| 1. |
- Andersson, Mike, et al.
(författare)
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On the CO response mechanism of SiC based field effect gas sensors
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards carbon monoxide (CO) at varying oxygen (O2) concentrations and over a wide range of temperatures have been investigated in detail at atmospheric pressure. The influence of hydrogen (H2) on the CO response was also studied. Sensor devices with thin, porous as well as dense, homogeneous Pt films on top of both silicon dioxide (SiO2) and magnesium oxide (MgO) as insulator materials were investigated in this study. The reaction products generated on the sensor surfaces were also monitored with a mass spectrometer connected to the gas flow just downstream of the sensor location and the results compared to CO oxidation characteristics over Pt/SiO2 and to some extent Pt/MgO catalysts as reported in literature. By correlating the response characteristics of these devices with CO2 formation and hydrogen consumption on the sensor surfaces, strong indications for a CO response mechanism involving a CO induced increased sensitivity to background hydrogen have been obtained, this mechanism being hypothesized to be the only one behind the CO sensitivity of devices with dense Pt metal contacts. The results also give further support to the idea that also other processes than an increased sensitivity to background hydrogen contribute to the CO response of sensor devices with a porous platinum film as the metal contact, one candidate being the removal of oxygen anions from the surface of exposed oxide areas through the oxidation reaction with CO.
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| 2. |
- Andersson, Mike, et al.
(författare)
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On the response mechanism of SiC based field effect gas sensors towards non-hydrogen containing species and specifically NO
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards nitrogen oxide (NO) for both low as well as relatively high background oxygen (O2) concentrations and different temperatures have been investigated at atmospheric pressure. Devices with both porous and dense Pt metal gate contacts have been investigated and the results seem to confirm the theories and results from earlier measurements regarding the requirement of porous metal films for the existence of a response to NO for this kind of sensor device. The results also suggest that no NO induced increased sensitivity to background hydrogen exists, at least it does not play any role in the observed NO sensitivity, as opposed to what has been suggested in the case of CO. The obtained results are also discussed in relation to some of the proposed sensing mechanisms for non-hydrogen containing substances and in comparison to NO reduction characteristics on Pt/SiO2 catalysts, as reported in literature. The results further give some indications about also some other process/ processes being important for the response of SiC based field effect sensors towards NO than just adsorption/desorption.
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| 3. |
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| 4. |
- Belov, Ilja, et al.
(författare)
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CFD analysis of packaging and mounting solutions for SiC-based gas sensors in automotive applications
- 2006
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Ingår i: Sensor Letters. - 1546-198X. ; 4:1, s. 29-37
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Belov, Ilja, et al.
(författare)
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Thermal and flow analysis of SiC-based gas sensors for automotive applications
- 2004
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Ingår i: Proceedings of the 5th International Conference on Thermal and Mechanical Simulation and Experiments in Microelectronics and Microsystems, 2004. - : IEEE. - 0780384202 ; , s. 475-482
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Konferensbidrag (refereegranskat)abstract
- Different block and tube mounting alternatives for SiC-based gas sensors were studied by means of temperature measurements and simulation of heat transfer and gas flow for steady state conditions. The most preferable tube mounting design was determined. 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 flow conditions.
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| 6. |
- Briand, D., et al.
(författare)
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Modulated operating temperature for MOSFET gas sensors : Hydrogen recovery time reduction and gas discrimination
- 2003
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 93:1-3, s. 276-285
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This communication presents a modulated mode of operation for MOSFET gas sensors. A low-power micromachined device allows pulsing the temperature of MOSFET gas sensors with a time constant less than 100ms. Modulating the temperature during the gas exposure modifies the kinetics of the gas reactions with the sensing film. The way the sensor response is modified by the temperature modulation depends on the sensor "history", on the nature of the surrounding gaseous atmosphere, and on the type of materials used as catalytic sensing film. Pulsing the temperature up just after the gas exposure can reduce the recovery time for specific applications, such as for hydrogen detection. Cycling the temperature can allow the discrimination between different gas mixtures. Discrimination was shown for gaseous mixtures of hydrogen and ammonia in air. The results obtained indicate that a "smart" combination of sample and temperature profile could be used to expand the information content in the sensor response. © 2003 Elsevier Science B.V. All rights reserved.
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| 7. |
- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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Gas sensor arrays for combustion control
- 2005
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Ingår i: Encyclopedia of Sensors, eds.. - California : American Scientific Publishers. - 158883056X ; , s. 139-154
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- 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."
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| 8. |
- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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MISiC-FET NH3 sensors for SCR control in exhaust and flue gases
- 2005
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Ingår i: Encyclopedia of Sensors, eds.. - California : American Scientific Publishers. - 158883056X ; , s. 205-218
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- 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."
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| 9. |
- Lloyd-Spets, Anita, et al.
(författare)
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MISiCFET chemical gas sensors for high temperature and corrosive environment applications
- 2002
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 389-3, s. 1415-1418
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Tidskriftsartikel (refereegranskat)abstract
- A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The buried gate design allows the sensor to operate at high temperatures, routinely up to 600degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.
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| 10. |
- Lloyd-Spets, Anita, et al.
(författare)
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New materials for chemical and biosensors
- 2006
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Ingår i: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 21:3, s. 253-256
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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