Date of Graduation

8-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry (PhD)

Degree Level

Graduate

Department

Chemistry & Biochemistry

Advisor/Mentor

Fritsch, Ingrid

Committee Member

Stenken, Julie A.

Second Committee Member

Beitle, Robert R. Jr.

Third Committee Member

Wilkins, Charles L.

Fourth Committee Member

Kaman, Tulin

Keywords

3D and 2D computer simulations; double layer charging; electron-conducting material; heterogeneous electron transfer kinetics; microband electrode arrays; redox cycling

Abstract

The numerical studies in this dissertation explore the application of redox cycling, an advanced electrochemical technique, for analyzing bioelectrochemical systems with a particular focus on small-volume samples and involves electrodes that can be activated to oxidize and reduce, separated by varying distances and featuring different geometries. The redox cycling approach facilitates the spatio-temporal interrogation of kinetics, mass transport, and the quantification and identification of chemical systems. We optimize a previously fabricated neural probe design on an SU-8 substrate, featuring coplanar arrays of nine microband electrodes suited for in vivo applications. Through comprehensive in situ and in silico redox cycling studies and confining the electroactive footprint to 70 µm×100 µm, we examine various arrays of microband electrode arrays to gain a better understanding of their spatially and temporally resolved current responses. This research advances the optimization of electrode arrays, significantly enhancing electrochemical detection through redox cycling. Our findings contribute to the fundamental understanding of theory of single microband electrode and arrays of microbands, paving the way for developing advanced miniaturized medical devices for ultrasmall volume of chemical systems and in vivo investigations of neurological functions and related diseases. Additionally, we propose mathematical models demonstrating that the suitability of electrochemical methods for quantitative measurements at these microdevices is influenced by the relatively large electrode-insulator interface-to-electrode area ratio, which significantly impacts charging dynamics due to interactions among electrolyte, conductor material, and insulator layers. We benchmark prior publications on alternative conductor-insulator materials against our study, revealing that devices constructed with SU-8 exhibit more favorable electrochemical performance compared to those made with glass, epoxy, silicon nitride, and, under certain conditions, polyimide.

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