Print-Light-Synthesis of ruthenium oxide thin film electrodes for electrochemical sensing applications

Print-Light-Synthesis (PLS) combines the inkjet printing of a ruthenium precursor ink with the simultaneous photo-induced generation of ruthenium oxide films. During PLS, inkjet-printing generates on conductive as well as insulating substrates micrometer-thin reaction volumes that contain with high precision defined precursor loadings. Upon direct UV light irradiation, the Ru precursor converts to RuO 2 while all other ink components escape in the gas phase. No post PLS processes are required, and the as-obtained RuO 2 films can be immediately used as electrochemical devices. Two-dimensional RuO 2 patterns with micrometric resolution and highlycontrolled ruthenium loadings (few µg/cm 2) are realized. Thin RuO 2 films are generated on insulating substrates, such as polyimide, as well as individual RuO 2 particles on conductive substrates, such as graphene layers. The RuO 2 films are characterized by electron microscopy and spectroscopic techniques. The sensoristic applicability of the PLS-RuO 2 electrodes is demonstrated by potentiometric pH sensing in cell cultures and amperometric detection of L-cysteine. For pH sensing the RuO 2 film electrodes show Nernstian sensitivity. L-cysteine detection of RuO 2-modified graphene electrodes showed an electrocatalytical effect and resulted in the possibility of selectively detecting L-Cysteine also in presence of the interfering compound uric acid. ☆ This article is part of a special issue entitled: '11th SMCBS 2023 Workshop' published in Bioelectrochemistry.