Electrochemical sensors basic potentiometric sensor

Scheme of a basic potentiometric sensor electrodes and electrolyte (a) with reference atmosphere chamber and (b) without reference.The electrochemical U potential is measured between electrodes. 

Schematic diagram of an enzymatically coupled potentiometric sensor is shown in Fig.6. Its basic operating principle is simple an enzyme (a catalyst) is immobilized inside a layer into which the substrate(s) diffuse. As it does it reacts according to the Michaelis-Menten mechanism and the product(s) diffuse out of the layer, into the solution. Any other species which participate in the reaction must also diffuse in and out of the layer. Because of the combined mass transport and chemical reaction this problem is often referred to as diffusion-reaction mechanism. It is quite common in electrochemical reactions where the electroactive...

Focused on the electrochemical applications used to design sensors for ionic, molecular or gas species. Targeted at BA level and master s degree students, as well as students at engineering school, it is also adapted to selftraining. This book provides a recap of the basic concepts, before then applying them to different types of transduction (amperometric, conductimetric and potentiometric sensors). There is also a selection of problems to solve with the corrections provided. 

Smiechowski and Lvovich monitored the levels of acidity and basicity in industrial lubricant. The sensor was based on electrochemical impedance methodology. An iridium oxide potentiometric sensor was developed in both a conventional and MEMS configuration. Tests of the sensors in diesel lubricant showed good correlation between TAN, TEN, and the voltage output of each sensor [7]. Widera et al. used a potentiometric iridium oxide electrode as an indicating electrode with a silver/silver chloride reference electrode for the off-line monitoring of fuel acidity. The data showed that the iridium oxide sensor responds to compounds present in fuel that have acid-base character and it is possible to determine the acidity of different fuels and discriminate between unstressed and thermally stressed fuels. Experimental results indicated the ability to correlate the response of the iridium oxide sensor with the total acid numbers of different fuels [20]. 

In Chapters 6 and 7, we discussed potentiometric and amperometric sensors, respectively. The third basic electrochemical parameter that can yield sensory information is the conductance of the electrochemical cell (Fig. 8.1). Conductance is the reciprocal of resistance. It is related to current and potential through the generalized form of Ohm s law (C.l). If the measurement is done with AC signal conductance (G) becomes frequency-dependent conductance G(co) and the resistance R becomes impedance Z( (o). 

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