostructures
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APA (6th Edition):
Sun, Y. (n.d.). Development of Carbon Nanofiber Reinforced HNBR Composite for Sealing Applications. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/2814
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Chicago Manual of Style (16th Edition):
Sun, Yang. “Development of Carbon Nanofiber Reinforced HNBR Composite for Sealing Applications.” Masters Thesis, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/2814.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
MLA Handbook (7th Edition):
Sun, Yang. “Development of Carbon Nanofiber Reinforced HNBR Composite for Sealing Applications.” Web. 19 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Vancouver:
Sun Y. Development of Carbon Nanofiber Reinforced HNBR Composite for Sealing Applications. [Internet] [Masters thesis]. University of Houston; [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/2814.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Council of Science Editors:
Sun Y. Development of Carbon Nanofiber Reinforced HNBR Composite for Sealing Applications. [Masters Thesis]. University of Houston; Available from: http://hdl.handle.net/10657/2814
Note: this citation may be lacking information needed for this citation format:
No year of publication.
University of Houston
7.
Sun, Sicong.
Synthesis and Characterization of Carbon Nanofiber Sheet Reinforced Polyvinyl Alcohol (PVA) Composite.
Degree: MS, Materials Engineering, University of Houston
URL: http://hdl.handle.net/10657/2816
► Carbon nanofibers (CNF) reinforced polymer composites with lightweight, sustainability of large deformation, oil and corrosion resistance can have positive impact on a wide range of…
(more)
▼ Carbon nanofibers (CNF) reinforced polymer composites with lightweight, sustainability of large deformation, oil and corrosion resistance can have positive impact on a wide range of applications. However, this type of composites is still under extensive research due to the difficulties in material handling and processes scale up. To improve processing control and reproducibility for large-scale engineering applications, cost effective carbon nanofibers (CNFs) in form of interconnected porous sheet (Buckypaper) were used as nano fillers. Microstructure of fiber sheet and composite, static mechanical and dynamic mechanical properties of CNF reinforced polyvinyl alcohol (PVA) have been investigated. The effect of dimethyl sulfoxide (DMSO) solvent has been compared to water and shows better improvement in wetting and forming covering layer on the carbon surface. Our sample fabrication technique forms a layered structure where the interfacial debonding between outside PVA layer and inner composite layer can lead to negative impact on static mechanical property. However, the static Mechanical measurements on the composite samples still show significant modulus enhancement that doubles that of pure PVA with the same fabrication process and condition. DMA and DSC measurements show that the unique sandwich-like composite samples have improved storage modulus changing Tg of PVA.
Advisors/Committee Members: Sun, Li (advisor), Song, Gangbing (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Carbon nanofibers; Polyvinyl alcohol (PVA)
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APA (6th Edition):
Sun, S. (n.d.). Synthesis and Characterization of Carbon Nanofiber Sheet Reinforced Polyvinyl Alcohol (PVA) Composite. (Masters Thesis). University of Houston. Retrieved from http://hdl.handle.net/10657/2816
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Chicago Manual of Style (16th Edition):
Sun, Sicong. “Synthesis and Characterization of Carbon Nanofiber Sheet Reinforced Polyvinyl Alcohol (PVA) Composite.” Masters Thesis, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/2816.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
MLA Handbook (7th Edition):
Sun, Sicong. “Synthesis and Characterization of Carbon Nanofiber Sheet Reinforced Polyvinyl Alcohol (PVA) Composite.” Web. 19 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Vancouver:
Sun S. Synthesis and Characterization of Carbon Nanofiber Sheet Reinforced Polyvinyl Alcohol (PVA) Composite. [Internet] [Masters thesis]. University of Houston; [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/2816.
Note: this citation may be lacking information needed for this citation format:
No year of publication.
Council of Science Editors:
Sun S. Synthesis and Characterization of Carbon Nanofiber Sheet Reinforced Polyvinyl Alcohol (PVA) Composite. [Masters Thesis]. University of Houston; Available from: http://hdl.handle.net/10657/2816
Note: this citation may be lacking information needed for this citation format:
No year of publication.
University of Houston
8.
-9810-4948.
Plasmonics Nanosensors for Improving the Sensitivity of Surface Enhanced Raman Spectroscopy.
Degree: PhD, Electrical Engineering, University of Houston
URL: http://hdl.handle.net/10657/3663
► Over the past four decades, the development of advanced techniques for fabricating metallic nanostructures has reinvigorated interest in using surface-enhanced Raman spectroscopy (SERS) for practical…
(more)
▼ Over the past four decades, the development of advanced techniques for fabricating metallic nanostructures has reinvigorated interest in using surface-enhanced Raman spectroscopy (SERS) for practical applications in molecular sensing and chemical compositional analysis. Although numerous SERS substrates have been reported, most lack the reproducibility, structural uniformity, high density of strong field regions-hot spots, large active area, and low cost required for applications. In this work, SERS substrates that address these issues are developed and characterized.
One of the earliest and simplest SERS substrate was evaporated Au/Ag nano-islands on glass substrates. However, the adhesion of these nano-islands is poor, particularly in aqueous environments. We showed that the use of sputter-deposition, instead of evaporation, provides reliable adhesion and, additionally, a practical way to control nucleation and film growth. By optimizing process conditions, we were able to induce nano-gaps in the films, which are known to be associated with a strong SERS response. In this work, through correlation between the process conditions, film morphology and SERS response, we have been able to obtain enhancement factors (EF) of 5 million, 5 times higher than the best evaporated films.
More recently, nanoporous gold (NPG), a bicontinuous 3-D porous gold structure formed by free corrosion of Au/Ag alloys, has generated considerable interest as a SERS substrate. NPG features a high density of hot spots and a tunable plasmon resonance. The structural evolution of NPG/Au bilayer films and its effects on SERS intensity were studied in detail. By optimizing pore structure, we were able to increase EF by a factor of 6 over the state-of-the-art; a 75-fold increase was achieved by optimizing the gold-layer thickness. Patterning the NPG film into sub-wavelength disk shaped structures (NPGDs) produces EFs as high as 500 million.
Finally, NPG and patterned gold sensors were formed on optical fiber substrates to explore plasmonics on optical fibers for remote sensing applications. In the first approach, NPG was deposited on fibers with cylindrical and tapered ends. In the second, periodic arrays of gold sensors were fabricated using ion beam proximity lithography, a high throughput approach where many fibers can be patterned simultaneously.
Advisors/Committee Members: Wolfe, John C. (advisor), Shih, Wei-Chuan (advisor), Wood, Lowell T. (committee member), Bao, Jiming (committee member), Yu, Cunjiang (committee member).
Subjects/Keywords: Plasmonics; Raman spectroscopy
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APA (6th Edition):
-9810-4948. (n.d.). Plasmonics Nanosensors for Improving the Sensitivity of Surface Enhanced Raman Spectroscopy. (Doctoral Dissertation). University of Houston. Retrieved from http://hdl.handle.net/10657/3663
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
No year of publication.
Chicago Manual of Style (16th Edition):
-9810-4948. “Plasmonics Nanosensors for Improving the Sensitivity of Surface Enhanced Raman Spectroscopy.” Doctoral Dissertation, University of Houston. Accessed January 19, 2021.
http://hdl.handle.net/10657/3663.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
No year of publication.
MLA Handbook (7th Edition):
-9810-4948. “Plasmonics Nanosensors for Improving the Sensitivity of Surface Enhanced Raman Spectroscopy.” Web. 19 Jan 2021.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
No year of publication.
Vancouver:
-9810-4948. Plasmonics Nanosensors for Improving the Sensitivity of Surface Enhanced Raman Spectroscopy. [Internet] [Doctoral dissertation]. University of Houston; [cited 2021 Jan 19].
Available from: http://hdl.handle.net/10657/3663.
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
No year of publication.
Council of Science Editors:
-9810-4948. Plasmonics Nanosensors for Improving the Sensitivity of Surface Enhanced Raman Spectroscopy. [Doctoral Dissertation]. University of Houston; Available from: http://hdl.handle.net/10657/3663
Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete
No year of publication.
. 
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