Customized Carbon Nanomaterials and MEMs Development for Neurochemical Detection

Carbon fiber microelectrodes (CFMEs), with fast-scan cyclic voltammetry (FSCV), are commonly used for the real-time tracking of neurotransmitters in vivo. CFs can detect multiple electroactive analytes, such as dopamine, but they are limited in the trapping of analytes and the prevention of fouling and biofouling. This dissertation aims to overcome the limitations of CFs by investigating different carbon-based electrode sensors, including the growth of carbon nanomaterials and graphitization of polymer via rapid thermal processor (RTP) and laser, and their applications for in vivo recording of neurochemicals. Chapter 1 covers the fundamental theories and recent developments of electrochemically neurochemical detection, nanofabrication methods, and laser-induced graphene with MEMs. Chapter 2 studies the surfaces of carbon nanospike-modified electrodes (CNSMEs). Rich surface defect sites and oxygen functional groups promote neurochemical adsorption and prevent fouling and biofouling. Chapter 3 explores the fabricated nanolayers of graphite from a commercial polymer, parylene. Induced graphite from parylene via rapid thermal processor (RTP) possesses good electrical conductivity and enables electrochemical detection of neurochemicals and in vivo tracking of dopamine and adenosine. Chapter 4 describes the method to graphitize parylene with the Nanoscribe laser, which is commonly used for the fabrication of 3D-printed structures. A single-channel Microelectromechanical systems (MEMs) chip was developed and combined with laser-induced graphene from parylene for dopamine detection. Finally, challenges and future directions using multiple-channel MEMs chips and nanofabrication techniques for electrode sensor fabrication are addressed in Chapter 5. Overall, my dissertation focuses on various fabrication methods of carbon sensors and MEMs development for neurotransmitter detection. The fundamental studies indicate that rich defect sites and oxygen functional groups benefit the prevention of fouling and biofouling. This work may benefit the further investigation of multiple-channel MEMs, with various electrode nanomaterials, for the co-detection of neurotransmitters.