Dissertation/Thesis Abstract

Highly Sensitive and Long Term Stable Electrochemical Microelectrodes for Implantable Glucose Monitoring Devices
by Qiang, Liangliang, Ph.D., University of Connecticut, 2012, 126; 3569982
Abstract (Summary)

A miniature wireless implantable electrochemical glucose system for continuous glucose monitoring with good selectivity, sensitivity, linearity and long term stability was developed. First, highly sensitive, long-term stable and reusable planar H2O2 microelectrodes have been fabricated by microlithography. These electrodes composed of a 300 nm Pt black layer situated on a 5 um thick Au layer, provide effective protection to the underlying chromium adhesion layer. Using repeated cyclic voltammetric sweeps in flowing buffer solution, highly sensitive Pt black working electrodes were realized with five-decade linear dynamic range and low detection limit (10 nM) for H2O2 at low oxidation potentials. Second, a highly sensitive, low cost and flexible microwire biosensor was described using 25-μm thick gold wire as working electrode together with 125-μm thick Pt/Ir and Ag wires as counter and reference electrode, embedded within a PDMS-filled polyethylene tube. Surface area and activity of sensor was enhanced by converting gold electrode to nanoporous configuration followed by electrodeposition of platinum black. Glucose oxidase based biosensors by electrodeposition of poly(o-phenylenediamine) and glucose oxidase on the working electrode, displayed a higher glucose sensitivity (1.2 mA mM-1 cm-2) than highest literature reported. In addition it exhibits wide detection range (up to 20 mM) and selectivity (>95%). Third, novel miniaturized and flexible microelectrode arrays with 8 of 25 μm electrodes displayed the much needed 3D diffusion profiles similar to a single 25 μm microelectrode, but with one order increase in current levels. These microelectrode arrays displayed a H2O2 sensitivity of 13 mA mM-1 cm-2, a wide dynamic range of 100 nM to 10 mM, limit of detection of 10 nM. These microwire based edge plane microsensors incorporated flexibility, miniaturization and low operation potential are an promising approach for continuous in vivo metabolic monitoring. Fourth, homemade miniature wireless potentisotat was fabricated based on low power consumption integrated circuits and surface mount parts. The miniature wireless potentisotat with up to two week life-time for continuous glucose sensing has a size less than 9×22×10 mm and weight ∼3.4 grams. Primary in vivo experiment showed homemade system has the exactly same respond and trend as commercial glucose meter.

Indexing (document details)
Advisor: Papadimitrakopoulos, Fotios
Commitee:
School: University of Connecticut
School Location: United States -- Connecticut
Source: DAI-B 74/09(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Biochemistry, Physical chemistry, Materials science
Keywords: Electrochemical microelectrodes, Glucose monitoring, Glucose sensors, Microfabrication, Wireless sensors
Publication Number: 3569982
ISBN: 978-1-303-08014-2
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