Sven Wiegärtner

Conductometric soot sensor for automotive exhausts: initial studies.

In order to reduce the tailpipe particulate matter emissions of Diesel engines, Diesel particulate filters (DPFs) are commonly used. Initial studies using a conductometric soot sensor to monitor their filtering efficiency, i.e., to detect a malfunction of the DPF, are presented. The sensors consist of a planar substrate equipped with electrodes on one side and with a heater on the other. It is shown that at constant speed-load points, the time until soot percolation occurs or the resistance itself are reproducible means that can be well correlated with the filtering efficiency of a DPF. It is suggested to use such a sensor setup for the detection of a DPF malfunction.

Solid-state potentiometric CO 2 -sensor in thick film technology for breath analysis

A solid-state potentiometric CO<inf>2</inf>-sensor of the type CO<inf>2</inf>, O<inf>2</inf>, Au, Li<inf>2</inf>CO<inf>3</inf>-BaCO<inf>3</inf> | Nasicon | Na<inf>2</inf>Ti<inf>6</inf>O<inf>13</inf>-TiO<inf>2</inf>, Au, O<inf>2</inf>, CO<inf>2</inf> was fully manufactured in planar thick-film technology. Due to an integrated screen-printed heater on the rear side, the sensor can be applied in a small tube for breath analysis, despite its high working temperature of 525 °C. The sensor is insensitive to variations of the oxygen partial pressure and follows strictly the Nernst equation. Based on this behavior, the presented sensor cell is suitable for exhale air analysis.

Sensor Tool for Fast Catalyst Material Characterization

For the development of catalyst materials a novel sensor tool is presented. It can determine catalyst light-off temperatures. The device measures temperature changes (exothermicities) due to catalytic reactions of the material which is coated on a very small catalyst coating area directly on the sensor device. By temperature modulation via an integrated heater, light-off temperature characteristics can be determined within a few minutes. In the present contribution, the sensor setup is introduced and several experimental results for an exemplarily investigated Pt-loaded Al2O3 catalyst are shown with typical exhaust gas components and with mixtures of their components in a lean base gas atmosphere. Several typical findings are light-off hysteresis, CO poisoning, alkane light-off-behavior or acetylene poisoning.

Evaluation of screen-printable type S (Pt-PtRh) thermocouples on different ceramic substrates

Abstract The application of thermocouples as temperature sensors has been well known and has already been established for many years. However, for classical thick-film technology using screen-printing and firing, no standardized solutions exist. The here-presented newly developed PtRh thick-film compositions (90% Pt,10% Rh) allows to construct thick-film type S thermocouples (Pt/PtRh), following the IEC temperature characteristics. They can be fired in air, and therefore can be easily integrated into existing thick-film components and devices. In an earlier study, the new Pt-Rh composition was successfully tested on alumina substrates. Their electrical characteristics is equal with classical wire type S thermocouples. This study continues the investigations of thick-film thermocouples. We tested the newly developed pastes for high temperature applications on alumina substrates and evaluated the application of the new screen-printable type S thermocouples on LTCC ceramics. Three possible configurations wer...