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- All Subjects: Glucose Sensors
- All Subjects: Materials Science
Description
Research concerning increased sensitivity and accurate glucose sensors have been on the forefront of diabetes mellitus. In this study, Electroactive Poly-Amidoamine Polymer (EPOP) was studied to determine if it can be used as a biocompatible electrode, with known redox mediators to determine if it can transfer its own electrons or amplify signal, and if signal is amplified when using an Ag/AgCl working electrode. From the results, it was determined that EPOP is neither a redox mediator, since it cannot transfer its own electrons, nor an electron mediator, since it does not amplify measured current at a specific voltage. Rather, it behaves as an electron sink capacitor with inconsistent behavior when Ag/AgCl is used as the working electrode with the redox mediator alone or with the redox mediator using in combination with glucose oxidase (GOx) and glucose. This was validated using AC-Impedance which gave a -3.3999 slope for isolated 0.05 g/mL EPOP in solution and R2 value of 0.992 displaying it had more capacitor-like behavior compared to resistor-like behavior. For this reason, EPOP was infused into a carbon screen-printed electrode by adding it dissolved and undissolved at two levels into carbon ink. The effectiveness of this electrode was tested using a potentiostatic CV. For the 0.1 g/mL EPOP dissolved in carbon ink, the reduction voltage peak (0.18 V) was found to be slightly higher than a GDE (0.14 V); however, the measured current was found to be 1.57 times the amplitude of a GDE. When 0.05 g/mL EPOP in PBS dissolved in graphite ink was used to detect glucose as the working electrode, there was increased signal amplification, and therefore, increased sensitivity to glucose when using EPOP infused electrodes. This offers promising results for disposable glucose sensors.
ContributorsKapadia, Meera Vipul (Author) / LaBelle, Jeffrey (Thesis director) / Islam, Rafiqul (Committee member) / Honikel, Mackenzie (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The story of graphene truly began in what was simply a stub in the journal Physical Review not two years after the end of World War II. In 1947, McGill University physicist P.R. Wallace authored “The Band Theory of Graphite” and attempted to develop a foundation on which the structure-property relationship of graphite could be explored; he calculates the number of free electrons and conductivity of what he describes as “a single hexagonal layer” and “suppos[es] that conduction takes place only in layers” in bulk graphite to predict wave functions, energies at specific atomic sites in the hexagonal lattice, and energy contours using a tight binding approximation for a hypothesized version of what we now call ‘armchair-style’ graphene. While Wallace was the first to explore the band structure and Brillouin Zones of single-layer graphite, the concept of two-dimensional materials was not new. In fact, for years, it was dismissed as a thermodynamic impossibility.
Everything seemed poised against any proposed physical and experimental stability of a structure like graphene. “Thermodynamically impossible”– a not uncommon shutdown to proposed novel physical or chemical concepts– was once used to describe the entire field of proposed two-dimensional crystals functioning separately from a three-dimensional base or crystalline structure. Rudolf Peierls and Lev Davoidovich Landau, both very accomplished physicists respectively known for the Manhattan Project and for developing a mathematical theory of helium superfluidity, rejected the possibility of isolated monolayer to few-layered crystal lattices. Their reasoning was that diverging thermodynamic-based crystal lattice fluctuations would render the material unstable regardless of controlled temperature. This logic is flawed, but not necessarily inaccurate– diamond, for instance, is thermodynamically metastable at room temperature and pressure in that there exists a slow (i.e. slow on the scale of millions of years) but continuous transformation to graphite. However, this logic was used to support an explanation of thermodynamic impossibility that was provided for graphene’s lack of isolation as late as 1979 by Cornell solid-state physicist Nathaniel David Mermin. These physicists’ claims had clear and consistent grounding in experimental data: as thin films become thinner, there exists a trend of a decreasing melting temperature and increasing instability that renders the films into islands at somewhere around ten to twenty atomic layers. This is driven by the thermodynamically-favorable minimization of surface energy.
Everything seemed poised against any proposed physical and experimental stability of a structure like graphene. “Thermodynamically impossible”– a not uncommon shutdown to proposed novel physical or chemical concepts– was once used to describe the entire field of proposed two-dimensional crystals functioning separately from a three-dimensional base or crystalline structure. Rudolf Peierls and Lev Davoidovich Landau, both very accomplished physicists respectively known for the Manhattan Project and for developing a mathematical theory of helium superfluidity, rejected the possibility of isolated monolayer to few-layered crystal lattices. Their reasoning was that diverging thermodynamic-based crystal lattice fluctuations would render the material unstable regardless of controlled temperature. This logic is flawed, but not necessarily inaccurate– diamond, for instance, is thermodynamically metastable at room temperature and pressure in that there exists a slow (i.e. slow on the scale of millions of years) but continuous transformation to graphite. However, this logic was used to support an explanation of thermodynamic impossibility that was provided for graphene’s lack of isolation as late as 1979 by Cornell solid-state physicist Nathaniel David Mermin. These physicists’ claims had clear and consistent grounding in experimental data: as thin films become thinner, there exists a trend of a decreasing melting temperature and increasing instability that renders the films into islands at somewhere around ten to twenty atomic layers. This is driven by the thermodynamically-favorable minimization of surface energy.
ContributorsShulman, Neal Arthur (Author) / Adams, James (Thesis director) / Islam, Rafiqul (Committee member) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05