Development of CMOS integrated electrochemical microsensors

Chlorine sensing is very important to maintain proper free chlorine concentration in water system. In this thesis, a CMOS integrated electrochemical microsensor based on cyclic voltammetry was developed, to provide inexpensive and effective on-site monitoring of free chlorine.;The current chlorine sensing technology has been reviewed. Simulation models and equivalent circuit models were used for studying the electrode/electrolyte solution system and cyclic voltammetry. A CMOS chip integrated with the three-electrode electrochemical cell and potentiostat circuit was designed and simulated. Post processing to generate the gold and silver/silver chloride electrodes on this CMOS chip was developed and performed. We have tested the on-chip op-amp after processing and analyzed the post processing performance by SEM and EDX spectroscopy.;Comprehensive study of the cyclic voltammetry for chlorine reduction was reported. Both large electrodes and microelectrodes with different sizes were applied for test and the obtained cyclic voltammograms were analyzed in detail. Numerical calculation and simulation of the voltammograms were performed. The relation between the chlorine concentration and the faradic current response was established. The obtained results confirmed that the CMOS integrated microsensors have the potential for applications in on-site chlorine monitoring in water systems.