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 44 mV decade 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 to 10 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 and 10 to 10 M, respectively) and lower detection limits (10 and 10 M). The specificities of our perchlorate sensor have been tested for some interfering ions (nitrate, sulfate and carbonate).