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Thungström, Göran
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Publications (10 of 96) Show all publications
Ashraf, S., Niskanen, I., Kanyathare, B., Vartiainen, E., Mattsson, C., Heikkilä, R. & Thungström, G. (2019). Determination of complex refractive index of SU-8 by Kramers-Kronig dispersion relation method at the wavelength range 2.5 – 22.0 μm. Journal of Quantitative Spectroscopy and Radiative Transfer, 224, 309-311
Open this publication in new window or tab >>Determination of complex refractive index of SU-8 by Kramers-Kronig dispersion relation method at the wavelength range 2.5 – 22.0 μm
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2019 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 224, p. 309-311Article in journal (Refereed) Published
Abstract [en]

Accurate determination of the complex refractive index of SU-8 epoxy has significant for the wide variety of applications in optical sensor technology at IR range. The complex refractive index of SU-8 is determined by recording the transmission of light spectra for the wavelength range of 2.5 – 22.0 μm.  The data analysis is based on the Kramers-Kronig dispersion relation method. The method has several merits, such as ease of operation, non-contact technique, measurement accuracy, and rapid measurement. The present method is not restricted to the case of SU-8 but it is also proposed to be applicable across a broad range of applications, such as assessment of the optical properties of paints and biomedical samples.

Keywords
Complex refractive index, SU-8 epoxy, Kramers-Kronig dispersion relation method, FT-IR spectrophotometer, Infrared region
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:miun:diva-34927 (URN)10.1016/j.jqsrt.2018.11.026 (DOI)000456754800034 ()2-s2.0-85057277091 (Scopus ID)
Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2019-03-18Bibliographically approved
Niskanen, I., Forsberg, V., Zakrisson, D., Reza, S., Hummelgård, M., Andres, B., . . . Thungström, G. (2019). Determination of nanoparticle size using Rayleigh approximation and Mie theory. Chemical Engineering Science, 201(29), 222-229
Open this publication in new window or tab >>Determination of nanoparticle size using Rayleigh approximation and Mie theory
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2019 (English)In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 201, no 29, p. 222-229Article in journal (Refereed) Published
Abstract [en]

Accurate determination of the size of nanoparticles has an important role in many different scientific and industrial purposes, such as in material, medical and environment sciences, colloidal chemistry and astrophysics. We describe an effective optical method to determine the size of nanoparticles by analysis of transmission and scattering of visible spectral range data from a designed UV-Vis multi-spectrophotometer. The size of the nanoparticles was calculated from the extinction cross section of the particles using Rayleigh approximation and Mie theory. We validated the method using polystyrene nanospheres, cellulose nanofibrils, and cellulose nanocrystals. A good agreement was achieved through graphical analysis between measured extinction cross section values and theoretical Rayleigh approximation and Mie theory predictions for the sizes of polystyrene nanospheres at wavelength range 450 - 750 nm. Provided that Rayleigh approximation's forward scattering (FS)/back scattering (BS) ratio was smaller than 1.3 and Mie theory's FS/BS ratio was smaller than 1.8. A good fit for the hydrodynamic diameter of nanocellulose was achieved using the Mie theory and Rayleigh approximation. However, due to the high aspect ratio of nanocellulose, the obtained results do not directly reflect the actual cross-sectional diameters of the nanocellulose. Overall, the method is a fast, relatively easy, and simple technique to determine the size of a particle by a spectrophotometer. Consequently, the method can be utilized for example in production and quality control purposes as well as for research and development applications.

Keywords
Nanoparticles, size, Rayleigh approximation, Mie theory, spectrophotometer, nanocellulose
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-35764 (URN)10.1016/j.ces.2019.02.020 (DOI)2-s2.0-85062846560 (Scopus ID)
Available from: 2019-03-08 Created: 2019-03-08 Last updated: 2019-03-25Bibliographically approved
Ashraf, S., Mattsson, C. & Thungström, G. (2019). Fabrication and characterization of a SU8-epoxy membrane based thermopile detector with an integrated multilayered absorber structure for the mid-IR region. IEEE Sensors Journal
Open this publication in new window or tab >>Fabrication and characterization of a SU8-epoxy membrane based thermopile detector with an integrated multilayered absorber structure for the mid-IR region
2019 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748Article in journal (Refereed) Epub ahead of print
Abstract [en]

This paper reports on the fabrication and characterization of a thermopile detector with an integrated mid-infrared absorber structure. The fabricated absorber structure has shown an absorption of more than 95% in the wavelength range of 3.2 – 5.47 μm. The detector was fabricated with standard cleanroom process techniques and equipment. The serial resistance was measured at about 315 kΩ at room temperature. The photosensitivity of the detector was characterized for a signle wavelength (4.26 µm) and a band of wavelength ranging from 2.5 –5.5 µm through two different measurement setups. In the first measurement setup, the photosensitivity was estimated at 57.5 V·mm2·W-1 through a MEMS-based infrared radiation source and with an optical band-pass filter of wavelength 4.26µm. The following characterization was performed to characterise the photosensitivity of the detector in a broader wavelength range. This measurement was taken using a monochromator setup utilizing a reference photodetector for calculations of the optical power of the infrared source. The photosensitivity and the specific detectivity (D*) of the fabricated detector were measured to values of 30-92 V·W-1 and 8.0×107-2.4×108 cm·Hz1/2·W-1, respectively, in the wavelength range of 2.8 – 5 µm. The time constant was estimated to around 21 ms

Keywords
Interfermometric absorber, Thermopile, Infrared detector, SU8 epoxy, photosensitivity, Transfer matrix theory, CO2 detection
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-35525 (URN)10.1109/JSEN.2019.2896668 (DOI)
Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-04-05Bibliographically approved
Soetedjo, H., Niskanen, I., Rautkari, L., Altgen, M., Hiltunen, E., Thungström, G., . . . Räty, J. (2018). Determining the degree of heat treatment of wood by light polarization technique. European Journal of Wood and Wood Products, 76(4), 1359-1362
Open this publication in new window or tab >>Determining the degree of heat treatment of wood by light polarization technique
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2018 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 76, no 4, p. 1359-1362Article in journal (Refereed) Published
Abstract [en]

Thermal modification of wood enables the use of non-durable wood species in exterior applications, but quality control methods are required to monitor the product variability. This study tests the potential of a light polarization technique where visible light (400–500 nm) is directed through a linear polarizer to the surface of thermally modified wood to measure the reflectance. Besides an effect of the grain direction, the reflectance decreased with increasing temperature during the thermal modification process. The technique could be used for quality control, but further studies are required to understand its modes of action. 

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-33664 (URN)10.1007/s00107-018-1311-2 (DOI)000435782200029 ()2-s2.0-85045912828 (Scopus ID)
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2019-03-15Bibliographically approved
Ashraf, S., Mattsson, C., Thungström, G., Gaynullin, B. & Rödjegård, H. (2018). Evaluation of a CO2 sensitive thermopile with an integrated multilayered infrared absorber by using a long path length NDIR platform. In: I2MTC 2018 - 2018 IEEE International Instrumentation and Measurement Technology Conference: Discovering New Horizons in Instrumentation and Measurement, Proceedings. Paper presented at 2018 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2018, Houston, United States, 14 May 2018 through 17 May 2018 (pp. 1-6). IEEE
Open this publication in new window or tab >>Evaluation of a CO2 sensitive thermopile with an integrated multilayered infrared absorber by using a long path length NDIR platform
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2018 (English)In: I2MTC 2018 - 2018 IEEE International Instrumentation and Measurement Technology Conference: Discovering New Horizons in Instrumentation and Measurement, Proceedings, IEEE, 2018, p. 1-6Conference paper, Published paper (Refereed)
Abstract [en]

In this work, a mid-infrared-sensitive thermopile detector was evaluated for carbon dioxide gas. The thermopile has an integrated absorber structure that has more than 95% absorption for the wavelength range of 3.3-5.5 μm. For the measurement of carbon dioxide, the detector was initially assembled on a small printed circuit board holder and then installed in a long path length non-dispersive infrared platform. The measurement setup was calibrated by exposing the detector to carbon dioxide of known concentrations (from 50 ppm to 1,300 ppm) and measuring the corresponding voltage response of the detector. The measured voltage values allowed us to calculate the calibration constant for this detector. This was followed by a verification process using a concentration of 500 ppm (which was not used in the calibration) and a known value of 1,300 ppm. The verification results matched with real values, demonstrating that the sensor can be used for highly sensitive and accurate carbon dioxide measurements at concentrations from a few ppm level up to 1,300 ppm. Above this level, additional calibration is needed. 

Place, publisher, year, edition, pages
IEEE, 2018
Keywords
Carbon dioxide gas measurement, LPL-NDIR sensor, Thermopile detector
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-34564 (URN)10.1109/I2MTC.2018.8409758 (DOI)2-s2.0-85050722432 (Scopus ID)9781538622223 (ISBN)
Conference
2018 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2018, Houston, United States, 14 May 2018 through 17 May 2018
Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2018-10-15Bibliographically approved
Niskanen, I., Sutinen, V., Thungström, G. & Räty, J. (2018). Image Information Obtained Using a Charge-Coupled Device (CCD) Camera During an Immersion Liquid Evaporation Process for Measuring the Refractive Index of Solid Particles. Applied Spectroscopy, 72(6), 908-912
Open this publication in new window or tab >>Image Information Obtained Using a Charge-Coupled Device (CCD) Camera During an Immersion Liquid Evaporation Process for Measuring the Refractive Index of Solid Particles
2018 (English)In: Applied Spectroscopy, ISSN 0003-7028, E-ISSN 1943-3530, Vol. 72, no 6, p. 908-912Article in journal (Refereed) Published
Abstract [en]

The refractive index is a fundamental physical property of a medium, which can be used for the identification and purity issues of all media. Here we describe a refractive index measurement technique to determine simultaneously the refractive index of different solid particles by monitoring the transmittance of light from a suspension using a charge-coupled device (CCD) camera. An important feature of the measurement is the liquid evaporation process for the refractive index matching of the solid particle and the immersion liquid; this was realized by using a pair of volatile and non-volatile immersion liquids. In this study, refractive indices of calcium fluoride (CaF2) and barium fluoride (BaF2) were determined using the proposed method.

Keywords
BaF2, barium fluoride, CaF2, calcium fluoride, CCD camera, charge-coupled device camera, evaporation, image immersion liquid method, liquid mixture, Refractive index
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-33666 (URN)10.1177/0003702818756660 (DOI)000434314700010 ()29336586 (PubMedID)2-s2.0-85046036635 (Scopus ID)
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2019-03-15Bibliographically approved
Thungström, G., Lundgren, A., Menk, R. H., Westerberg, L. & Fröjdh, C. (2018). Investigation of radiation hardness in lateral position sensitive detector, irradiated with 13.5 nm photons. Paper presented at 20th International Workshop on Radiation Imaging Detectors, Sundsvall, SWEDEN, JUN 24-28, 2018. Journal of Instrumentation, 13, Article ID C12015.
Open this publication in new window or tab >>Investigation of radiation hardness in lateral position sensitive detector, irradiated with 13.5 nm photons
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2018 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 13, article id C12015Article in journal (Refereed) Published
Abstract [en]

Radiation hardness measurements have been done by irradiating lateral position sensitive (Si) detectors (LPSD) with 93 eV photons. Three different passivation layers have been investigated, SiO2, oxynitride and deposited 4 nm titanium-layer, on p in n-substrate LPSD and deposited 4 nm titanium layer on n in p-substrate LPSD. Best radiation hardness for 93 eV photon is obtained by using a 4 nm titanium layer. Only a slight decrease in response can be seen in the p in n-substrate LPSD. The best radiation hardness is achieved by using the n in p-substrate LPSD, which show no significant decrease in response. Scanning after irradiation with 93 eV gives only a variation in response of 0.26% in the surrounding area of exposure. No decrease in response can be detected during the scan. Test with a 108 eV photon beam gives an increased variation in response of 0.7%, caused by the shallower absorption in Si.

Keywords
Materials for solid-state detectors, Photon detectors for UV, visible and IR photons (vacuum), Radiation-hard detectors
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-35398 (URN)10.1088/1748-0221/13/12/C12015 (DOI)000453207800002 ()2-s2.0-85059896139 (Scopus ID)
Conference
20th International Workshop on Radiation Imaging Detectors, Sundsvall, SWEDEN, JUN 24-28, 2018
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-03-15Bibliographically approved
Forsberg, V., Andersson, H., Engholm, M., Thungström, G., Zhang, R., Hummelgård, M., . . . Norgren, M. (2018). Photodetector of multilayer exfoliated MoS2 deposited on polyimide films. In: : . Paper presented at 20th International Workshop on Radiation Imaging Detectors, Sundsvall, 24-28 June, 2018.
Open this publication in new window or tab >>Photodetector of multilayer exfoliated MoS2 deposited on polyimide films
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

We fabricated a photodetector based on multilayer molybdenum disulfide (MoS2) by micromechanical cleavage of a molybdenite crystal using a polyimide film. We deposited 40 nm of gold by vacuum sputtering and copper tape was used for the contacts.  Without any surface treatment, we achieved high responsivity at different incident optical power. The calculated responsivity was 23 mA/W of incident optical power in the range between 400 and 800 nm. For the responsivity measurement it was estimated that MoS2 have a bandgap of 1.6 eV, which lies between monolayer and multilayer films. The thickness of the MoS2 thin film was determined by Raman spectroscopy evaluating the difference between the in plane  and out of plane  Raman modes. The measurement of IV curves indicated Ohmic contacts in respect to the Au regardless of the incident optical power. Our device fabrication was much simpler than previous reported devices and can be used to test the light absorption and luminescence capabilities of exfoliated MoS2.

Keywords
Photodetector, MoS2
National Category
Chemical Engineering Materials Engineering Physical Sciences
Identifiers
urn:nbn:se:miun:diva-34035 (URN)
Conference
20th International Workshop on Radiation Imaging Detectors, Sundsvall, 24-28 June, 2018
Funder
Knowledge Foundation, 2600364
Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2018-08-16Bibliographically approved
Gaynullin, B., Bryzgalov, M., Hummelgård, C., Mattsson, C., Rödjegård, H. & Thungström, G. (2017). Pressure characterization and resolution limits' investigation of high accuracy NDIR Methane sensor for environmental applications. In: : . Paper presented at 14th International Workshop on Advanced Infrared Technology and Applications, AITA 2017, Québec City, Canada, September 27-29, 2017.
Open this publication in new window or tab >>Pressure characterization and resolution limits' investigation of high accuracy NDIR Methane sensor for environmental applications
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2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-32634 (URN)
Conference
14th International Workshop on Advanced Infrared Technology and Applications, AITA 2017, Québec City, Canada, September 27-29, 2017
Available from: 2018-01-02 Created: 2018-01-02 Last updated: 2018-01-03Bibliographically approved
Ashraf, S., Mattsson, C. & Thungström, G. (2016). Fabrication of a mid-Ir sensitive thermopile detector. In: Proceedings of IEEE Sensors: . Paper presented at 15th IEEE Sensors Conference, SENSORS 2016; Convention Center at the Caribe Royale HotelOrlando; United States; 30 October 2016 through 2 November 2016. IEEE, Article ID 7808481.
Open this publication in new window or tab >>Fabrication of a mid-Ir sensitive thermopile detector
2016 (English)In: Proceedings of IEEE Sensors, IEEE, 2016, article id 7808481Conference paper, Published paper (Refereed)
Abstract [en]

This paper reports on the integration of a multilayered mid-infrared absorber structure into a SU-8 epoxy membrane-based thermopile detector. The absorber structure was designed and simulated using transfer matrix theory. The fabricated absorber structures were characterized through Fourier transform infrared spectroscopy. The structure shows an absorption of more than 95% in the wavelength range of 3.30pm–5pm for simulations, and 3.2pm–5.47pm for FTIR measurements. The complete fabrication process of a thermopile detector including the integration of a multilayered absorber structure has been presented. A MEMS based infrared emitter was used to characterize the fabricated detector. The serial resistance was measured to 315 kΩ and the responsivity was calculated to 57.5 Vmm2W−1 at a wavelength of 4.26pm. The time constant for the fabricated detector was estimated to around 21ms.

Place, publisher, year, edition, pages
IEEE, 2016
Series
IEEE Sensors, ISSN 1930-0395
Keywords
Detectors, Voltage measurement, Fabrication, Absorption, Electrical resistance measurement, Wavelength measurement, Resistance
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-29547 (URN)10.1109/ICSENS.2016.7808481 (DOI)000399395700076 ()2-s2.0-85011003061 (Scopus ID)STC (Local ID)978-1-4799-8287-5 (ISBN)STC (Archive number)STC (OAI)
Conference
15th IEEE Sensors Conference, SENSORS 2016; Convention Center at the Caribe Royale HotelOrlando; United States; 30 October 2016 through 2 November 2016
Available from: 2017-01-17 Created: 2016-12-13 Last updated: 2018-10-15Bibliographically approved
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