Two types of systems: microelectrode array based analytical system for voltammetric monitoring of trace metals in natural waters and interdigitated electrodes system for electrochemiluminescence based analysis of codeine in pharmaceutical samples and for detection of ruthenium (II) complex label is described in the paper. The thin-film technology was used for microfabrication of an array of 100 interconnected Ir microdisc electrodes on Si/ShN4 substrate. The electrochemiluminescence system combines electrodes, a flowthrough cell and a photodetector on the same silicon chip.