Sensors ceramic

Ceramic sensors are devices that provide environmental feedback by transforming a nonelectrical input into an electrical output. The applications for which these devices are used are widely varied. A brief list includes the use of sensors to determine the concentration of various gases, such as oxygen and carbon monoxide, temperature measurement devices, and pressure, radiation, and humidity sensors. Sensors have also become widely used in automotive applications. In manufacturing, because of the increasing need for waste minimization, process control, and environmentally conscious manufacturing, the increasing emphasis on sensor use and development is likely to continue to expand. The use of feedback loops in conjunction with sensors for process control/optimization has also increased in recent years. 

Sensor performance for different applications is defined by various features of the ceramic. For example, the electrical output of most pressure sensors is dependent on the bulk piezoelectric properties of a PZT ceramic. Oxygen gas sensor performance is defined by the conductivity behavior of Zr02 ceramics, which is in turn dependent on the oxygen vacancy content of the material. The performance of still other sensors, for example, ceramic thermistors, is dependent on the grain boundary characteristics of doped BaTi03 ceramics. For humidity sensors based on NiO/ZnO, the p—n junction characteristics of the interface define sensor performance. 

In general, it may be stated that the performance characteristics of a particular sensor are dependent on the bulk, grain boundary, interface, or surface properties 

As expected from the above discussion, a variety of techniques is utilized in the characterization of sensor materials. One property frequently studied is the conductivity or resistivity of the material as a function of a second parameter, such as temperature, or the pressure or concentration of a particular gaseous species. In gas concentration-sensing applications, other properties of the material, such as gas transport, are also critical for device performance and must also be characterized. 

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Furthermore, other solid-state sensors have been developed and introduced, ranging from thin film and screen-printed sensors to ceramic sensors and - latterly polymeric sensors. 

H20, humidity Capacitive polmyer sensors and ceramic sensors Thin film technology and thick film technology... 

Humidity - [SIMULTANEOUS HEAT AND MASS TRANSFER] (Vol 22) -ceramic sensors for [CERAMICS - ELECTRONIC PROPERTIES AND MATERIAL STRUCTURE] (Vol 5) -effect on barrier properties [BARRIER POLYMERS] (Vol 3) -sensors for [SENSORS] (Vol 21)... 

High Temperature Ceramic Sensors (Zirconia Cells)... 

E.Z. Tang, T.H. Etsell, and D.G. Ivey, Ceramic Sensors III, PV96-27, The Electrochemical Society Proceeding Series, The Electrochemical Society, Pennington, NJ, 1996, p.131. 

Garzon, R., Mukundan, R. and Brosha, E.L. (2001) Modeling the response of mixed potential electrochemical sensors. Proceedings of the Electrochemical Society, 2000-32 Solid-State Ionic Devices II Ceramic Sensors, The Electrochemical Society, Pennington, New Jersey, pp. 305-13. 

M., Kotzeva, V. and Kumar, R.V. (2000) Solid state ceramic sensors based on interfacing ionic conductors with semiconducting oxides. J. Eur. Ceram. Soc., 20, 2691-9. 

Akbar, S.A. (2003) Ceramic sensors for the glass industry. Ceramic Engineering and Science Proceedings, 163rd Conference on Glass Problems, 2002, The American Ceramic Society, Westerville, Ohio,... 

Wachsman, E.D. and Jayaweera, P., Selective detection of NO by differential electrode equihbria, in Solid State Ionic Devices II Ceramic Sensors, Eds. E.D. Wachsman et al., PV 2000-32, The Electrochemical Society Proceedings Series, Pennington, NJ, 2001, 298. 

A ceramic sensor element is typically composed of a substrate, electrodes, catalytic layers, and functional layers, based on various physical and chemical effects. In some cases, for example, Zr02, the substrate and functional materials are identical. 

To build up functional or protective layers, various methods from other technical industries have been adapted to the specific needs of ceramic sensor materials. Important criteria for the selection of the various technologies are the shape of the ceramic substrate (e.g., thimble or planar design), if it is co- or post-fired, if the layer material is expensive (e.g., noble metals) or inexpensive (e.g., alumina, magnesia spinel), and if the geometry and thickness need to be controlled precisely. 

Resistance-humidity characteristics of the Ti02-Sn02 ceramic sensor at 40 °C. 

Resistance (R)-humidity characteristics of the MgCrj04-Ti02 ceramic sensor at several temperatures. 

K.E. Swider-Lyons, K.M. Bussmann, D.L. Griscom, C.T. Love, D.R. Rolison, W. Dmowski, T. Egami, In Sohd State Ionic Devices II - Ceramic Sensors, E.D. Wachsman, et al., Eds., Electrochemical Society Proceedings 2000-32, 2000,48... 

Ivanovskaya M. and Bogdanov P, Effect of Nill ions on the properties of lUjOj-based ceramic sensors, Sens. Actuators B, 53, 44—53, 1998. 

Cantalini C., Sun H. T., Faccio M., Ferri G., and Pehno M., Niobium-doped a-FcjOj semiconductor ceramic sensors for the measurement of nitric oxide gases. Sens. Actuators B, 24-25, 673-677, 1995. 

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