Electrochemical sensor cell

Logothetis, E. M., Visser, J. H., Soltis, R. E. and Rimai, L. (1992), Chemical and physical sensors based on oxygen pumping with solid-state electrochemical cells. Sensors and Actuators B, 9,183-9. 

Many physical principles can be employed by different sensor vendors to obtain the same measurement. For example, in 1995, 49 vendors were listed for hydrogen sensing (2). Represented among the sensor systems are mass spectrometers, gas chromatographs, electrochemical cells, thermal... 

Carbon monoxide and carbon dioxide can be measured using the FTIR techniques (Fourier transform infrared techniques see the later section on the Fourier transform infrared analyzer). Electrochemical cells have also been used to measure CO, and miniaturized optical sensors are available for CO 2 monitoring. 

A problem common to electrochemical cells is the analyzer can fail (degradation of the anode material and electrolyte or loss of sensor sensitivity), but still indicate a safe oxidant level when in reality it may not be so. Adherence to the manufacturer s recommendation as to how... 

Microfabrication technology has made a considerable impact on the miniaturization of electrochemical sensors and systems. Such technology allows replacement of traditional bulky electrodes and beaker-type cells with mass-producible, easy-to-use sensor strips. These strips can be considered as disposable electrochemical cells onto which the sample droplet is placed. The development of microfabricated electrochemical systems has the potential to revolutionize the field of electroanaly-tical chemistry. 

Brovkovych et al. [38] applied the electrochemical porphyrinic sensor technique for the direct measurement of NO concentrations in the single endothelial cell. It was found that NO concentration was the highest at the cell membrane (about 1 pmoll-1) and decreased exponentially with distance from the cell, becoming undetectable at the distance of 50 pm. Now we will consider the principal reactions of nitric oxide relevant to real biological systems. 

Electrochemical cells where ions dissipate through a solid electrolyte are mainly used for measuring oxygen concentrations. The most common sensors based on this principle are the A-probe for monitoring combustion engines in motor vehi-... 

Suitable methods for CO indoor monitoring are based on using metal oxide sensors (chapter 5.3.2.1), electrochemical cells (chapters 5.3.2.3 and 5.3.2.4), pellis-tors (chapter 53.2.2) and optical methods (chapter 5.3.2.5). An overview of CO-sensors and systems is given in Tab. 5.9. 

With the introduction of modern electronics, inexpensive computers, and new materials there is a resurgence of voltammetric techniques in various branches of science as evident in hundreds of new publications. Now, voltammetry can be performed with a nano-electrode for the detection of single molecular events [1], similar electrodes can be used to monitor the activity of neurotransmitter in a single living cell in subnanoliter volume electrochemical cell [2], measurement of fast electron transfer kinetics, trace metal analysis, etc. Voltammetric sensors are now commonplace in gas sensors (home CO sensor), biomedical sensors (blood glucose meter), and detectors for liquid chromatography. Voltammetric sensors appear to be an ideal candidate for miniaturization and mass production. This is evident in the development of lab-on-chip... 

Electrochemical cells are of two types power cells and sensors. In an ideal power cell, the ionic current through the electrolyte inside the cell matches an electronic current through an external load. The solid electrolyte is in the form of a membrane of thickness L and area A that separates electronically the two electrodes of the cell. Any internal electronic current across the electrolyte reduces the power output. The internal resistance to the ionic current is... 

The gas phase detection of iodine vapor with an electrochemical probe has been investigated [195]. The Ag AgI Au electrochemical cell was observed to be sensitive to interference from both oxygen and humidity. A sensor based on a Ag Ag(Cs)I graphite electrode system has been reported by Sola etal. [196]. Temperature effects were studied and the effect of Csl doping of the Agl explored to widen the working temperature range. 

YSZ is the usual material for use in solid oxide fuel cells. Another interesting application of stabilized zirconia is in the detection of oxygen, where it is used in both oxygen meters and ojg gen sensors, which are based on a specialized electrochemical cell (Section 5.4.4). 

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