Miniaturized generator – collector electrochemical sensors

Electrochemical sensing is considered as one of the most powerful analytical detection techniques. Electrochemical methods have fast response time, high sensitivity and selectivity, and can be performed at low cost. Their inherent ease of miniaturization have made them so popular in recent years. Hence, electrochemical sensors have diverse applications including pathological, clinical, and environmental analyses. Miniaturization of analytical devices plays an important role in the sensor development studies. Miniaturized electrochemical sensors open up opportunities toward faster, more sensitive, more user friendly (ease to use) and portable systems compared to the traditional cumbersome bulky electrochemical cells. Thanks to the recent advances in nano/micro fabrication techniques, scaling down the electrode size to micro and even nano dimensions and developing “lab on a chip” technology is achievable and is considered as a hot topic in electrochemistry. Traditional electrochemical cells are composed of three electrodes: a working electrode, a reference electrode and a counter electrode. However, in this thesis the main focus is on the dual- electrode systems, where two closely spaced working electrodes are placed next to each other. Hence the events at each electrode can be affected by the other one. These two electrodes can be biased independently and the current of each can be detected separately. Biasing one of the electrodes in an oxidizing potential (according to a desired redox active analyte) and the other in a reducing potential, results in a repeated successive oxidation and reduction of analyte species on the two electrode surfaces. Accordingly, the current at each electrode is amplified which leads to a higher sensitivity. Reducing the gap size between the electrodes can further enhance the sensitivity and amplification factor (the ratio between the limiting current in dual electrode mode and the current in a single electrode mode) of the device.