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Full-Text Articles in Mechanical Engineering
Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John H. Harb, Jonathan C. Claussen, Brian D. Iverson
Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John H. Harb, Jonathan C. Claussen, Brian D. Iverson
Faculty Publications
Free-standing, vertically aligned carbon nanotubes (VACNTs) were patterned into 16 μm diameter microchannel arrays for flow-through electrochemical glucose sensing. Non-enzymatic sensing of glucose was achieved by the chemical reaction of glucose with methyl viologen (MV) at an elevated temperature and pH (0.1 M NaOH), followed by the electrochemical reaction of reduced-MV with the VACNT surface. The MV sensor required no functionalization (including no metal) and was able to produce on average 3.4 electrons per glucose molecule. The current density of the MV sensor was linear with both flow rate and glucose concentration. Challenges with interference chemicals were mitigated by operating …
Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John N. Harb, Jonathan C. Claussen, Brian D. Iverson
Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John N. Harb, Jonathan C. Claussen, Brian D. Iverson
Faculty Publications
Freestanding, vertically aligned carbon nanotubes (VACNTs) were patterned into 16 μm diameter microchannel arrays for flow-through electrochemical glucose sensing. Non-enzymatic sensing of glucose was achieved by the chemical reaction of glucose with methyl viologen (MV) at an elevated temperature and pH (0.1 M NaOH), followed by the electrochemical reaction of reduced-MV with the VACNT surface. The MV sensor required no functionalization (including no metal) and was able to produce on average 3.4 electrons per glucose molecule. The current density of the MV sensor was linear with both flow rate and glucose concentration. Challenges with interference chemicals were mitigated by operating …
Bubble Nucleation In Superhydrophobic Microchannels Due To Subcritical Heating, Adam Cowley, Daniel Maynes, Julie Crockett, Brian D. Iverson
Bubble Nucleation In Superhydrophobic Microchannels Due To Subcritical Heating, Adam Cowley, Daniel Maynes, Julie Crockett, Brian D. Iverson
Faculty Publications
This work experimentally studies the effects of single wall heating on laminar flow in a high-aspect ratio superhydrophobic microchannel. When water that is saturated with air is used as the working liquid, the non-wetted cavities on the superhydrophobic surfaces act as nucleation sites and allow air to effervesce out of the water and onto the surface when heated. Previous works in the literature have only considered the opposite case where the water is undersaturated and absorbs air out the cavities for a microchannel setting. The microchannel considered in this work consists of a rib/cavity structured superhydrophobic surface and a glass …
Hydrodynamic And Thermal Effects Of Sub-Critical Heating On Superhydrophobic Surfaces And Microchannels, Adam M. Cowley
Hydrodynamic And Thermal Effects Of Sub-Critical Heating On Superhydrophobic Surfaces And Microchannels, Adam M. Cowley
Theses and Dissertations
This dissertation focuses on the effects of heating on superhydrophobic (SHPo) surfaces. The work is divided into two main categories: heat transfer without mass transfer and heat transfer in conjunction with mass transfer. Numerical methods are used to explore the prior while experimental methods are utilized for the latter. The numerical work explores convective heat transfer in SHPo parallel plate microchannels and is separated into two stand-alone chapters that have been published archivally. The first considers surfaces with a rib/cavity structure and the second considers surfaces patterned with a square lattice of square posts. Laminar, fully developed, steady flow with …
Transport Enhancement Of Rate-Limited Chemical Reactions Via Pt-Decorated, Carbon Nanotube Microarray Membranes, Kevin M. Marr
Transport Enhancement Of Rate-Limited Chemical Reactions Via Pt-Decorated, Carbon Nanotube Microarray Membranes, Kevin M. Marr
Theses and Dissertations
Rate limited chemical reactions can be enhanced by improving the mass transport of the suspended analyte to the catalytic (or electrocatalytic) surface. While many attempts have been made to enhance this mass transport, these approaches are limited to utilizing only two enhancement methods – increasing available catalytic surface area, and increasing the flow of analyte in solution. Flow through high aspect ratio microstructures, however, would provide additional mass transport enhancement via boundary layer confinement. Platinum functionalized carbon nanotube microarray membranes (Pt-CNT-MMs) offer enhanced mass transport via all three methods, and were fabricated for demonstration in a H2O2 sample system, for …
High Aspect Ratio, Carbon Nanotube Membranes Decorated With Pt Nanoparticle Urchins For Micro Underwater Vehicle Propulsion Via H2O2 Decomposition, Kevin M. Marr, Bolin Chen, Eric J. Mootz, Jason Geder, Marius Pruessner, Brian J. Melde, Richard R. Vanfleet, Igor L. Medintz, Brian D. Iverson, Jonathan C. Claussen
High Aspect Ratio, Carbon Nanotube Membranes Decorated With Pt Nanoparticle Urchins For Micro Underwater Vehicle Propulsion Via H2O2 Decomposition, Kevin M. Marr, Bolin Chen, Eric J. Mootz, Jason Geder, Marius Pruessner, Brian J. Melde, Richard R. Vanfleet, Igor L. Medintz, Brian D. Iverson, Jonathan C. Claussen
Faculty Publications
The utility of unmanned Micro Underwater Vehicles (MUVs) is paramount for exploring confined spaces, but their spatial agility is often impaired when maneuvers require burst-propulsion. herein we develop high-aspect ratio (150:1), multi-walled carbon nanotube microarray membranes (CNT-MMs) for propulsive, MUV thrust generation by the decomposition of hydrogen peroxide (H2O2). The CNT-MMs are grown via chemical vapor deposition with diamond shaped pores (nominal diagonal dimensions of 4.5 × 9.0 [µm]) and subsequently decorated with urchin-like, platinum (Pt) nanoparticles via a facile, electroless, chemical deposition process. The Pt-CNT-MMs display robust, high catalytic ability with an effective activation energy …
Capillary Filling Of Large Aspect Ratio Channels With Varying Wall Spacing, Dallin B. Murray
Capillary Filling Of Large Aspect Ratio Channels With Varying Wall Spacing, Dallin B. Murray
Theses and Dissertations
Quantification and prediction of capillary fluid flow in planar nanochannels is essential to the development of many emerging nanofluidic technologies. Planar nanochannels are typically produced using the standard nanofabrication processes of thermal bonding or sacrificial etching. Both approaches may yield nanochannels that are bowed and/or exhibit non-uniform (i.e. non-planar) wall spacing. These variations in wall spacing affect the transient dynamics of a liquid plug filling the nanochannel, causing deviations from the classical behavior in a parallel-plate channel as described by the Washburn model. Non uniform wall spacing impacts the overall frictional resistance and influences the meniscus curvature. In this thesis, …
Numerical Study Of Fully Developed Laminar And Turbulent Flow Through Microchannels With Longitudinal Microstructures, Kevin B. Jeffs
Numerical Study Of Fully Developed Laminar And Turbulent Flow Through Microchannels With Longitudinal Microstructures, Kevin B. Jeffs
Theses and Dissertations
Due to the increase of application in a number of emerging technologies, a growing amount of research has focused on the reduction of drag in microfluidic transport. A novel approach reported in the recent literature is to fabricate micro-ribs and cavities in the channel wall that are then treated with a hydrophobic coating. Such surfaces have been termed super- or ultrahydrophobic and the contact area between the flowing liquid and the solid wall is greatly reduced. Further, due to the scale of the micropatterned structures, the liquid is unable to wet the cavity and a liquid meniscus is formed between …
Design And Fabrication Of Out-Of-Plane Silicon Microneedles With Integrated Hydrophobic Microchannels, Michael S. Diehl
Design And Fabrication Of Out-Of-Plane Silicon Microneedles With Integrated Hydrophobic Microchannels, Michael S. Diehl
Theses and Dissertations
Microfabricated needles have the potential for inexpensive drug delivery without pain. The ability to deliver medication painlessly to patients will someday be not just hoped for but expected by the general public. The commercialization of this technology will also lead to other valuable technologies, such as systems that continually monitor and control insulin or other drugs in diabetic patients. This research presents fabrication procedures developed to produce pyramidal-shaped microneedles with microchannels that will allow for fluid delivery. The microchannels are etched into the substrate surface of a [100] silicon wafer using inductively coupled plasma etching. After the channel etch a …
Thermally Developing Electro-Osmotic Convection In Circular Microchannels, Spencer L. Broderick
Thermally Developing Electro-Osmotic Convection In Circular Microchannels, Spencer L. Broderick
Theses and Dissertations
Thermally developing, electro-osmotically generated flow has been analyzed for a circular microtube under imposed constant wall temperature (CWT) and constant wall heat flux (CHF) boundary conditions. Established by a voltage potential gradient along the length of the microtube, the hydrodynamics of such a flow dictate either a slug flow velocity profile (under conditions of large tube radius-to-Debye length ratio, a/lambda_d) or a family of electro-osmotic flow (EOF) velocity profiles that depend on a/lambda_d. The imposed voltage gradient results in Joule heating in the fluid with an associated volumetric source of energy. For this scenario coupled with a slug flow velocity …