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| 2. |
- Andersson, Mike, et al.
(author)
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SiC-FET sensors for selective and quantitative detection of VOCs down to ppb level
- 2016
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In: Procedia Engineering. - : Elsevier. - 1877-7058. ; 168, s. 216-220
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Journal article (peer-reviewed)abstract
- With the increased interest in development of cheap, simple means for indoor air quality monitoring, and specifically in relation to certain well-known pollutant substances with adverse health effects even at very low concentrations, such as different Volatile Organic Compounds (VOCs), this contribution aims at providing an overview of the development status of the silicon carbide field effect transistor (SiC FET) based sensor platform for ppb level detection of VOCs. Optimizing the transducer design, the gas-sensitive material(s) composition, structure and processing, its mode of operation - applying temperature cycled operation in conjunction with multivariate data evaluation - and long-term performance it has been possible to demonstrate promising resultsregarding the sensor technology’s ability to achieve both single-digit ppb sensitivity towards e.g. naphthalene as well as selective detection of individual substances in a mixture of different VOCs.
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| 3. |
- Huotari, Joni, et al.
(author)
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Gas sensing properites of pulsed laser deposited vanadium oxide thin films
- 2012
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In: IMCS 2012. - 9783981348422 ; , s. 279-282
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Conference paper (other academic/artistic)abstract
- Vanadium oxide thin films were fabricated by pulsed laser deposition (PLD). The crystal structure and symmetry of the deposited films was studied with X-ray diffraction (XRD) and Raman spectroscopy, respectively. The surface morphology was studied with atomic force microscope (AFM). The thin films consisted mostly of V2O5 phase of vanadium oxides, but also of another phase, which is generally found in form of nanotubes. The measured optical transmission spectra of the films also supported the existence of different phases. The electrical resistivity of the films as a function of temperature behaved like in a typical semiconductor. The gas sensing properties of the films were characterized for different NO concentrations. The results showed a response to NO, which varied from oxidative to reducing according to the film composition.
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| 4. |
- Huotari, Joni, et al.
(author)
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Gas Sensing Properties of Pulsed Laser Deposited Vanadium OxideThin Films with Various Crystal Structures
- 2013
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In: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 187:SI, s. 386-394
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Journal article (peer-reviewed)abstract
- Vanadium oxide thin films were fabricated by pulsed laser deposition. The crystal structure and symmetry of the deposited films were studied with X-ray diffraction and Raman spectroscopy, respectively. The film microstructure was also studied with atomic force microscopy and scanning electron microscopy. The thin film crystal structures varied between almost pure V2O5 phase and another phase, suggested being V7O16, generally found in samples composed of nanotubes and identified as VOx-NT. The measured optical transmission spectra of the films also supported the existence of two different phases. The electrical resistivity of the films as a function of temperature behaved like in a typical semiconductor. The gas sensing properties of the films were characterized for different NOx, CO and H-2 concentrations. The results showed a response to NOx and H-2, which varied from oxidative to reducing according to the film composition and gas background environment. Only very small response was seen towards CO. Gas response and resistivity measurements indicated that the VOx-NT-type phase has both n-type and p-type conduction mechanisms.
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| 5. |
- Huotari, Joni, et al.
(author)
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Nanostructured Mixed Phase Vanadium Oxide Thin Films as Highly Sensitive Ammonia Sensing Material
- 2014
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In: Procedia Engineering. - : Elsevier. - 1877-7058. ; 87, s. 1035-1038
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Journal article (peer-reviewed)abstract
- Pulsed laser deposition was used to produce vanadium oxide thin films on oxidized silicon substrates. Structural characterization concluded that the films consisted of two phases, orthorombic V2O5 and triclinc V7O16. Thin films performance as conductometric gas sensors was tested and they were found to be sensitive to ammonia gas already at ppb-level concentrations. Also selectivity of NH3 to NO was high. The cross-sensitivity measurements between ammonia and NO showed that the responses to these gases can be discriminated from each other even at 20 ppm concentrations. This is promising result from selective catalytic reduction point of view.
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| 6. |
- Huotari, Joni, et al.
(author)
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Pulsed laser deposition of metal oxide nanoparticles, agglomerates, and nanotrees for chemical sensors
- 2015
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In: Eurosensors 2015. - : Procedia Engineering. ; , s. 1158-1161
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Conference paper (peer-reviewed)abstract
- Pulsed laser deposition (PLD) was used to prepare WO3, ZnO-modified SnO2, and V2O5 nanostructures as gas sensing materials on top of commercial SGX Sensortech MEMS microheater platforms. The layers were formed of different types of nanostructures including nanoparticles, agglomerates, and nanotrees with fractal-like growth. Clear dependency between the deposition parameters, structural morphology, and gas sensing performance was found. The sensing materials were found to be sensitive to different types of gaseous species, so that WO3 and SnO2 had very good response up to 600% to 50 ppm NO, and V2O5 up to -35% to 20 ppm NH3, respectively.
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| 7. |
- Huotari, Joni, et al.
(author)
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Structural study of nanostructured mixed phase vanadium oxide thin films
- 2013
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In: ICE, International Conference on Electroceramics, 2013.
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Conference paper (other academic/artistic)abstract
- The studied vanadium oxide thin films were found to be composed of V2O5 phase and of V7O16 phase, shown by XRD and Raman spectroscopy studies. AFM, SEM and STEM studies confirmed the varying surface potential, roughness according to the phase structure and a clear porosity was found in the film with mixed phased structure. Also some pillar type nanostructures were observed in the films with V7O16 phase present.
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| 8. |
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| 9. |
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| 10. |
- Lloyd Spetz, Anita, et al.
(author)
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Chemical sensor systems for emission control from combustions
- 2012
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In: IMCS 2012. - 9783981348422 ; , s. 635-638
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Conference paper (other academic/artistic)abstract
- Environmental and health concern has increased the importance to monitor and control emissions from combustion processes like toxic gases and particulate matter. The SiC-FET technology offers versatile and powerful sensors for gas detection also in combination with combustion of particles. Emission control has been demonstrated e.g. for small and medium sized power plants and diesel exhausts. The potential danger of nanoparticles makes such detectors interesting not only for detection of concentration and size of particles but also detection of the content of particles. The SiC-FET technology lends itself for smart sensing and smart data evaluation, which largely improves the information from such a sensor system. Here we report progress on the sensor technology itself, the application of a sensor system as an alarm for ammonia emission and preliminary results of particle detection.
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