Characterization and functionalization of nanostructured indium tin oxide films

Abstract

We revise the ability of developing electrochemical biosensors made of indium tin oxide (ITO) through the fabrication, characterization and functionalization of nanostructured ITO electrodes. Self-made nanostructured ITO thin film and nanostructured electrodes were obtained by electron beam evaporation and the difference in morphology was confirmed by scanning electron microscopy (SEM). A high conductivity value ( 106 mS/cm) for self-fabricated and commercial samples was confirmed by the four points probe method. Cyclic voltammetry (CV) confirmed an increase in the electroactive surface area of ITO nanowires with respect to thin ITO films and commercial samples, implying possible higher detection levels. To study the detectability of nanostructured ITO surfaces, chemical functionalization was carried out. Fourier transform infrared spectroscopy (FTIR) confirmed that functionalization was correctly done and electrochemical impedance spectroscopy (EIS) showed that functionalized electrodes present higher polarization resistance, acting as an electronic barrier for the electron transfer between the ionic solution and the ITO electrode. These results are a first step to prove the benefits of sensing by using electrochemical biosensors, based on nanostructured ITO electrodes.