Ruthenium dioxide quartz crystal nano-balance

A new type of quartz crystal nano-balance (QCN) has been designed using ruthenium oxide (RuO2) electrodes as substitutes for the metallic ones, which are generally used to prepare QCN sensors. The conductive RuO2 electrodes were deposited on quartz discs using reactive magnetron sputtering. XPS measurements showed the ratio of atomic concentrations [Ru]/[O] close to 1:2. XRD indicated crystalline structure of the deposits and AFM showed highly developed surface with pits and other features of various sizes. The oxide-based resonator operated stable in both gaseous and liquid environments as demonstrated by the prolonged experiments of water adsorption–absorption in humid air and electrochemical copper deposition–dissolution in acid solution. The sensor opens new opportunities to study thin films of RuO2. One of the advantages of the sensor is possibility to avoid the galvanic effects, which may occur when using the conventional QCN with metallic electrodes.