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

Abstract

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 44 mV 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).