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Articles 1 - 17 of 17

Full-Text Articles in Mechanical Engineering

Design And Synthesis Of Novel Nanometallic Catalysts And Electrode Materials For Green Fuel Cells, Jing Zhang May 2018

Design And Synthesis Of Novel Nanometallic Catalysts And Electrode Materials For Green Fuel Cells, Jing Zhang

Graduate Dissertations and Theses

The United Nations formally adopted 17 sustainable development goals (SDGs) at its 2015 summit. Many of these goals addressed issues such poverty, hunger, health, education, climate-change, gender equality, water, sanitation, energy, urbanization, environment and social justice. The seventh SDG seeks to ensure access to affordable, reliable, sustainable and modern energy for all. So among all renewable forms of energy, fuel cells with high efficiency have attracted a lot of attention recently. In particular, the direct ethanol fuel cells (DEFCs) and microbial fuel cells (MFCs) are significant due to their green fuel, less waste generated and environmental friendliness. Hence the overall ...


Highly Sensitive Biosensors With Interdigitated Electrode Arrays, Shaowei Ding Jan 2018

Highly Sensitive Biosensors With Interdigitated Electrode Arrays, Shaowei Ding

Graduate Theses and Dissertations

Electrochemical-based biosensors offer relative facile fabrication procedures, label free operation and rapid in field sensing and may hold a key to point-of-care diagnosis. Interdigitated electrodes (IDE) are often employed as the main sensing platform, and they consist of alternating ‘finger-like’ electrodes that are electrically connected with a width and pitch typically in the range of 5 – 25 m. Through the sensing modality of electrochemical impedance spectroscopy (EIS), it reveals small variations in resistance/capacitance due to the binding of biological recognition agents and biological targets. This dissertation documents the innovative research in electrochemical biomarker detection with interdigitated electrode arrays that ...


Highly Sensitive Biosensors With Interdigitated Electrode Arrays, Shaowei Ding Jan 2018

Highly Sensitive Biosensors With Interdigitated Electrode Arrays, Shaowei Ding

Graduate Theses and Dissertations

Electrochemical-based biosensors offer relative facile fabrication procedures, label free operation and rapid in field sensing and may hold a key to point-of-care diagnosis. Interdigitated electrodes (IDE) are often employed as the main sensing platform, and they consist of alternating ‘finger-like’ electrodes that are electrically connected with a width and pitch typically in the range of 5 – 25 m. Through the sensing modality of electrochemical impedance spectroscopy (EIS), it reveals small variations in resistance/capacitance due to the binding of biological recognition agents and biological targets. This dissertation documents the innovative research in electrochemical biomarker detection with interdigitated electrode arrays that ...


Fabrication Challenges And Perspectives On The Use Of Carbon-Electrode Dielectrophoresis In Sample Preparation, Rodrigo Martinez-Duarte Mar 2017

Fabrication Challenges And Perspectives On The Use Of Carbon-Electrode Dielectrophoresis In Sample Preparation, Rodrigo Martinez-Duarte

Publications

The focus of this review is to assess the current status of three-dimensional (3D) carbon-electrode dielectrophoresis (carbonDEP) and identify the challenges currently preventing it from its use in high-throughput applications such as sample preparation for diagnostics. The use of 3D electrodes over more traditional planar ones is emphasised here as a way to increase the throughput of DEP devices. Glass-like carbon electrodes are derived through the carbonisation of photoresist structures made using photolithography. These biocompatible carbon electrodes are not ideal electrical conductors but are more electrochemically stable than noble metals such as gold and platinum. They are also significantly less ...


Thermo-Mechanical Modeling And Parametric Analysis Of Lithium-Ion Battery, Abhishek Sarkar Jan 2017

Thermo-Mechanical Modeling And Parametric Analysis Of Lithium-Ion Battery, Abhishek Sarkar

Graduate Theses and Dissertations

Lithium-ion battery electrodes tend to fracture due to extensive mechanical stress and/or thermally fail by due to overheating. In our present research, we have studied the mechanical and thermal aspect of lithium battery electrodes. Two significant tasks were performed for this project. First, a numerical model was developed for analyzing the crack propagation during lithiation of crystalline silicon. We investigated the influence of mechanical properties of lithiated silicon on the fracture of silicon nanoparticles during lithiation. A chemo-mechanical model was used to determine the lithium distribution and associated stress states during lithiation. The concentration gradient of lithium and an ...


Synthesis, Characterization, And Electrochemical Properties Of Polyaniline Thin Films, Soukaina Rami Mar 2015

Synthesis, Characterization, And Electrochemical Properties Of Polyaniline Thin Films, Soukaina Rami

Graduate Theses and Dissertations

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of ...


Sr‐ And Ni‐Doped Lacoo3 And Lafeo3 Perovskites: New Cathode Materials For Solid‐Oxide Fuel Cells, Kevin Huang, Hee Y. Lee, John B. Goodenough Feb 2015

Sr‐ And Ni‐Doped Lacoo3 And Lafeo3 Perovskites: New Cathode Materials For Solid‐Oxide Fuel Cells, Kevin Huang, Hee Y. Lee, John B. Goodenough

Kevin Huang

An improved cathode material for a solid‐oxide fuel cell would be a mixed electronic and oxide‐ion conductor with a good catalytic activity for oxygen reduction at an operating temperature T op ≥ 700°C and a thermal expansion matched to that of the electrolyte and interconnect. We report on the properties of Sr‐ and Ni‐doped LaCoO3 and LaFeO3 perovskites that meet these criteria. Single‐phase regions were determined by X‐ray diffraction, and thermogravimetric analysis measurements were used to obtain the temperatures above which oxygen loss, and hence oxide‐ion conductivity, occurs. The conductivity and Seebeck ...


Liquid Cell Electron Microscopy With The Nanoaquarium: Radiation And Electrochemistry, Nicholas M. Schneider Jan 2015

Liquid Cell Electron Microscopy With The Nanoaquarium: Radiation And Electrochemistry, Nicholas M. Schneider

Publicly Accessible Penn Dissertations

The advent of the electron microscope has fostered major advances in a broad spectrum of disciplines. The required vacuum environment of standard electron microscopy, however, precludes imaging of systems containing high vapor pressure liquids. The recent development of liquid cells like the Penn nanoaquarium overcomes this limitation, enabling imaging of temporally evolving processes in liquids with nanoscale resolution at video frame rates. We used Liquid Cell Electron Microscopy to investigate the morphological evolution of the electrode-electrolyte interface during electroplating, the onset of diffusive instabilities in electrodeposits, beam-mediated nucleation, growth, and dissolution of metallic nanoparticles, the nucleation and growth of nanobubbles ...


Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya Dec 2013

Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya

Ömer Özgür Çapraz

No abstract provided.


Manufacturing Of Single Solid Oxide Fuel Cells, Jonathan Torres-Caceres Jan 2013

Manufacturing Of Single Solid Oxide Fuel Cells, Jonathan Torres-Caceres

Electronic Theses and Dissertations

Solid oxide fuel cells (SOFCs) are devices that convert chemical energy into electrical energy and have the potential to become a reliable renewable energy source that can be used on a large scale. SOFCs have 3 main components; the electrolyte, the anode, and the cathode. Typically, SOFCs work by reducing oxygen at the cathode into O2- ions which are then transported via the electrolyte to the anode to combine with a fuel such as hydrogen to produce electricity. Research into better materials and manufacturing methods is necessary to reduce costs and improve efficiency to make the technology commercially viable. The ...


Diffuse-Charge Dynamics Of Ionic Liquids In Electrochemical Systems, Hui Zhao Jan 2011

Diffuse-Charge Dynamics Of Ionic Liquids In Electrochemical Systems, Hui Zhao

Mechanical Engineering Faculty Publications

We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our simple scaling ...


Microbiosensors Based On Dna Modified Single-Walled Carbon Nanotube And Pt Black Nanocomposites, Jin Shi, Tae-Gon Cha, Jonathan C. Claussen, Alfred R. Diggs, Jong Hyun Choi, D. Marshall Porterfield Dec 2010

Microbiosensors Based On Dna Modified Single-Walled Carbon Nanotube And Pt Black Nanocomposites, Jin Shi, Tae-Gon Cha, Jonathan C. Claussen, Alfred R. Diggs, Jong Hyun Choi, D. Marshall Porterfield

Jonathan C. Claussen

Glucose and ATP biosensors have important applications in diagnostics and research. Biosensors based on conventional materials suffer from low sensitivity and low spatial resolution. Our previous work has shown that combining single-walled carbon nanotubes (SWCNTs) with Pt nanoparticles can significantly enhance the performance of electrochemical biosensors. The immobilization of SWCNTs on biosensors remains challenging due to the aqueous insolubility originating from van der Waals forces. In this study, we used single-stranded DNA (ssDNA) to modify SWCNTs to increase solubility in water. This allowed us to explore new schemes of combining ssDNA-SWCNT and Pt black in aqueous media systems. The result ...


Focussed Electric Field Induced Ion Transport: A Novel Nano-Patterning Process, Dibyadeep Paul Jan 2010

Focussed Electric Field Induced Ion Transport: A Novel Nano-Patterning Process, Dibyadeep Paul

Graduate Theses and Dissertations

FEFIIT is a unique method, which can be utilized to imprint complex structures on the surface of a conducting substrate. Experimental results have shown that under certain conditions, it is possible to obtain surface structures with characteristic length smaller than that of the mask. DC chopped simulations in particular yield unique features, which can be exploited to yield high aspect ratio structures. In this thesis, a model of this process is established and studied. Studies are conducted on the various length scale parameters as well as the starting concentration, and the potential applied. Two independent dimensionless parameters are found to ...


On The Nature Of The Electrochemically Synthesized Hard Fe-0.96 Mass Pct C Alloy Film Dec 2002

On The Nature Of The Electrochemically Synthesized Hard Fe-0.96 Mass Pct C Alloy Film

A.S. Md Abdul Haseeb

A hard Fe-0.96 mass pet C alloy with a hardness value of 810 HV has been electrochemically synthesized from a ferrous sulfate bath containing a small amount of citric acid and L-ascorbic acid. The nature of the alloy has been investigated by a number of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Mössbauer spectroscopy, differential scanning calorimetry (DSC), and magnetic measurements. The decomposition behavior of the alloy is also studied and compared with that of thermally prepared martensite. It has been found that the electrochemically deposited Fe-C alloy exists ...


On The Nature Of The Electrochemically Synthesized Hard Fe-0.96 Mass Pct C Alloy Film Nov 2002

On The Nature Of The Electrochemically Synthesized Hard Fe-0.96 Mass Pct C Alloy Film

A.S. Md Abdul Haseeb

A hard Fe-0.96 mass pet C alloy with a hardness value of 810 HV has been electrochemically synthesized from a ferrous sulfate bath containing a small amount of citric acid and L-ascorbic acid. The nature of the alloy has been investigated by a number of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Mössbauer spectroscopy, differential scanning calorimetry (DSC), and magnetic measurements. The decomposition behavior of the alloy is also studied and compared with that of thermally prepared martensite. It has been found that the electrochemically deposited Fe-C alloy exists ...


Fuel Cells, Frederick J. Munster Jr. Jan 1998

Fuel Cells, Frederick J. Munster Jr.

Maine Collection

Fuel Cells

by Frederick J. Munster Jr.

Edited by: Mr. Christopher Carroll

Maine Department of Economic Development, Augusta, Maine, 1998.

Contents: Hydrogen / Hydrogen Safety / Electrolysis / Electrolyzers / History of Fuel Cells / How Fuel Cells Operate / Fuel Cell Types / Fuel Cell Electrochemistry / Power Systems / Fuel Cells in Transportation / Hydrogen Powered Internal Combustion Engines / Home, Garden, Education and Industry / For More Information / Glossary / References


Sr‐ And Ni‐Doped Lacoo3 And Lafeo3 Perovskites: New Cathode Materials For Solid‐Oxide Fuel Cells, Kevin Huang, Hee Y. Lee, John B. Goodenough Jan 1998

Sr‐ And Ni‐Doped Lacoo3 And Lafeo3 Perovskites: New Cathode Materials For Solid‐Oxide Fuel Cells, Kevin Huang, Hee Y. Lee, John B. Goodenough

Faculty Publications

An improved cathode material for a solid‐oxide fuel cell would be a mixed electronic and oxide‐ion conductor with a good catalytic activity for oxygen reduction at an operating temperature T op ≥ 700°C and a thermal expansion matched to that of the electrolyte and interconnect. We report on the properties of Sr‐ and Ni‐doped LaCoO3 and LaFeO3 perovskites that meet these criteria. Single‐phase regions were determined by X‐ray diffraction, and thermogravimetric analysis measurements were used to obtain the temperatures above which oxygen loss, and hence oxide‐ion conductivity, occurs. The conductivity and Seebeck ...