Investigations of Printed Flexible pH Sensing Materials Based on Graphene Platelets and Submicron RuO2Powders

Abstract

The paper describes the investigations of pH-sensitive materials for screen printed flexible pH sensors. The sensors were fully printed and consisted of three layers, conductive made of low temperature-curable silver paste, insulating made of UV-curable dielectric paste, and pH-sensitive made of developed graphene/ruthenium oxide pastes. Graphene and ruthenium oxide composites were prepared with different proportions of graphene nanoplatelets paste and submicron ruthenium dioxide. To perform functional measurements, particular testing sensors were fabricated on flexible polyester foil. Afterwards electrochemical potential measurements of fabricated devices were carried out. Sensors were also exposed to cyclic bending and the change of pH sensitivity before and after bending was described. Eventually, percolation threshold concerning the amount of ruthenium oxide in the pH-sensitive layer was designated and UV influence on the sensitivity was observed that together allow for optimization of sensors’ fabrication costs.