New Microfabricated Tools for Electrochemical Imaging and Sensing

Abstract

This dissertation covers the development of microfabricated bipolar ultramicroelectrode arrays consisting of many thousands of individually addressable electrodes to enable high resolution electrochemical imaging. Two different devices are presented and discussed prior to characterization in several proof-of-concept experiments, after which one of the array designs is utilized in the creation of a high-throughput electrocatalyst screening platform. Additionally, a micromachining procedure for the fabrication of glass-supported solid-state nanopore substrates is introduced. Chapter 1 opens with an introduction to various electrochemical imaging techniques and examines bipolar coupling to an optical reporter reaction as a method for simultaneously reading the current through very dense electrode arrays. The advantages of such a scheme are further explored from the perspective of efficient electrocatalytic screening before the chapter concludes with a discussion of possible solutions to the issues associated with high frequency biomolecule detection via resistive pulse sensing in solid-state nanopores. Chapter 2 then presents a submicron bipolar microelectrode array design which utilizes interfering laser beams to generate the requisite periodic electrode patterns. The shortcomings of this design are addressed in Chapter 3 with the fabrication of an updated device which is used to image several dynamic electrochemical systems via an alternate imaging scheme. This updated device is further utilized in Chapter 4 as a platform for highly parallelized screening of compositionally varied electrocatalyst samples. Chapter 5 then closes this dissertation with the introduction of a novel microfabrication method for freestanding SiNx membranes on glass chips as a means of eliminating the capacitive noise effects associated with semiconductor/insulator interfaces in high bandwidth solid-state nanopore measurements.