Abstract
In this study, high sensitivity UNCD (ultrananocrystalline diamond) micrielectrodes for real-time dopamine detection are investigated. It is believed that such a device could be used in the future for monitoring the change of dopamine concentration in Parkinson's disease and Alzheimer's Disease patients. High Pressure Liquid Chromatography (HPLC) has been widely used in hospitals due to its high sensitivity; however the expensive cost makes it inconvenient for general users. In order to improve this problem, a new dopamine sensor based on electrochemical detection is proposed. The dopamine sensor in this thesis includes N-doped UNCD interdigitated microelectrodes and CMOS (Complementary Metal Oxide Semiconductor) sensing circuit. First of all, by employing MEMS (Micro-Electro-Mechanical Systems) technology the sensor is fabricated on the silicon substrate coated with Si3N4. As the dopamine is detected by microelectrode, the sensor generates a current signal resulted from oxidation and reduction. Then, this current signal is converted to a voltage signal by the sensing circuit. Finally, the dopamine concentration can be calculated from the output data. Since the UNCD has flat surface, superior physical and chemical properties, it’s an excellent candidate material for microelectromechanical (MEMS) application. Its conductivity is close to that of an the insulator, so it has limited applications. By doping some elements to improve its conductivity, it can help the UNCD on the semiconductor and biomedical device applications.