The main object of study of this dissertation is neurotransmitter release, a fundamental biological process implicated in memory and learning, emotions and behavior, as well as many other crucial cellular functions. Transmitter release is impaired in many diseases of the nervous system, including neurodegenerative diseases. Chapter 1 is an introduction to the mechanism of transmitter release by exocytosis and related biological concepts studied in the current work. The physicochemical techniques utilized to study exocytosis are introduced in Chapter 2. The roles of ?lamentous actin and nonmuscle myosin II in chromaf?n cell exocytosis as examined by ?uorescence microscopy, amperometry and cell-attached capacitance methods are analyzed in Chapter 3. Improved microfabricated electrochemical detector arrays, and their utilization in novel single cell measurements are demonstrated in Chapter 4. Chapter 5 describes random walk simulations and time domain deconvolution methods for modeling transmitter release and diffusion. Monitoring dopamine levels in the brain of freely moving research animals using a wired setup is presented in Chapter 6. Also in Chapter 6, the initial development of a wireless sensor for monitoring in vivo levels of dopamine is demonstrated.