Electroanalytical sensors

Electrochemical sensors play a crucial role in environmental and industrial monitoring, as well as in medical and clinical analysis. The common feature of all electroanalytical sensors is that they rely on the detection of an electrical property (i.e., potential, resistance, current) so that they are normally classified according to the mode of measurement (i.e., potentiometric, conductometric, amperometric). A number of surveys have been published on this immense field. The reader may find the major part of the older and recent bibliography in the comprehensive reviews of Bakker et al. [109-111]. Pejcic and De Marco have presented an interesting survey... 

Electroanalytical sensors based on amperometric measurements at chemically modified electrodes are in the early stages of development. The modes of modification can take many forms, but the most common approach at the present time is the immobilization of ions and molecules in polymer films which are applied to bare metal, semiconductor, and carbon electrodes. Such surface-modified electrodes exhibit unique electrochemical behavior which has been exploited for a variety of applications. 

One of the major deterrents to the successful application of electroanalytical sensors has been the lack of long-term stability of the polymer films. At least three factors effect the stability of these amperometric sensors. These factors are the mode of polymer film attachment to the electrode surface (adsorption vs. covalent bonding), solubility of the film in the contacting solution, and finally, the mode of attachment of the catalyst in the polymer film (electrostatic vs. covalent). 

E. Pungor, Z. Feher, G. Nagy, K. Toth, G. Horvai, M. Gratzl, Injection techniques in dynamic flow-through analysis with electroanalytical sensors, Anal. Chim. Acta 109 (1979) 1. 

Although there is no doubt that surface science is a discipline on its own, in practically oriented electroanalytical chemistry it is mostly an auxiliary force to establish the mechanism of electrode signal. A recent, rapid development of electroanalytical sensors provided the evidence that to get more incisive knowledge of surface-located signal forming processes it is necessary to set a new or to improve existing analytical procedures. Therefore the inspection of surface processes by suitable methods seems to be an indispensable feature of electroanalytical chemistry of today. 

Metters, J.P., Kadara, R.O., and Banks, C.E. (2011) New directions in screen printed electroanalytical sensors an overview of recent developments. Analyst, 136, 1067-1076. 

The performance of electroanalytical sensors is strictly related to size and shape of the nanosized material employed. This means that, in order to define reliable property-structure relationships, the nano-objects must possess a similar shape and narrow size distribution, i.e., characterized by a relative standard deviation of less than 20 %. Many parameters that depend on the synthetic procedure adopted affect the size, size distribution, and shape of the resulting nano-objects. 

Bontempelli G, Comisso N, Toniolo R, Schiavon G (1997) Electroanalytical sensors for nonconducting media based on electrodes supported on perfluoiinated ion-exchange membranes. Electroanalysis 9 433-443 Cao Z, Stetter JR (1991) Amperometiic gas sensors. In Madou M, Joseph JP (eds) Opportunities for innovation chemical and biological sensors. NIST Publication GCR 91-593-1, U.S. Department of Commerce, Gaithersburg, MD Cao Z, Buttner WJ, Stetter JR (1992) The properties and applications of amperometric gas sensors. Electroanalysis 4 253-266... 

An ionometric system for the analysis of electrolyte solutions has been developed Planar chip structures of ion sensitive field effect tansistors (ISFET s) and ion selective electrodes (ISE s) are used as sensors Their layout allows an easy preparation of the ion sensitive membrane and also a very simple electrical contacting The sensor chips can be clipped to small volume flow-through cells for dynamic measurements An advanced electronic device was developed for measuring both, the ISFET and the ISE signals This system is usefial for basic investigations of ion sensitive materials and can be integrated comfortably into electroanalytical sensor/actuator microsystems... 

Power, A.C. and Morrin, A. (2013) Electroanalytical sensor technology, in Electrochemistry (ed. MAA. Khalid), InTech. 

As discussed later in this subchapter and in several chapters of this book, direct analytical measurement of metal species is probably the most relevant feature of electroanalytical sensors with respect to other available analytical techniques for... 

The Phoenix Wet Chemistry Laboratory (WCL) Electroanalytical Sensor Array... 

Automated wet chemical analysis systems such as CHEMSENS and NERNST can be used in conjunction with electroanalytical sensors, not only to reduce the mass, cost, and power consumption of the instrument, but also to provide a very detail picture of the aqueous geochemistry of samples in remote extreme environments. The direction of such devices points to evermore sophisticated robotic systems that could one day provide basically the same chemical analyses as a sophisticated terrestrial anal3Tical laboratory. 

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