Carbon-based Electrodes in Neuroscience: Fundamental Electrochemistry and Nanoelectrode Development

For decades, carbon-fiber microelectrodes (CFMEs) have been a fundamental tool coupled with fast-scan cyclic voltammetry (FSCV) for real-time neurotransmitter detection. Although CFMEs have been widely used and have good electrochemical performance, the limitations cannot be ignored, including the lack of selectivity, poor fouling resistance, and size incompatible with synapse measurements. This dissertation aims to overcome the limitations of CFMEs by using various carbon-based electrodes and studying their electrochemical behaviors and aspects of sensing performance and mass transport near the electrode surface.
Chapter 1 describes the fundamental theories of FSCV, different types of electroactive neurotransmitters, surface properties of carbon nanomaterials, and techniques of nanofabrication. Chapters 2 and 3 introduce CNT yarn microelectrodes and the role of thin-layer electrochemistry in selectively detecting multiple neurotransmitters with FSCV, including cationic catecholamines and anionic neurochemicals. Chapter 4 explores the electrochemical performance of carbon nanospike (CNS) nanoelectrodes, which are fabricated by depositing CNSs on an etched metal wire. Chapter 5 introduces uniformly-coated, MPCVD-synthesized nanodiamond electrodes with excellent electrode fouling resistance. It then explores the electrochemical behavior after surface treatment with oxygen plasma in neurotransmitter detection. Chapter 6 addresses the development of a long, straight, and nano-sized needle with the novel 3D nano-printing technique and the optimization of the carbon electrode shape. Chapter 7 covers the challenges and future directions of electrochemical sensing performance using carbon nanomaterials and nanofabrication techniques.
Overall, this dissertation focuses on the surface chemistry of carbon nanomaterials and how it affects neurotransmitter sensing and addresses new methods to develop carbon-based electrodes for electrochemical sensing. This dissertation addresses how we overcome the limitations of CFMEs with FSCV, which may benefit the field of monitoring neurochemicals.