CHARACTERIZATION OF MICROELECTRODE ARRAYS BY MEANS OF ELECTROCHEMICALAND SURFACE-ANALYSIS METHODS

Microelectrode arrays have been fabricated using silicon thin-film tec hnology. The arrays consist of 100 platinum microelectrodes connected in parallel to a single output line. In addition, a platinum counter e lectrode as well as a silver/silver chloride pseudo-reference electrod e are integrated on the microchip. We present results of surface analy sis of the microelectrode arrays by time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning electron microscopy (SEM) and scanni ng tunnelling microscopy (STM). The highly surface-sensitive analysis method SIMS reveals traces of Al and Ag impurities on the microelectro de surfaces. SEM micrographs show the embedding of the electrodes into insulating silicon oxide and silicon nitride layers. Furthermore, the y reveal an unexpected irregular, corrugated surface structure of the platinum electrodes, which are shown to be built up by small platinum grains. The microelectrode array is electrochemically characterized by means of cyclic and linear sweep voltammetry. The methods applied hav e successfully been used for the investigation and characterization of the surface structure and the composition of thin-film electrodes.