Study of the sensitive properties of soluble dodecylsulfanyl phthalocyanines for organic vapors using impedance spectroscopy and QCR

A series of soluble dodecylsulfanyl phthalocyanines (DSPc) for the detection of organic vapors are investigated utilizing interdigital transducer electrode structures on a glass substrate and quartz crystal resonators. The sensing properties are studied by measuring changes in the transducer/coating composite properties upon exposure to the organic solvent vapor. The sensor parameters of interest are the electrostatic capacitance and the resistance of the composite collected by impedance methods, and the series- and parallel-resonant frequencies (f_s and f_p) of coated quartz-based oscillators. The results show that these multiple sensor parameters can be used to implement a multi-information sensor system. In addition, the interaction mechanism between the volatile organic molecules and the investigated phthalocyanine coatings are discussed utilizing the partition coefficients of the vapor molecules, and possible changes in electrical properties in the coatings.