Electrochemical gas sensors

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

Electrochemical gas sensor, 13 589 Electrochemical grinding, 9 603 Electrochemical machining (ECM), 9 590-606... 

An entirely different selectivity principle known as phase equilibrium comes into play in high-temperature ionic conductors. Many important gases dissolve in ionic solids at elevated temperatures. However, the solubility is rather sharply defined for the gas and the solid by the lattice parameters and the size of the gas molecule. The best example is the solubility of oxygen in zirconium dioxide. When Z1O2 is doped with yttrium ions, it exhibits a high mobility for the O anion. The solubility and anion mobility then become the basis for several electrochemical gas sensors, using yttria-stabilized zirconia (YSZ). 

In recent years, gas sensors operating at room temperature are becoming increasingly more important in many fields. These sensors can be used as so called "cordless sensors", because they need no external electric sources to heat the sensor elements. Although electrochemical gas sensors which utilize liquid electrolytes are available to detect inorganic gases, e.g., 02, CO, Cl2, H2S, etc. at room temperature (1-3), they often have time-related problems such as leakage and corrosion. The problems are minimized if solid electrolytes are used in place of liquid electrolytes. 

Weppner, W. (1987) Solid-state electrochemical gas sensors. Sens. Actuators 12, 107-19. 

Zhuiykov, S. and Miura, N. (2005) Solid-state electrochemical gas sensors for emission control, in Materials for Energy Conversion Devices (eds C.C. Sorrell, S. Sugihara and J. Nowotny), Woodhead Publ. Ltd, Cambridge, UK, pp. 303-35. 

ELECTROCHEMISTRY OF ZIRCONIA SOLID ELECTROLYTES AS THE BASIS FOR UNDERSTANDING ELECTROCHEMICAL GAS SENSORS... 

The proposed methodology for computer-aided optimal design in the development of YSZ-based gas sensors comprises three phases. Firstly, the complete mathematical model with distributed temporal and spatial parameters for electrochemical gas sensors is presented as a system of the differential equations in private derivatives of parabolic and hyperbolic types. The complexity of physical and chemical interactions, represented in this model, allows performing a mathematical description of the electrochemical gas sensors toward standardization of the calculating procedures. The complete mathematical model and the algorithm of transfer from the complete... 

By using the deduction principle, the complete mathematical model of the electrochemical gas sensors with distributed parameters can be transformed to the mathematical models of the specific gas sensors, which is important for organization of their optimal design. 

FIGURE 2.3 Schematic presentation of the interaction of the solid electrolyte oxygen sensor with gas environment 1-6 stages of interaction. (From Zhniykov, S., Mathematical model of electrochemical gas sensors with distributed temporal and spatial parameters and its transformation to models of the real YSZ-based sensors. Ionics 12 (2006) 135-148. With kind permission of Springer Science and Business Media.)... 

Zhuiykov, S., Mathematical model of electrochemical gas sensors with distributed temporal and spatial parameters and its transformation to models of the real YSZ-based sensors, Ionics 12 (2006) 135-148. 

Tierney M J and Kim H-0 L 1993 Electrochemical gas sensor with extremely fast response times Anal. Chem. 65 3435-40... 

Electrochemical gas sensors detect gases based on the electromotive force(EMF) or the current of an electrochemical cell due to the electrochemical reaction of a particular gas. Solid electrolyte which a specific ion can selectively permeate is used as a diaphragm. Potentiometric type gas sensors have been most widely adopted. Among them potentiometric oxygen sensors composed of partial stabilized zirconia have already had practical application and heen extensively used for the feedback control of the air-fuel ratio of automobile engines. The oxygen sensor elements are composed of the following electrochemical cell. 

Numbers of detectable gases have been increased since Gauthier et al.[3] first proposed the feasibility of solid electrolyte gas sensors for SOj, NOj, CO and so on. Moreover the couple of a metal oxide solid electrolyte and an auxiliary electrode, investigated recently, makes it possible for stable operation and disuse of a reference gas. Electrochemical gas sensors has a strong point of detecting gases selectively because only one kind of ion can permeate through... 

The Electrochemistry of Gases of Medical Interest and Electrochemical Gas Sensors... 

The electrochemistry of gases of medical interest and electrochemical gas sensors... 

One of the most common types of gas sensor sold is the electrochemical gas sensor however, although these are low power, it is not possible to integrate this type of sensor and the necessary circuits on the same chip. This is because it requires signihcant volumes of liquid electrolytes and non-CMOS catalytic materials, such as platinum or silver electrodes. Another common gas sensor is based on infrared absorption but these require high power for the source and non-CMOS optical band-pass filters. They are also even more expensive than electrochemical sensors at 50 or more. 

Plashnitsa,V.V.,Elumalai,P.,Fujio,Y. and Miura,N. (2009), Zirconia-based electrochemical gas sensors using nano-structured sensing materials aiming at detection of automotive exhausts , ElectrochimicaActa, 54,25,6099-106. 

Lastly, electrochemical gas sensors can be based on ceramic Zr02 materials that at hlg temperatures act as oxide Ion carriers. These sensors can operate both on potentiometrlc and amperometrlc (36) principles and have been of great interest for dloxygen partial pressure sensors In harsh environments like Internal combustion engines. 

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