Silicon Nitride Capacitive Chemical Sensor for Phosphate Ion Detection Based on Copper Phthalocyanine – Acrylate-polymer

© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim In this work, we report the development of a highly sensitive capacitance chemical sensor based on a copper C,C,C,C-tetra-carboxylic phthalocyanine-acrylate polymer adduct (Cu(II)TCPc-PAA) for phosphate ions detection. A capacitance silicon nitride substrate based Al−Cu/Si-p/SiO2/Si3N4 structure was used as transducer. These materials have provided good stability of electrochemical measurements. The functionalized silicon-based transducers with a Cu(II)Pc-PAA membrane were characterized by using Mott-Schottky technique measurements at different frequency ranges and for different phosphate concentrations. The morphological surface of the Cu(II)Pc-PAA modified silicon-nitride based transducer was characterized by contact angle measurements and atomic force microscopy. The pH effect was also investigated by the Mott-Schottcky technique for different Tris-HCl buffer solutions. The sensitivity of silicon nitride was studied at different pH of Tris-HCl buffer solutions. This pH test has provided a sensitivity value of 51 mV/decade. The developed chemical sensor showed a good performance for phosphate ions detection within the range of 10−10 to 10−5 M with a Nernstian sensitivity of 27.7 mV/decade. The limit of detection of phosphate ions was determined at 1 nM. This chemical sensor was highly specific for phosphate ions when compared to other interfering ions as chloride, sulfate, carbonate and perchlorate. The present capacitive chemical sensor is thus very promising for sensitive and rapid detection of phosphate in environmental applications.