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Contactless Impedance Sensors and Their Application to Flow Measurements
Department of Analytical Chemistry, Faculty of Science, Charles University in Prague, Albertov 2030, CZ-128 43 Prague 2, Czech Republic
Institute of Biochemistry, Third Faculty of Medicine, Cell and Molecular Biology, Charles University in Prague, Ruská 87, CZ-100 00 Prague 10, Czech Republic
* Author to whom correspondence should be addressed.
Received: 23 November 2012; in revised form: 31 January 2013 / Accepted: 1 February 2013 / Published: 27 February 2013
Abstract: The paper provides a critical discussion of the present state of the theory of high-frequency impedance sensors (now mostly called contactless impedance or conductivity sensors), the principal approaches employed in designing impedance flow-through cells and their operational parameters. In addition to characterization of traditional types of impedance sensors, the article is concerned with the use of less common sensors, such as cells with wire electrodes or planar cells. There is a detailed discussion of the effect of the individual operational parameters (width and shape of the electrodes, detection gap, frequency and amplitude of the input signal) on the response of the detector. The most important problems to be resolved in coupling these devices with flow-through measurements in the liquid phase are also discussed. Examples are given of cell designs for continuous flow and flow-injection analyses and of detection systems for miniaturized liquid chromatography and capillary electrophoresis. New directions for the use of these sensors in molecular biology and chemical reactors and some directions for future development are outlined.
Keywords: contactless detector; conductivity detection; impedance detector; permittivity detection
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MDPI and ACS Style
Opekar, F.; Tůma, P.; Štulík, K. Contactless Impedance Sensors and Their Application to Flow Measurements. Sensors 2013, 13, 2786-2801.
Opekar F, Tůma P, Štulík K. Contactless Impedance Sensors and Their Application to Flow Measurements. Sensors. 2013; 13(3):2786-2801.
Opekar, František; Tůma, Petr; Štulík, Karel. 2013. "Contactless Impedance Sensors and Their Application to Flow Measurements." Sensors 13, no. 3: 2786-2801.