Development of a capacitive chemical sensor based on Co(II)-phthalocyanine acrylate-polymer/HfO2/SiO2/Si for detection of perchlorate.

We report the development of a chemical sensor based on a Co(II) phthalocyanine acrylate polymer (Co(II)Pc-AP) for perchlorate anion detection. We have used two types of transducers, silicon nitride (Si₃N₄/ and hafnium oxide (HfO₂/. The adhesion of the Co(II)Pc-AP on different transducers and their surface qualities have been studied by contact angle measurements. We have studied the pH effect on Al/Si/SiO₂/HfO₂/electrolyte capacitance values for different phosphate buffer solutions (PBS). This optimization step has allowed a sensitivity value of about 44mV decade^-1 towards H⁺ ions. The fabricated sensors based on Si₃N₄ and HfO₂ transducers functionalized with a Co(II)Pc-AP membrane have been characterized by C(V) measurements for different perchlorate concentrations (from 10^-7 to 10^-2 M). The sensor developed with the HfO₂ transducer shows better performances compared to that based on Si₃N₄: a larger detection range (10^-7 to 10^-2 and 10^-3 to 10^-2 M, respectively) and lower detection limits (10^-7 and 10^-3 M). The specificities of our perchlorate sensor have been tested for some interfering ions (nitrate, sulfate and carbonate). [ABSTRACT FROM AUTHOR]