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Wingbrant, Helena
Publikasjoner (10 av 22) Visa alla publikasjoner
Lloyd-Spets, A., Sundgren, H., Thunér, B., Wingbrant, H., Belov, I., Svenningstorp, H. & Leisner, P. (2006). CFD analysis of packaging and mounting solutions for SiC-based gas sensors in automotive applications. , 4(1), 29-37
Åpne denne publikasjonen i ny fane eller vindu >>CFD analysis of packaging and mounting solutions for SiC-based gas sensors in automotive applications
Vise andre…
2006 (engelsk)Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Simulation-based guidelines were developed for designing tube-mounted gas sensors in the exhaust pipes of diesel and petrol engines, taking into account thermal constraints and gas flow conditions. Different block and tube mounting alternatives for SiC-based gas sensors were studied by means of temperature measurements and simulation of steady state heat transfer and gas flow. Design variables included the number of fins in the heat sink mounted on the inlet tube, the inlet construction, the mounting tube orientation, and the micro-heater substrate placement inside the mounting tube. The most preferable tube mounting design was determined with respect to the thermal performance of the sensor structure and with respect to the gas flow parameters, which are important for the sensor's selectivity, sensitivity and response time. Copyright © 2006 American Scientific Publishers All rights reserved.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-35726 (URN)10.1166/sl.2006.002 (DOI)28320 (Lokal ID)28320 (Arkivnummer)28320 (OAI)
Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2014-01-09
Wingbrant, H., Persson, M., Åbom, A. E., Eriksson, M., Andersson, B., Simko, S., . . . Lloyd Spetz, A. (2006). Co-sputtered metal and SiO2 layers for use in thick-film MISiC NH3 sensors. IEEE Sensors Journal, 6(4), 887-897
Åpne denne publikasjonen i ny fane eller vindu >>Co-sputtered metal and SiO2 layers for use in thick-film MISiC NH3 sensors
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2006 (engelsk)Inngår i: IEEE Sensors Journal, ISSN 1530-437X, Vol. 6, nr 4, s. 887-897Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

High-temperature metal-insulator-silicon-carbide (MISiC) sensors are currently under development for use as NH3 sensors in selective-catalytic-reduction (SCR) systems in diesel engines or non-SCR (NSCR) systems in boilers. The detection of NH3 by these sensors requires the presence of triple points where the gas, the metal, and the insulator meet. These triple points have traditionally been located at the interface between the insulator and a porous metal. However, to facilitate the long-term stability of the devices when used in a harsh environment, a nonporous gate material would be preferred. Here, the behavior of the samples where such triple points have been introduced in a dense film through cosputtering of the insulator (SiO 2), and either Pt or Ir is studied. The NH3 sensitivity of the materials was found to be in accordance with the earlier investigations on Si-based samples with cosputtered gate materials. Several metal-to-insulator ratios for each of the metals Pt and Ir were studied. The sensitivity of the layers as well as their selectivity to different concentrations of NH3 at temperatures ranging from 150 degC to 450 degC was investigated. The films containing 60%-70% Pt or Ir were found to give a high sensitivity toward NH3. These samples were shown to be sensitive also to propylene and H2 but were rather insensitive to NO and CO.

Emneord
Ammonia, cosputtered films, iridium, metal insulator silicon carbide (MISiC), platinum, selective catalytic reduction (SCR), silicon dioxide (SiO2), thick film
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-13410 (URN)10.1109/JSEN.2006.877973 (DOI)
Tilgjengelig fra: 2005-11-10 Laget: 2005-11-10 Sist oppdatert: 2015-03-24
Lloyd-Spets, A., Nakagomi, S., Wingbrant, H., Andersson, M., Salomonsson, A., Roy, S., . . . Yakimova, R. (2006). New materials for chemical and biosensors. Materials and Manufacturing Processes, 21(3), 253-256
Åpne denne publikasjonen i ny fane eller vindu >>New materials for chemical and biosensors
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2006 (engelsk)Inngår i: Materials and Manufacturing Processes, ISSN 1042-6914, E-ISSN 1532-2475, Vol. 21, nr 3, s. 253-256Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Wide band gap materials such as SiC, AlN, GaN, ZnO, and diamond have excellent properties such as high operation temperature when used as field effect devices and a high resonating frequency of the substrate materials used in piezoelectric resonator devices. Integration of FET and resonating sensors on the same chip enables powerful miniaturized devices, which can deliver increased information about a gas mixture or complex liquid. Examples of sensor devices based on different wide band gap materials will be given.

Emneord
AlN, Biosensors, Catalytic metals, Chemical sensors, Diamond, FET, GaN, High frequency, High temperature, Resonators, SAW, SiC, Thin film, Wide band gap materials, ZnO
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-50293 (URN)10.1080/10426910500464495 (DOI)
Tilgjengelig fra: 2009-10-11 Laget: 2009-10-11 Sist oppdatert: 2017-12-12
Wingbrant, H. & Lloyd-Spetz, A. (2006). The influence of catalytic activity on the phase transition governed binary switch point of MISiC-FET lambda sensors. Applied Surface Science, 252(20), 7473-7486
Åpne denne publikasjonen i ny fane eller vindu >>The influence of catalytic activity on the phase transition governed binary switch point of MISiC-FET lambda sensors
2006 (engelsk)Inngår i: Applied Surface Science, ISSN 1530-437X, Vol. 252, nr 20, s. 7473-7486Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A metal insulator silicon carbide field effect transistor (MISiC-FET) sensor with a catalytic metal gate is currently under development for detecting the lambda value, or air-to-fuel ratio, of gasoline exhausts. It has been noticed that a change from a low to a high signal level of the sensor occurs at a lambda value above 1.00, which is an oxidizing atmosphere. The exact location of the switch point depends both on the kind of gas and gas concentrations chosen to obtain a specific lambda value. The switch point would rather have been expected at 1.00, which is at stoichiometry, irrespective of the composition of the gas mixture. The origin of this phenomenon is studied here by exposing the sensor to lambda stairs while changing different operating parameters. An increase in catalytic activity has been observed to move the switch point of the device towards a lambda value of 1.00. A similar effect is achieved when decreasing the flow or increasing the temperature of operation of the device. The behavior is explained through the introduction of mass transport limitations in the measurement cell, and the difference in diffusion constants and sticking coefficients among the gases when reaction limitation prevails.

Emneord
MISiC-FET; Catalytic activity; Binary switch point; Phase transition; Lambda
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-13409 (URN)10.1016/j.apsusc.2005.09.003 (DOI)
Tilgjengelig fra: 2005-11-10 Laget: 2005-11-10 Sist oppdatert: 2014-01-09
Lloyd-Spets, A., Andersson, M., Petersson, H., Wingbrant, H., Unéus, L., Svenningstorp, H., . . . Holmberg, M. (2005). Gas sensor arrays for combustion control. In: Professor Rudolph A. Marcus, Nobel Prize Laureate (Ed.), Encyclopedia of Sensors, eds.: (pp. 139-154). California: American Scientific Publishers
Åpne denne publikasjonen i ny fane eller vindu >>Gas sensor arrays for combustion control
Vise andre…
2005 (engelsk)Inngår i: Encyclopedia of Sensors, eds. / [ed] Professor Rudolph A. Marcus, Nobel Prize Laureate, California: American Scientific Publishers , 2005, s. 139-154Kapittel i bok, del av antologi (Annet vitenskapelig)
Abstract [en]

The applications of sensors range from medical diagnostics to industrial manufacturing and to defense and national security applications. When an area spans such a large diversity of research, and where research from many different countries is also involved, a review of these developments becomes especially useful. Because it bridges science and technology the field also provides a desired interaction between researchers and research in technologically advanced and developing countries. The present series of volumes, "The Encyclopedia of Sensors" , the first of its kind, is intended to provide a timely compendium of the entire field. As such it can be expected to play a significant role in worldwide future progress and understanding."

sted, utgiver, år, opplag, sider
California: American Scientific Publishers, 2005
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-35723 (URN)28314 (Lokal ID)1-58883-056-X (ISBN)28314 (Arkivnummer)28314 (OAI)
Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2014-01-09bibliografisk kontrollert
Nakagomi, S., Fukumura, A., Kokubun, Y., Savage, S., Wingbrant, H., Andersson, M., . . . Lloyd-Spets, A. (2005). Influence of gate bias of MISiC-FET gas sensor device on the sensing properties. Sensors and actuators. B, Chemical, 108, 501-507
Åpne denne publikasjonen i ny fane eller vindu >>Influence of gate bias of MISiC-FET gas sensor device on the sensing properties
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2005 (engelsk)Inngår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 108, s. 501-507Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The influence of gate bias on the gas sensing properties of SiC-based field effect transistors with catalytic gate and a buried short channel has been studied. The drain current-voltage (I-d-V-D) characteristics of the device reveal non-saturation property, which is a consequence of the short channel design. The drain current is larger in hydrogen ambient than in oxygen ambient at the same drain voltage. The threshold voltage decreases with increasing positive gate bias, and increases with increasing negative gate bias. When a positive bias is applied to the gate, the I-d-V-D characteristics reveal a tendency to saturate. A positive gate bias increases the drain voltage response to hydrogen, as compared with a negative applied gate bias. However, a positive gate bias decreases the stability of the device signal. A change in the channel resistivity is the main reason for the change in the electrical properties when a positive gate bias is applied. A physical model that explains the influence of the gate bias has been studied, and the behavior of the barrier height in the channel was estimated by using the temperature dependence of the I-d-V-D characteristics.

Emneord
current-voltage, JFET, MISiC-FET, gate bias, buried short channel
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-30147 (URN)10.1016/j.snb.2004.11.057 (DOI)15630 (Lokal ID)15630 (Arkivnummer)15630 (OAI)
Tilgjengelig fra: 2009-10-09 Laget: 2009-10-09 Sist oppdatert: 2017-12-13
Lloyd-Spets, A., Andersson, M. & Wingbrant, H. (2005). MISiC-FET NH3 sensors for SCR control in exhaust and flue gases. In: Rudolph A. Marcus, Nobel Prize Laureate (Ed.), Encyclopedia of Sensors, eds.: (pp. 205-218). California: American Scientific Publishers
Åpne denne publikasjonen i ny fane eller vindu >>MISiC-FET NH3 sensors for SCR control in exhaust and flue gases
2005 (engelsk)Inngår i: Encyclopedia of Sensors, eds. / [ed] Rudolph A. Marcus, Nobel Prize Laureate, California: American Scientific Publishers , 2005, s. 205-218Kapittel i bok, del av antologi (Annet vitenskapelig)
Abstract [en]

    The applications of sensors range from medical diagnostics to industrial manufacturing and to defense and national security applications. When an area spans such a large diversity of research, and where research from many different countries is also involved, a review of these developments becomes especially useful. Because it bridges science and technology the field also provides a desired interaction between researchers and research in technologically advanced and developing countries. The present series of volumes, "The Encyclopedia of Sensors" , the first of its kind, is intended to provide a timely compendium of the entire field. As such it can be expected to play a significant role in worldwide future progress and understanding."

sted, utgiver, år, opplag, sider
California: American Scientific Publishers, 2005
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-35724 (URN)28316 (Lokal ID)1-58883-056-X (ISBN)28316 (Arkivnummer)28316 (OAI)
Tilgjengelig fra: 2009-10-10 Laget: 2009-10-10 Sist oppdatert: 2014-01-09bibliografisk kontrollert
Wingbrant, H., Lundén, M. & Lloyd Spetz, A. (2005). Modifications of the Gate Material to Increase the Long-Term Stability of Field Effect Transistor Lambda Sensors. Sensor Letters, 3(3), 225-230
Åpne denne publikasjonen i ny fane eller vindu >>Modifications of the Gate Material to Increase the Long-Term Stability of Field Effect Transistor Lambda Sensors
2005 (engelsk)Inngår i: Sensor Letters, ISSN 1546-198X, Vol. 3, nr 3, s. 225-230Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The MISiC-FET Pt/TaSix sensor has been shown previously to work well for measuring the lambda value, or the air-to-fuel ratio, of gasoline engine exhausts. However, the catalytic gate metal that is crucial for the sensing properties tends to restructure in harsh exhaust gases, which affects the behavior of the device. To increase the long-term stability of the sensor several modifications of the sensing layer, such as depositing a protective film of SiO2 on top of the metal or co-sputtering the catalytic metal with SiO2, have been studied and are presented here. The sensitivity and long-term stability of these films compared to the Pt/TaSix layers traditionally used for MISiC-FET lambda sensors have been investigated through laboratory measurements and SEM (scanning electron microscope) analyses. It was found that the catalytic metal films with a protective layer restructured much less than those without, but that the protective layer decreased the sensitivity of the sensors. On the other hand, the sensor gained linear characteristics when exposing it to lambda stairs. Mixing Ir and SiO2 also gave less restructuring compared with the reference samples, while maintaining a high sensitivity to lambda.

Emneord
Cold start sensors; Sic-fet; Lambda; Long-term stability; Linear
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-13411 (URN)10.1166/sl.2005.034 (DOI)
Tilgjengelig fra: 2005-11-10 Laget: 2005-11-10 Sist oppdatert: 2014-01-09
Wingbrant, H. (2005). Studies of MISiC-FET sensors for car exhaust gas monitoring. (Doctoral dissertation). : Institutionen för fysik, kemi och biologi
Åpne denne publikasjonen i ny fane eller vindu >>Studies of MISiC-FET sensors for car exhaust gas monitoring
2005 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

The increasing size of the car fleet makes it important to find ways of lowering the amounts of pollutants from each individual diesel or gasoline engine to almost zero levels. The pollutants from these engines predominantly originate from emissions at cold start, in the case when gasoline is utilized, and high NOx emissions and particulates from diesel engines.

The cold start emissions from gasoline vehicles are primarily due to a high light-off time for the catalytic converter. Another reason is the inability to quickly heat the sensor used for controlling the air-to-fuel ratio in the exhausts, also called the lambda value, which is required to be in a particular range for the catalytic converter to work properly. This problem may be solved utilizing another, more robust sensor for this purpose.

One way of treating the high NOx levels from diesel engines is to introduce ammonia in the exhausts and let it react with the NOx in a special catalytic converter to form nitrogen gas and water, which is called SCR (selective catalytic reduction). However, in order to make this system reduce NOx efficiently enough for meeting future legislations, closed loop control is required. To realize this type of system an NOx or ammonia sensor is needed.

This thesis presents the efforts made to test the SiC-based field effect sensor device both as a cold start lambda sensor for gasoline engines and as an NH3 sensor for SCR systems in diesel engines.

The MISiC (metal insulator silicon carbide) lambda sensor has proven to be both sensitive and selective to lambda, and its properties have been studied in lambda stairs both in gasoline engine exhausts and in the laboratory. There is, however, a small cross-sensitivity to CO. The influence of metal gate restructuring on the linearity of the sensor has also been investigated. The metal tends to form islands by time, which decreases the catalytic activity and thereby gives the sensor, which is binary when fresh, a linear behavior. Successful attempts to prevent the restructuring through depositing a protective layer of insulator on top of the metal were made. The influence of increasing the catalytic activity in the measurement cell was also studied. It was concluded that the location of the binary switch point of MISiC lambda sensors could be moved towards the stoichiometric value if the consumption of gases in the measurement cell was increased.

The MISiC NH3 sensor for SCR systems has been shown to be highly sensitive to ammonia both in laboratory and diesel engine measurements. The influence of other diesel exhaust gas components, such as NOx, water or N2O has been found to be low. In order to make the ammonia sensor more long-term stable experiments on samples with different types of co-sputtered Pt or Ir/SiO2 gas-sensitive layers were performed. These samples turned out to be sensitive to NH3 even though they were dense and NH3 detection normally requires porous films.

The speed of response for both sensor types has been found to be fast enough for closed loop control in each application.

sted, utgiver, år, opplag, sider
Institutionen för fysik, kemi och biologi, 2005
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 931
Serie
Emneord
field effect sensor, gas detection, selective catalytic reduction, lambda, cold start, ammonia, silicon carbide, engine exhaust
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-4674 (URN)91-85297-61-5 (ISBN)
Disputas
2005-04-22, Hörsal Planck, Fysikhuset, Campus Valla, Linköpings univeristet, Linköping, 10:15 (engelsk)
Opponent
Veileder
Merknad
On the day of the ublic defence of the doctoral thesis, the status of article IV was: accepted, article V was: submitted and article VII was: manuscript.Tilgjengelig fra: 2005-11-10 Laget: 2005-11-10 Sist oppdatert: 2014-01-09
Andersson, M., Wingbrant, H. & Lloyd-Spets, A. (2005). Study of CO response of SiC based field effect gas sensors. In: IEEE Sensors 2005,2005 (pp. 105).
Åpne denne publikasjonen i ny fane eller vindu >>Study of CO response of SiC based field effect gas sensors
2005 (engelsk)Inngår i: IEEE Sensors 2005,2005, 2005, s. 105-Konferansepaper, Publicerat paper (Fagfellevurdert)
Emneord
CO response, SiC, field effect gas, sensor
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-30832 (URN)16480 (Lokal ID)16480 (Arkivnummer)16480 (OAI)
Tilgjengelig fra: 2009-10-09 Laget: 2009-10-09 Sist oppdatert: 2014-01-09
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