Transparent and flexible carbon nanotube/polypyrrole and carbon nanotube/polyaniline pH sensors

Thin film Carbon Nanotube (CNT) networks are used as a conductive, transparent and flexible electrode for electrochemically depositing a conducting polymer on it, polypyrrole or polyaniline in the present work. We analyse the properties of the device as an electrochemical sensor, measuring his pH dependence by recording the open circuit potential in various buffer solutions, ranging from pH 1 to 13. The results show a good sensitivity, linearity and stability in both cases. In the case of CNT/polyaniline, it can be used simply as an optical sensor, as the colour of polyaniline changes with pH. The CNT/polypyrrole and CNT/polyaniline devices could have applications as solid state gas sensor or biosensor deposited on any shape of surface that can be transparent and flexible. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)