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Journal of Sensors
Volume 2017 (2017), Article ID 2190429, 6 pages
Research Article

Investigations of Printed Flexible pH Sensing Materials Based on Graphene Platelets and Submicron RuO2 Powders

1Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, A. Boboli 8, 02-525 Warsaw, Poland
2Institute of Biotechnology, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
3Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland

Correspondence should be addressed to Malgorzata Jakubowska

Received 5 December 2016; Revised 1 February 2017; Accepted 16 February 2017; Published 6 March 2017

Academic Editor: Sher Bahadar Khan

Copyright © 2017 Daniel Janczak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.