Conductimetric sensor film

Keywords Langmuir-Blodgett film, pH sensors, conductimetric sensors, polypyrrole. 

X.F. Liu, F. Li, B. Yao, L. Wang, G.Y. Liu and C.Y Chai, Spectroscopic study of diazepam molecularly imprinted polymers and initiative application to conductimetric sensor based on molecularly imprinted films, Spectrosc. Spect. Anal, 30 (8) 2228-2231,2010. 

Capacitance-based chemical sensors are in the class of devices that transduce analytes into electrical currents. Such sensors are typically comprised of a dielectric, chemically-sensitive film coated onto a substrate electrode these films pass low conduction current, making amperometric or conductimetric measurements less sensitive or attractive for signal transduction. To detect an analyte, changes in the chemically-sensitive film s capacitive properties (associated with its dielectric constant, charge uptake, or formation of interface dipole layers) are measured when an active species is present or generated. 

Electrochemical sensor fabrication has dominated the analytical application of polymers. In some sensors the polymer film acts as a membrane for the preconcentration of ions or elements before electrochemical detection. Polymers also serve as materials for electrode modification that lower the potential for detecting analytes. In addition, some polymer films function as electrocatalytic surfaces. Using a polymer in biosensors is a very rapidly developing area of electroanalytical chemistry. Polymeric matrix modifiers have been applied as diffusional barriers in constructing not only sensitive amperometric biosensors, but also electrochemical sensors that apply potentiometric, conductimetric, optical, and gas-sensing transducer systems. The principles, operations, and application of potentiometric, conductimetric, optical and gas sensors are described in Refs. 13, 39-41. In this chapter, we focus mainly on amperometric biosensors based on redox enzymes. 

Here, we describe the construction and evaluation of a conductimetric pH sensor, based on a multilayer polypyrrole film [8]. The sensor is an interdigitated electrode array coated with the polymer by using the Langmuir-Blodgett (LB) technique [9]. Impedance spectroscopy has been used to investigate the complex admittance of the device when exposed to aqueous solutions of different pH. 

The IDA electrode coated with an electroconductive polymer also serves as a conductimetric pH-sensitive sensor device [75,109]. Measurements of free-standing dry polypyrrole films [110,111] showed that the conduc-... 

Gill E, Arshak A, Arshak K, Korostynska O (2010) Response mechanism of novel polyaniline composite conductimetric pH sensors and the effects of polymer binder, surfactant and film thickness on sensor sensitivity. Eur Polym J 46(10) 2042-2050, http //dx.doi.0rg/lO.lOl6/j. eurpolymj.2010.07.012... 

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