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Open AccessArticle

Conductometric Soot Sensors: Internally Caused Thermophoresis as an Important Undesired Side Effect

Bayreuth Engine Research Center (BERC), Department of Functional Materials, University of Bayreuth, 95440 Bayreuth, Germany
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Sensors 2018, 18(10), 3531; https://doi.org/10.3390/s18103531
Received: 17 September 2018 / Revised: 12 October 2018 / Accepted: 15 October 2018 / Published: 19 October 2018
(This article belongs to the Section Chemical Sensors)
Particulate matter sensors are of interest for application in the exhaust of any combustion processes, especially for automotive aftertreatment systems. Conductometric soot sensors have been serialized recently. They comprise planar interdigital electrodes (IDE) on an insulating substrate. Between the IDEs, a voltage is applied. Soot deposition is accelerated by the resulting electric field due to electrophoresis. With increasing soot deposition, the conductance between the IDE increases. The timely derivative of the conductance can serve as a sensor signal, being a function of the deposition rate. An increasing voltage between the IDE would be useful for detecting low particle exhausts. In the present study, the influence of the applied voltage and the sensor temperature on the soot deposition is investigated. It turned out that the maximum voltage is limited, since the soot film is heated by the resulting current. An internally caused thermophoresis that reduces the rate of soot deposition on the substrate follows. It reduces both the linearity of the response and the sensitivity. These findings may be helpful for the further development of conductometric soot sensors for automotive exhausts, probably also to determine real driving emissions of particulate matter. View Full-Text
Keywords: particulate matter sensors; exhaust gas aftertreatment; particulate filter; soot deposition; electrophoresis; thermophoresis; dynamometer particulate matter sensors; exhaust gas aftertreatment; particulate filter; soot deposition; electrophoresis; thermophoresis; dynamometer
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Hagen, G.; Spannbauer, C.; Feulner, M.; Kita, J.; Müller, A.; Moos, R. Conductometric Soot Sensors: Internally Caused Thermophoresis as an Important Undesired Side Effect. Sensors 2018, 18, 3531.

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