liu.seSearch for publications in DiVA
Change search
Refine search result
1234567 151 - 200 of 655
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 151.
    Dannetun, Helen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Wilzén, L.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Petersson, L.-G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The study of alcohol induced hydrogen permeation in a catalytic membrane reactor1996In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 357, p. 804-808Article in journal (Refereed)
    Abstract [en]

    We have studied dehydrogenation and subsequent permeation of hydrogen from some small alcohols and hydrocarbons over a 20 μm thin Pd membrane at temperatures between 523 and 623 K. It is only for the smaller alcohols that significant amounts of hydrogen permeate the membrane. An addition of oxygen in the alcohol supply is needed to prevent a slow quenching of the permeation. The ratio of oxygen to alcohol is critical. For the right balance between methanol and oxygen permeation is very effective, and comparable to permeation caused by pure hydrogen. Studies of CH3OD and C2H5OD further show that the permeation is dependent on the hydrogen origin, i.e. the methyl and hydroxyl hydrogen have different reaction pathways and permeation probabilities.

  • 152.
    Dannetun, Helen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wilzén, Lars
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Johansson, M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Petersson, L.-G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hydrogen production from methanol over a palladium membrane1996Conference paper (Refereed)
  • 153.
    Dannetun, Helen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wilzén, Lars
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Petersson, L.-G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Alcohol dehydrogenation by a palladium membrane1995Conference paper (Refereed)
  • 154.
    Dannetun, Helen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wilzén, Lars
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Petersson, L.-G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Dehydrogenation of alcohols on a palladium membrane1995Conference paper (Refereed)
  • 155.
    Darmastuti, Zhafira
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    SiCFET gassensors: theory, developent, and applications to flue gas cleaning processes  in power plants2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Environmental and health concerns lead to stricter regulations on power plant emission. Sensors play an important role, not only as part of the process control to ensure that the effluent stays under the regulated values, but also to increase the pollution removal efficiency and to decrease the reagent consumption.

    Previous studies, on the use of SiC based Field Effect Transistors (FET) as NH3 sensors in Tekniska Verken power plants and as CO sensors for the control of the domestic boilers, have shown promising results. Moreover, these sensors can withstand high temperature operation and are considerably cheaper than most conventional sensors used in power plants. The price of the sensors enable the installation of multiple sensors in one flue gas duct section, which lead to better monitoring of the flue gas uniformity. Based on that argument, this study is performed to determine whether it is possible to expand the possible application of SiC-FET sensors for the detection of other pollutants emitted by power plants. This thesis reports the characterization and performance testing of SiC-FET sensors towards other selected air pollutants: H2S, methanol as a product of CO2 hydrogenation, and SO2.

    The study is performed by I-V characterization of the sensors toward the test gas in different background gases and studies of the detection mechanism. Detection mechanism studies include DRIFT spectroscopy, mass spectroscopy, and theoretical study of the surface reaction with Density Functional Theory (DFT).

    Ir-gate SiC-FET sensors at 350oC show a very high sensitivity to H2S. The large response reduces the possibility of cross-sensitivity from other gases. Pt-gate sensors offer very fast response with decent response magnitude at 200oC for methanol. The presence of oxygen improves the response to methanol, which is favorable for the leak detection application. Besides oxygen, the influence of hydrogen, propene, and water vapor is also observed in the experiment with methanol. The detection mechanism and different  sensing behavior of Pt and Ir gates are illustrated with model reaction mechanisms on the surface of the metals. Sensor characterization has been performed for SO2 with several catalytic metal gates: Pt, Ir, Cu, and Au. The results suggest that a single sensor with any of Pt, Ir, Cu, and Au gates is able to detect the presence of SO2 in the air or nitrogen background. However, they are unable to measure different SO2 concentration. Moreover, the response level to SO2 is so small, that it will probably disappear if there is any other gas present in the mixture.

    List of papers
    1. SiC based field effect transistor for H2S detection
    Open this publication in new window or tab >>SiC based field effect transistor for H2S detection
    Show others...
    2011 (English)In: Proc. IEEE Sensors 2011, Limerick, Ireland, October 28-31, IEEE , 2011, p. 770-773Conference paper, Published paper (Refereed)
    Abstract [en]

    Experimental characterization and quantum chemical calculations were performed to evaluate the performance of a SiC based Field Effect Transistors with Pt and Ir gates as H2S sensors. The sensors were tested against various concentrations of H2S gas at the operating temperature between 150 and 350 °C. It was observed that Ir was very sensitive and selective to H2S at 350 °C. This phenomenon was studied further by comparing the reaction energy when H2S is exposed to Pt and Ir with density functional theory (DFT) calculations.

    Place, publisher, year, edition, pages
    IEEE, 2011
    Series
    IEEE Sensors, ISSN 1930-0395 ; 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-73850 (URN)10.1109/ICSENS.2011.6127411 (DOI)978-1-4244-9290-9 (ISBN)
    Conference
    IEEE Sensors 2011, 28-31 October, Limerick, Ireland
    Available from: 2012-01-14 Created: 2012-01-14 Last updated: 2015-03-09
    2. SiC-FET methanol sensors for process control and leakage detection
    Open this publication in new window or tab >>SiC-FET methanol sensors for process control and leakage detection
    Show others...
    2013 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 187, no SI, p. 553-562Article in journal (Refereed) Published
    Abstract [en]

    Two types of SiC based field effect transistor sensors, with Pt or Ir gate, were tested to detect methanol in the concentration range of 0–1600 ppm for both process control and leak detection applications. The methanol response was investigated both with and without oxygen, since the process control might be considered as oxygen free application, while the sensor is operated in air during leak detection. Pt sensors offered very fast response with appreciably high response magnitude at 200 °C, while Ir sensors showed both higher response and response time up to 300 °C, but this decreased considerably at 350 °C. Cross sensitivity effect in presence of oxygen, hydrogen, propene and water vapor was also investigated. The presence of oxygen improved the response of both sensors, which is favorable for the leak detection application. Hydrogen had a large influence on the methanol response of both sensors, propene had a negligible influence, while water vapor changed direction of the methanol response for the Pt sensor. The detection mechanism and different sensing behavior of Pt and Ir gate sensors were discussed in the light of model reaction mechanisms derived from hybrid density-functional theory quantum-chemical calculations.

    Keywords
    SiC-FET sensor, methanol, quantum-chemical calculation, Pt, Ir, gas sensor
    National Category
    Engineering and Technology Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-85636 (URN)10.1016/j.snb.2013.04.019 (DOI)000324298300081 ()
    Available from: 2012-11-26 Created: 2012-11-26 Last updated: 2018-09-14Bibliographically approved
  • 156.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Larsson, Mikael
    Alstom Power, Sweden.
    Lindqvist, Niclas
    Alstom Power, Sweden.
    SiC based field effect transistor for H2S detection2011In: Proc. IEEE Sensors 2011, Limerick, Ireland, October 28-31, IEEE , 2011, p. 770-773Conference paper (Refereed)
    Abstract [en]

    Experimental characterization and quantum chemical calculations were performed to evaluate the performance of a SiC based Field Effect Transistors with Pt and Ir gates as H2S sensors. The sensors were tested against various concentrations of H2S gas at the operating temperature between 150 and 350 °C. It was observed that Ir was very sensitive and selective to H2S at 350 °C. This phenomenon was studied further by comparing the reaction energy when H2S is exposed to Pt and Ir with density functional theory (DFT) calculations.

  • 157.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Bhattacharyya, P.
    Dept. of Electronics and Telecommunication Engineering, Bengal Engineering and Science University, India.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Kanungo, Jayita
    IC Design & Fabrication Centre, Dept. of Electronics & Telecommunications Engineering, Jadavpur University, Kolkata, India.
    Basu, Sukumar
    IC Design & Fabrication Centre, Dept. of Electronics & Telecommunications Engineering, Jadavpur University, Kolkata, India.
    Käll, Per-Olov
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Inorganic Chemistry.
    Ojamäe, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Chemistry.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    SiC-FET methanol sensors for process control and leakage detection2013In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 187, no SI, p. 553-562Article in journal (Refereed)
    Abstract [en]

    Two types of SiC based field effect transistor sensors, with Pt or Ir gate, were tested to detect methanol in the concentration range of 0–1600 ppm for both process control and leak detection applications. The methanol response was investigated both with and without oxygen, since the process control might be considered as oxygen free application, while the sensor is operated in air during leak detection. Pt sensors offered very fast response with appreciably high response magnitude at 200 °C, while Ir sensors showed both higher response and response time up to 300 °C, but this decreased considerably at 350 °C. Cross sensitivity effect in presence of oxygen, hydrogen, propene and water vapor was also investigated. The presence of oxygen improved the response of both sensors, which is favorable for the leak detection application. Hydrogen had a large influence on the methanol response of both sensors, propene had a negligible influence, while water vapor changed direction of the methanol response for the Pt sensor. The detection mechanism and different sensing behavior of Pt and Ir gate sensors were discussed in the light of model reaction mechanisms derived from hybrid density-functional theory quantum-chemical calculations.

  • 158.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Pearce, Ruth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    The influence of gate bias and structure on the CO sensing performance of SiC based field effect sensors2011In: Proceedings of IEEE Sensors Conference, 2011, p. 133-136Conference paper (Refereed)
    Abstract [en]

    SiC based Field Effect Transistor gas sensors with Pt as gate material have previously been shown to exhibit a binary CO response, sharply switching between a small and a large value with increasing CO or decreasing O2 concentration or temperature. In this study Pt gates with different structures have been fabricated by dc magnetron sputtering at different argon pressures and subjected to various CO/O2 mixtures under various temperatures and gate bias conditions. The influence of gate bias and gate structure on the CO response switch point has been investigated. The results suggest that the more porous the gate material or smaller the bias, the lower the temperature or higher the CO concentration required in order to induce the transition between a small and a large response towards CO. These trends are suggested to reflect the adsorption, spill-over, and reaction characteristics of oxygen chemisorbed to the Pt and insulator surfaces.

  • 159.
    Davide, F.
    et al.
    IEEE, Telecom Italia S.p.A, D1 Forraazione, I-00148 Rome, Italy.
    Andersson, Mike
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Holmberg, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Chaotic chemical sensing2002In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 2, no 6, p. 656-662Article in journal (Refereed)
    Abstract [en]

    In this paper, we have examined the behavior of a chaotic circuit where one of the components has been replaced by a chemical sensor. The response of the sensor is manifested as a change in the attractor of the circuit. Furthermore, with a proper operating point, a small response of the sensor causes a change in the attractor of the circuit within a time much shorter than the normally defined response time of the sensor. This technique unites sensors and data processing as one combined unit in a unique fashion. © 2002 IEEE.

  • 160. Di Natale, C
    et al.
    Filippini, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Alimelli, A.
    Pennazza, G.
    Santonico, M.
    D´Amico, A.
    Paolesse, R.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ubiquitos chemical sensing and optical imaging for ubiquitos environments2007In: ICRA 2007 Workshop-Robotic olfaction towards real applications,2007, 2007Conference paper (Refereed)
  • 161.
    Di Natale, C
    et al.
    University Roma Tor Vergata.
    Martinelli, E
    University Roma Tor Vergata.
    Paolesse, R
    University Roma Tor Vergata.
    DAmico, A
    University Roma Tor Vergata.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    An artificial olfaction system based on the optical imaging of a large array of chemical reporters2009In: SENSORS AND ACTUATORS B-CHEMICAL, ISSN 0925-4005, Vol. 142, no 2, p. 412-417Article in journal (Refereed)
    Abstract [en]

    Electronic noses are object of research since more than two decades; nonetheless. the analogies between natural and olfaction systems are still limited to the selectivity properties of the receptors. The implementation of more sophisticated features such as the large number of receptors and the glomeruli layer have been hampered by technical difficulties related to the management of a large number of contemporaneous signals. As demonstrated in the past, optical imaging is a read-out technique for sensors development that can provide large sensor arrays. In this paper an artificial olfaction system based on the imaging of a continuous layer of chemical indicators is illustrated. The system incorporates an array of thousands of sensors, corresponding to the pixels of the image. The choice of Computer Screen Photoassisted Technology as a platform for optical interrogation of the sensing layer allows for the definition of a strategy for an automatic definition of a glomeruli layer based on the classification of the optical fingerprints of the image pixels. Chemical indicators were dissolved into a polymeric matrix providing the further property of odor diffusion mimicking the functions of the olfactory mucosa. The system has been tested in a simple experiment and data have been treated applying a lateral inhibition to the glomeruli layer resulting in a dynamic pattern resembling that observed in natural olfaction.

  • 162.
    Di, Natale C.
    et al.
    Di Natale, C., Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy.
    Martinelli, E.
    Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy.
    Paolesse, R.
    Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome, Italy.
    D'Amico, A.
    Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy.
    Filippini, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    An experimental biomimetic platform for artificial olfaction2008In: PLoS ONE, ISSN 1932-6203, Vol. 3, no 9Article in journal (Refereed)
    Abstract [en]

    Artificial olfactory systems have been studied for the last two decades mainly from the point of view of the features of olfactory neuron receptor fields. Other fundamental olfaction properties have only been episodically considered in artificial systems. As a result, current artificial olfactory systems are mostly intended as instruments and are of poor benefit for biologists who may need tools to model and test olfactory models. Herewith, we show how a simple experimental approach can be used to account for several phenomena observed in olfaction. An artificial epithelium is formed as a disordered distributed layer of broadly selective color indicators dispersed in a transparent polymer layer. The whole epithelium is probed with colored light, imaged with a digital camera and the olfactory response upon exposure to an odor is the change of the multispectral image. The pixels are treated as olfactory receptor neurons, whose optical properties are used to build a convergence classifier into a number of mathematically defined artificial glomeruli. A non-homogenous exposure of the test structure to the odours gives rise to a time and spatial dependence of the response of the different glomeruli strikingly similar to patterns observed in the olfactory bulb. The model seems to mimick both the formation of glomeruli, the zonal nature of olfactory epithelium, and the spatio-temporal signal patterns at the glomeruli level. This platform is able to provide a readily available test vehicle for chemists developing optical indicators for chemical sensing purposes and for biologists to test models of olfactory system organization. © 2008 Di Natale et al.

  • 163. Di Natale, C.
    et al.
    Paolesse, R.
    Alimelli, A.
    Filippini, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    D´Amico, A.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    A novel gas-chromatography based sensor array: CSPT imaging of time resolved diffusion of gases in porphyrins embedded polymers2007In: IEEE Sensors 2007,2007, 2007Conference paper (Refereed)
  • 164. Di Natale, C.
    et al.
    Pennazza, G.
    Santonico, M.
    Alimelli, A.
    Paolesse, R.
    D.Amico, A.
    Filippini, Daniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    A hybrid sensor array based on optical and mass transducers2006Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Poster på konferensen "Eurosensors XX", Göteborg, Sweden, 17-20 sept.

  • 165.
    Di Natale, Corrado
    et al.
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    Buchholt, Kristina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Martinelli, E
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    Paolesse, Roberto
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    D´Amico, Arnaldo
    University of Rome Tor Vergata, via del Politecnico 1, 00133 Roma, Italy.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Investigation of the selectivity properties of metalloporphyrines self-assembled-monolayers on QMB and FET transducers2006In: Proc Eurosensors XX, 2006, article id T1A-P11Conference paper (Refereed)
    Abstract [en]

    Progresses of synthetic chemistry methodologies have allowed the preparation of a great variety of artificial receptors that are particularly appealing for chemical sensor development. In this paper, we investigate and compare the properties of gas sensors based on two types of devices, quartz microbalances (QMBs) and field effect transistors (FETs), which give the means to exploit the molecular recognition events occurring in non-conductive sensing layers formed by a thiol-modified cobalt tetraphenylporphyrin (CoTPPSH). Since QMB is sensitive to mass and FET is sensitive to electric dipoles, the resulting sensors are expected to exhibit different sensitivities and selectivities, although both based on the same sensing layer. In particular we show that the high sensitivity of CoTPPSH-coated FETs towards CO and NO is a consequence of the significant CoTPPSH electric dipole change after the gas coordination to the metal centre.

  • 166.
    Di Natale, Corrado
    et al.
    University Roma Tor Vergata.
    Buchholt, Kristina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Martinelli, Eugenio
    University Roma Tor Vergata.
    Paolesse, Roberto
    University Roma Tor Vergata.
    Pomarico, Giuseppe
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    DAmico, Arnaldo
    University Roma Tor Vergata.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Investigation of quartz microbalance and ChemFET transduction of molecular recognition events in a metalloporphyrin film2009In: Sensors and actuators. B, Chemical, ISSN 0925-4005, Vol. 135, no 2, p. 560-567Article in journal (Refereed)
    Abstract [en]

    Progresses of synthetic chemistry methodologies have allowed the preparation of a great variety of artificial receptors that are particularly appealing for chemical sensor development. In this paper, we investigate and compare the properties of gas sensors based on two types of devices, quartz microbalances (QMBs) and field effect transistors (FETs), which give the means to exploit the molecular recognition events occurring in non-conductive sensing layers formed by a thiol-modified cobalt tetraphenylporphyrin (CoTPPSH). Since QMB is sensitive to mass and FET is sensitive to electric dipoles, the resulting sensors are expected to exhibit different sensitivities and selectivities, although both based on the same sensing layer. In particular we show that the high sensitivity of CoTPPSH-coated FETs towards CO and NO is a consequence of the significant CoTPPSH electric dipole change after the gas coordination to the metal centre.

  • 167.
    Di Natale, Corrado
    et al.
    Univ Roma Tor Vergata, Dept Elect Engn, I-00133 Rome, Italy.
    Paolesse, Roberto
    Univ Roma Tor Vergata, Dept Chem Sci and Technol, I-00133 Rome, Italy.
    DAmico, Arnaldo
    Univ Roma Tor Vergata, Dept Elect Engn, I-00133 Rome, Italy.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Multi-transduction of molecular recognition events in metalloporphyrin layers2009In: Journal of Porphyrins and Phthalocyanines, ISSN 1088-4246, E-ISSN 1099-1409, Vol. 13, no 11, p. 1123-1128Article in journal (Refereed)
    Abstract [en]

    Besides the design and synthesis of appropriate molecular recognition systems, the development of chemical sensors requires a careful selection of the transducer to allow conversion of the chemical interaction into an exploitable electric signal. Metalloporphyrins, which are characterized by manifold of interactions of different strength and selectivity, provide a good example of the complexity of such an issue. In this paper, an example of the different ways to capture interactions occurring in a metalloporphyrin layer is presented. In particular, the properties of mass ( quartz microbalance) and surface potential transducers (field effect transistor) are illustrated. Results suggest that field effect transistors are more suitable to preserve the interactions magnitude scale than to maintain the original selectivity of the molecular recognition system.

  • 168.
    Di Natale, Corrado
    et al.
    University Roma Tor Vergata.
    Santonico, Marco
    University Roma Tor Vergata.
    Paolesse, Roberto
    University Roma Tor Vergata.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    DAmico, Arnaldo
    University Roma Tor Vergata.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Evaluation of the performance of sensors based on optical imaging of a chemically sensitive layer2010In: ANALYTICAL AND BIOANALYTICAL CHEMISTRY, ISSN 1618-2642, Vol. 397, no 2, p. 613-621Article in journal (Refereed)
    Abstract [en]

    Interest in the use of the optical properties of chemical indicators is growing steadily. Among the optical methods that can be used to capture changes in sensing layers, those producing images of large-area devices are particularly interesting for chemical sensor array development. Until now, few studies addressed the characterization of image sensors from the point of view of their chemical sensor application. In this paper, a method to evaluate such performance is proposed. It is based on the simultaneous measurement of absorption events in a metalloporphyrin layer with an image sensor and a quartz microbalance (QMB). Exploiting the well-known behaviour of QMB, comparison of signals enables estimation of the minimum amount of absorbed molecules that the image sensor can detect. Results indicate that at the single pixel level a standard image sensor (for example a webcam) can easily detect femtomoles of absorbed molecules. It should therefore be possible to design sensor arrays in which the pixels of images of large-area sensing layers are regarded as individual chemical sensors providing a ready and simple method for large sensor array development.

  • 169.
    Dini, Francesca
    et al.
    University Roma Tor Vergata.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Paolesse, Roberto
    University Roma Tor Vergata.
    DAmico, Arnaldo
    University Roma Tor Vergata.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Di Natale, Corrado
    University Roma Tor Vergata.
    Polymers with embedded chemical indicators as an artificial olfactory mucosa2010In: ANALYST, ISSN 0003-2654, Vol. 135, no 6, p. 1245-1252Article in journal (Refereed)
    Abstract [en]

    Physiological investigations suggest that the olfactory mucosa probably plays an ancillary role in the recognition of odours introducing a sort of chromatographic separation that, together with the zonal distribution of olfactory receptors, gives place to selective spatio-temporal response patterns. It has been recently suggested that this behaviour may be simulated by chemical sensors embedded in continuous polymer layers. In this paper, in analogy to the biology of olfaction, a simple and compact platform able to separate and detect gases and vapours on the basis of their diffusion properties is proposed. In such a system, broadly selective colour indicators, such as metalloporphyrins, are embedded in continuous layers of polymers with different sorption properties. The exposure to various alcohols and amines shows that the porphyrins are mainly responsible for the recognition of the molecular family, while the occurring spatio-temporal signal patterns make possible the identification of the individual chemical species.

  • 170.
    Dini, Francesca
    et al.
    University of Roma Tor Vergata, Italy .
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Paolesse, Roberto
    University of Roma Tor Vergata, Italy .
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Di Natale, Corrado
    University of Roma Tor Vergata, Italy .
    Computer screen assisted digital photography2013In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 179, no SI, p. 46-53Article in journal (Refereed)
    Abstract [en]

    The computer screen photo-assisted techniques (CSPT) have been developed during the last 10 years through an extensive collaboration between University of Rome "Tor Vergata" and Linkoping University in Sweden. CSPT has thus evolved into a concept we now call computer screen assisted digital photography, yielding detailed information about the interaction between color indicators and (volatile) analytes. In the present paper, we give a brief summary of the CSPT concept and its connection to digital photography. We concentrate, however, on the most recent results, which were obtained by using most of the degrees of freedom offered by a computer screen as a light source and a digital (web) camera as a detector. Thus, we describe in detail recent experiments on cotton yarns impregnated with color indicators for volatile organic molecules. The interaction between the color indicators and molecules, like trimethylamine, was investigated by CSPT in high dynamic imaging together with a background noise limiting algorithm. It is shown that the simultaneous use of the last two additions to the CSPT concept considerably enhances the chemical sensing ability of CSPT. It is concluded that the collaboration between Rome and Linkoping has generated a useful platform for further developments of chemical analysis with a ubiquitous instrumentation, a (computer) screen and a web camera. This technique is aimed at facilitating the assembly of opto-chemical sensors with evident benefits in the reduction of cost of sensor systems and in an increased integrability with the existent telecommunication infrastructures.

  • 171.
    Dini, Francesca
    et al.
    University Roma Tor Vergata.
    Martinelli, Eugenio
    University Roma Tor Vergata.
    Paolesse, Roberto
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Filippini, Daniel
    University Roma Tor Vergata.
    DAmico, Arnaldo
    University Roma Tor Vergata.
    Lundstroem, Ingernar
    University Roma Tor Vergata.
    Di Natale, Corrado
    University Roma Tor Vergata.
    Polymer matrices effects on the sensitivity and the selectivity of optical chemical sensors2011In: SENSORS AND ACTUATORS B-CHEMICAL, ISSN 0925-4005, Vol. 154, no 2, p. 220-225Article in journal (Refereed)
    Abstract [en]

    Polymers are commonly used in optical chemical sensors as inert supports for indicator dyes keeping the molecules apart to allow for exposure to analytes and to maintain the peculiar optical properties of the sensitive dyes. However, the partitioning properties of polymers may play a significant role in determining the sensitivity of the sensors. Herewith, the properties of a single dye blended with different polymers have been studied through optical absorbance changes elicited by the exposure to organic vapors. Results show that the partitioning properties of polymers modulate the response of the dye and confer a combinatorial selectivity to the system, allowing for the recognition of vapors.

  • 172.
    Dini, Francesca
    et al.
    University of Roma Tor Vergata.
    Martinelli, Eugenio
    University of Roma Tor Vergata.
    Paolesse, Roberto
    University of Roma Tor Vergata.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Schild, Detlev
    University of Gottingen.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Di Natale, Corrado
    University of Roma Tor Vergata.
    Data processing for image-based chemical sensors: unsupervised region of interest selection and background noise compensation2012In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 402, no 2, p. 823-832Article in journal (Refereed)
    Abstract [en]

    Natural olfaction suggests that numerous replicas of small sensors can achieve large sensitivity. This concept of sensor redundancy can be exploited by use of optical chemical sensors whose use of image sensors enables the simultaneous measurement of several spatially distributed indicators. Digital image sensors split the framed scene into hundreds of thousands of pixels each corresponding to a portion of the sensing layer. The signal from each pixel can be regarded as an independent sensor, which leads to a highly redundant sensor array. Such redundancy can eventually be exploited to increase the signal-to-noise ratio. In this paper we report an algorithm for reduction of the noise of pixel signals. For this purpose, the algorithm processes the output of groups of pixels whose signals share the same time behavior, as is the case for signals related to the same indicator. To define these groups of pixels, unsupervised clustering, based on classification of the indicator colors, is proposed here. This approach to signal processing is tested in experiments on the chemical sensitivity of replicas of eight indicators spotted on to a plastic substrate. Results show that the groups of pixels can be defined independently of the geometrical arrangement of the sensing spots, and substantial improvement of the signal-to-noise ratio is obtained, enabling the detection of volatile compounds at any location on the distributed sensing layer.

  • 173.
    Dini, Francesca
    et al.
    University Roma Tor Vergata.
    Martinelli, Eugenio
    University Roma Tor Vergata.
    Pomarico, Giuseppe
    University Roma Tor Vergata.
    Paolesse, Roberto
    University Roma Tor Vergata.
    Monti, Donato
    University Roma Tor Vergata.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    DAmico, Arnaldo
    University Roma Tor Vergata.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Di Natale , Corrado
    University Roma Tor Vergata.
    Chemical sensitivity of self-assembled porphyrin nano-aggregates2009In: NANOTECHNOLOGY, ISSN 0957-4484 , Vol. 20, no 5, p. 055502-Article in journal (Refereed)
    Abstract [en]

    Nanostructured molecular assemblies may provide additional sensing properties not found in other arrangements of the same basic constituents. Among three-dimensional structures, nanotubes are particularly appealing for applications as chemical sensors, because of the potential inclusion of different guests inside the cavity or the induced modification of the skeletal interaction after analyte binding. Porphyrins are a class of compounds characterized by brilliant sensing properties, appearing also in non-ordered solid-state aggregates. In recent years, it was reported that aggregation of oppositely charged porphyrins led to the formation of self-assembled nanotubes and in this paper their sensing properties, both in solution and in the solid state, have been investigated.

    The interactions of porphyrin nanotubes with guest molecules have been monitored by following the changes in their UV-vis spectra. The results obtained have been exploited to build up a sensing platform based on a computer screen as a light source and a digital camera as detector.

    Porphyrin nanostructures exhibited an enhanced sensitivity to different compounds with respect to those shown by single porphyrin subunits. The reason for the increased sensitivity may be likely found in an additional sensing mechanism related to the modulation of the strength of the forces that keep the supramolecular ensemble together.

  • 174.
    Dyreklev, Peter
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Berggren, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology. null.
    Andersson, Mats R.
    Chalmers Tekniska Högskola.
    Wennerström, Olof
    Chalmers Tekniska Högskola.
    Hjertberg, Thomas
    Chalmers Tekniska Högskola.
    Polarized electroluminescence from an oriented substituted polythiophene in a light emitting diode1995In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 7, no 1, p. 43-45Article in journal (Refereed)
    Abstract [en]

    Polarized light sources based on stretch-oriented conjugated polymers are reported. The devices, based on poly 3(4-octylphenyl)-2,2′-bithiophene, show an external quantum efficiency of 0.1% and are produced using a very simple method which may be easily extended to other polymers. The fabrication of the devices is described and factors such as the emission and spectral differences parallel and prependicular to the stretching direction discussed.

  • 175.
    Ekeroth, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Borgh, Annika
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry . Linköping University, The Institute of Technology.
    Electrochemical Evaluation of the Interfacial Capacitance upon Phosphorylation of Amino Acid Analogue Molecular Films2001In: Analytical Chemistry, ISSN 0003-2700, Vol. 73, no 18, p. 4463-4468Article in journal (Refereed)
    Abstract [en]

    An approach based on electrochemistry to differentiate between phosphorylated and nonphosphorylated amino acid analogues adsorbed on gold is presented. Analogues of serine, threonine, and tyrosine, containing thiohexadecyl headgroups, were synthesized and assembled on gold, and the surface capacitance was evaluated using electrochemical impedance spectroscopy. A procedure for deprotection of tert-butyl phosphate protecting groups, on the monolayer, is also described. Characterizations of the assembled analogues by cyclic voltammetry, infrared spectroscopy, and ellipsometry are used to confirm the insulating properties of the monolayers and the outcome of surface modifications. The results from cyclic voltammetry show good insulating properties for the monolayers even after phosphate deprotection. The infrared measurements reveal well-ordered monolayers, and the thickness from ellipsometry is in good agreement with expectations from molecular modeling. The impedance experiments show a capacitance increase up to 0.6 μF/cm2 as phosphate groups are introduced. The results in this study indicate the possibility of using a surface chemical and impedance spectroscopy approach to detect the kinase/phosphatase activity and kinetics involved in phosphorylation reactions.

  • 176.
    Ekeroth, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Monitoring the interfacial capacitance at self-assembled phosphate monolayers on gold electrodes upon interaction with calcium and magnesium2002In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 74, no 9, p. 1979-1985Article in journal (Refereed)
    Abstract [en]

    Electrochemical impedance spectroscopy has been used to evaluate the change in interracial capacitance upon calcium and magnesium coordination to a phosphate-modified electrode. The phosphate electrode was prepared via immobilization of phosphorylated, thiol-containing, serine analogues onto gold. Upon subjection to calcium and magnesium, a substantial drop in capacitance was observed. Magnesium displayed the largest influence on the capacitance: a 27% capacitance drop was observed upon introduction of a 1 mM solution of magnesium ions. The lowered capacitance is a result of a change in the potential and charge distribution at the film/electrolyte interface as the cations coordinate to the phosphate groups. Moreover, the relationship between electrode potential and capacitance has been investigated and reveals a significant difference between monovalent and divalent cations. As complementary information, infrared reflection absorption spectra of the phosphorylated monolayer having different counterions are presented. The results reported in this paper indicate that the phosphorylated amino acid analogue monolayers could be used in investigations of the biochemically important coordination of calcium and magnesium to phosphates and phosphorylated amino acids.

  • 177. Elisabeth, Abom A.
    et al.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Twesten, R.D.
    Center for Microanalysis of Materials, Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 618 01, United States.
    Properties of combined TiN and Pt thin films applied to gas sensing2002In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 20, no 3, p. 667-673Article in journal (Refereed)
    Abstract [en]

    The effect of Pt in the proximity of TiN with respect to the oxidation behavior was addressed. TiN was grown at two different temperatures that are known to produce films with varying porosity. Pt was used as the catalytic metal and either deposited on top of the TiN film grown at 400°C or co-sputtered in a reactive atmosphere of Ar and N2 at the two different deposition temperatures. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray diffraction, Auger electron spectroscopy (AES), and x-ray photoemission spectroscopy (XPS), and the gas response of the sensor to hydrogen, ammonia, propene, and acetaldehyde was measured. Aging studies were also carried out for a period of one month. Overall, significant results were obtained.

  • 178.
    Enander, Karin
    et al.
    Division of Organic Chemistry, Uppsala University.
    Aili, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Division of Organic Chemistry, Department of Chemistry, BMC, Uppsala University, Uppsala, Sweden.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Alpha-helix-inducing dimerization of synthetic polypeptide scaffolds on gold2005In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 6, p. 2480-2487Article in journal (Refereed)
    Abstract [en]

    Designed, synthetic polypeptides that assemble into four-helix bundles upon dimerization in solution were studied with respect to folding on planar gold surfaces. A model system with controllable dimerization properties was employed, consisting of negatively and positively charged peptides. Circular dichroism spectroscopy and surface plasmon resonance based measurements showed that at neutral pH, the peptides were able to form heterodimers in solution, but unfavorable electrostatic interactions prevented the formation of homodimers. The dimerization propensity was found to be both pH- and buffer-dependent. A series of infrared absorption−reflection spectroscopy experiments of the polypeptides attached to planar gold surfaces revealed that if the negatively charged peptide was immobilized from a loading solution where it was folded, its structure was retained on the surface provided it had a cysteine residue available for anchoring to gold. If it was immobilized as random coil, it remained unstructured on the surface but was able to fold through heterodimerization if subsequently exposed to a positively charged polypeptide. When the positively charged peptide was immobilized as random coil, heterodimerization could not be induced, probably because of high-affinity interactions between the charged primary amine groups and the gold surface. These observations are intended to pave the way for future engineering of functional surfaces based on polypeptide scaffolds where folding is known to be crucial for function.

  • 179.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Andersson, Linda
    Göteborg universitet.
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Designed, folded polypeptides for bioanalytical purposes - molecular scaffolds that combine recognition and reporting2001In: 4th International Conference on Structural Molecular Biology,2001, 2001Conference paper (Other academic)
    Abstract [en]

      

  • 180.
    Enander, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Andersson, Linda
    Department of Organic Chemistry Göteborg University.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Designed, folded polypeptide scaffolds that combine key biosensing events of recognition and reporting2002In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, no 9, p. 3120-3123Article in journal (Refereed)
    Abstract [en]

    No abstract available.

  • 181.
    Enander, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    A versatile polypeptide platform for integrated recognition and reporting: affinity arrays for protein-ligand interaction analysis2004In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 10, no 10, p. 2375-2385Article in journal (Refereed)
    Abstract [en]

    A molecular platform for protein detection and quantification is reported in which recognition has been integrated with direct monitoring of target-protein binding. The platform is based on a versatile 42-residue helix–loop–helix polypeptide that dimerizes to form four-helix bundles and allows site-selective modification with recognition and reporter elements on the side chains of individually addressable lysine residues. The well-characterized interaction between the model target-protein carbonic anhydrase and its inhibitor benzenesulfonamide was used for a proof-of-concept demonstration. An affinity array was designed where benzenesulfonamide derivatives with aliphatic or oligoglycine spacers and a fluorescent dansyl reporter group were introduced into the scaffold. The affinities of the array members for human carbonic anhydrase II (HCAII) were determined by titration with the target protein and were found to be highly affected by the properties of the spacers (dissociation constant Kd=0.02–3 μM). The affinity of HCAII for acetazolamide (Kd=4 nM) was determined in a competition experiment with one of the benzenesulfonamide array members to address the possibility of screening substance libraries for new target-protein binders. Also, successful affinity discrimination between different carbonic anhydrase isozymes highlighted the possibility of performing future isoform-expression profiling. Our platform is predicted to become a flexible tool for a variety of biosensor and protein-microarray applications within biochemistry, diagnostics and pharmaceutical chemistry.

  • 182.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    De novo designed helix-loop-helix polypeptides - a structure-function-based design strategy for microarray and biosensor applications2003In: 1st World Congress on Synthetic Receptors,2003, 2003Conference paper (Refereed)
  • 183.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Designed, folded polypeptides as functional units in biosensor applications2002In: 18:e Organikerdagarna,2002, 2002Conference paper (Other academic)
  • 184.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Löfdahl, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Designed, folded polypeptides as functional units in surface-based biosensors - versatile scaffolds connecting recognition and reporting2002In: Europtrode VI,2002, 2002Conference paper (Refereed)
  • 185.
    Enander, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Löfdahl, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Baltzer, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Helix-loop-helix polypeptides as scaffolds for designed biosensing surfaces2002In: 6th World Congress on Biosensors,2002, 2002Conference paper (Other academic)
  • 186.
    Engquist, Isak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lestelius, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hydrogen Bond Interaction between Self-Assembled Monolayers and Adsorbed Water Molecules and Its Implications for Cluster Formation1995In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 99, no 39, p. 14198-14200Article in journal (Refereed)
    Abstract [en]

    Infrared spectroscopy is used to investigate the adsorption of D2O onto self-assembled monolayers of methyl 16-mercaptohexadecanoate on gold. The D2O molecules are shown to interact with the carbonyl oxygens of the monolayer, forming hydrogen bonds and causing a structural rearrangement of the CO2CH3 terminal group. The number of hydrogen bonds decreases as the amorphous-like, essentially flat (two-dimensional) ice overlayer that forms at 100 K changes into polycrystalline-like ice upon annealing at 140 K. This decrease is a consequence of the formation of three-dimensional ice clusters, which leaves a large fraction of the monolayer surface bare.

  • 187.
    Engquist, Isak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lestelius, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Microscopic wettability of ester- and acetate-terminated self-assembled monolayers1997In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 13, no 15, p. 4003-4012Article in journal (Refereed)
    Abstract [en]

    Four different carbonyl-containing self-assembled monolayers (SAMs) of alkanethiolates on gold were studied to assess the impact of the functional group Linked to the carbonyl upon its hydrogen bond accepting capability. These SAMs (HS(CH2)(16)O(C=O)-X,X = CH3, CF3, or C6H5, and HS(CH2)(15)(C=O)OCH3) were thoroughly characterized with contact angle measurements, single wavelength ellipsometry, and infrared reflection-absorption spectroscopy (IRAS) prior to the studies of interaction with D2O. The first three monolayer compounds were introduced by reacting hydroxyl-terminated SAMs (HS(CH2)(16)OH) with either acetyl chloride, trifluoroacetic anhydride, or benzoyl chloride. The behavior of D2O ice on the SAMs was investigated at 100 K with IRAS and temperature programmed desorption (TPD). On all monolayers the D2O molecules were shown to interact with the carbonyl oxygen. The degree of interaction depended upon the termination of the thiol, where the size, structure, and electronegativity of the terminating groups in the molecules comprising the monolayer were found to be important factors. Indications of interaction with the C-O-C oxygen were seen for all compounds, as well as weak interaction between water molecules and the CF3 group of one of the investigated SAMs. Common behavior for all four monolayers with an adsorbed D2O overlayer was a decrease in the number of hydrogen bonds to the substrate when the overlayer was annealed from amorphous ice at 100 K to polycrystalline-like ice at 140 K. The spectral changes accompanying the structural transition were consistent with a change from a mainly flat overlayer to condensed three-dimensional clusters. The bulk-to-surface molecular ratio of adsorbed ice clusters could be assessed by IRAS and correlated to macroscopic wetting properties. Our results infer that microscopic ice clusters on these SAMs qualitatively mimic the shape of macroscopic water drops on the same SAMs. Results of TPD measurements are also consistent with this view.

  • 188.
    Engquist, Isak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    D2O ice on controlled wettability self-assembled alkanethiolate monolayers: Cluster formation and substrate-adsorbate interaction1996In: JOURNAL OF PHYSICAL CHEMISTRY, ISSN 0022-3654, Vol. 100, no 51, p. 20089-20096Article in journal (Refereed)
    Abstract [en]

    Infrared reflection-absorption spectroscopy is used to investigate thin (1-200 Angstrom average thickness) overlayers of D2O ice deposited in ultrahigh vacuum on controlled wettability self-assembled monolayers. The monolayers were derived from mixed solutions of HS(CH2)(15)CH3 and HS(CH2)(16)OH, making it possible to examine the whole range of samples from f(OH) = 0.0 to f(OH) 1.0, where f(OH) denotes the molar fraction of OH-terminated thiols in the preparation solution. This paper focuses on the interaction between the ice and the monolayer. It is shown that water molecules do not penetrate into the monolayer but that two types of interaction with the chain-terminating groups occur: hydrogen bond formation with surface hydroxyls and weak dipole-dipole interaction with surface methyls. For surfaces with f(OH) less than 0.3, the latter interaction causes the free OD mode, normally observed at 2729 cm(-1), to shift to 2704 cm(-1), thereby providing a spectral signature feature whose intensity is directly proportional to the relative area of the ice/monolayer interface. Quantitative analysis of the infrared spectra suggests that ice clusters are essentially flat on surfaces with 0.6 less than f(OH) less than 1.0 and become more droplet-like for decreasing f(OH) below 0.6. On f(OH) = 0.0 surfaces, the microscopic clusters display high contact angles (similar to 120 degrees), and full surface coverage does not occur until the average overlayer thickness is 150-200 Angstrom.

  • 189.
    Engquist, Isak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Temperature-programmed desorption and infrared studies of D2O ice on self-assembled alkanethiolate monolayers: influence of substrate wettability1995In: JOURNAL OF PHYSICAL CHEMISTRY, ISSN 0022-3654, Vol. 99, no 32, p. 12257-12267Article in journal (Refereed)
    Abstract [en]

    This paper examines the relationship between the thermal desorption of thin overlayers of condensed D2O ice and the wettability properties of the supporting substrate surface. Mixed self-assembled monolayers (SAMs) on gold with controlled chemical composition and wettability (-0.4 less than cos theta less than 1.0, where theta represents the static contact angle with water) derived from HS(CH2)(16)OH and HS(CH2)(15)CH3 were used as model surfaces. The D2O ice overlayers were prepared on these substrates by dosing of 0.1-30 langmuirs of D2O in ultrahigh vacuum at 80-120 K and characterized with temperature-programmed desorption (TPD). Infrared reflection-absorption spectroscopy (IRAS) was also used to characterize the structural progressions within the overlayers during the course of the TPD experiments, as well as at selected temperatures before and after annealing of the overlayer structure. The IRAS data show that amorphous-like ice is formed at sufficiently low temperatures (less than or equal to 100 K) on all mixed SAMs, regardless of their wettability. A structural transition of the D2O ice from amorphous-like to polycrystalline-like is observed above 100 K. The exact onset of the transition is strongly dependent on the wettability and varies from about 110 K on the extreme hydrophobic (CH3) substrate to 145-150 K on the hydrophilic (OH) substrate. On the most hydrophilic substrates, the strong hydrogen bond interaction with surface hydroxyls prevents completion of the structural transition before desorption of the D2O overlayer. This type of pinning of the D2O molecules to the substrate surface is most likely responsible for the sharp increase in desorption energy of similar to 0.2 kcal/mol which is seen at cos theta approximate to 0.6, a value defining the hydrophilicity limit above which, for our set of experimental parameters, the transition is no longer completed. The TPD data also support a model of the D2O overlayer as forming clusters of very different shape depending on substrate wettability-flat, two-dimensional clusters on hydrophilic SAMs and dropletlike, three-dimensional clusters on hydrophobic SAMs.

  • 190.
    Engquist, Isak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Parikh, A.N.
    Pennsylvania State University.
    Allara, D. L.
    Pennsylvania State University.
    Infrared characterization of amorphous and polycrystalline D2O ice on controlled wettability self-assembled alkanethiolate monolayers1997In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 106, no 8, p. 3038-3048Article in journal (Refereed)
    Abstract [en]

    Infrared reflection-absorption spectroscopy has been used to characterize thin overlayers (1-200 Angstrom) of D2O ice deposited in UHV onto a set of self-assembled alkanethiolate monolayers (SAMs) of controlled wettabilities on gold. The SAMs were prepared from a series of controlled composition, mixed solutions of HS(CH2)(15)CH3 and HS(CH2)(16)OH, making it possible to investigate the whole wettability range from theta approximate to 0 degrees to theta=112 degrees, where theta is the static contact angle with water. Dosing of D2O and infrared measurements were carried out at selected sample temperatures between 82 and 150 K. Experimental spectra of ice overlayers recorded below 100 K on all SAM substrates are in good agreement with simulated reflection-absorption spectra, derived from the optical constants of amorphous ice. This agreement allows accurate film thickness determination. In contrast, lack of correspondence in spectral signature is noted between the spectra of annealed films and simulated polycrystalline (or amorphous) ice spectra. We interpret this discrepancy to suggest that significant substrate-induced differences between thin overlayers and bulk ice persist in the latter case. Spectral indications of ice-substrate interaction are also seen for amorphous ice, and are especially prominent in the case of highly hydrophobic (pure CH3-terminated, theta=112 degrees) substrates. In this case the substrate effect extends up to an average film thickness (150-200 Angstrom) corresponding to similar to 50 ice monolayers, in contrast to highly hydrophilic OH-terminated substrate, where the substrate effects appear to vanish beyond similar to 5 monolayers (15-20 Angstrom average thickness). Annealing of thin ice overlayers (2-3 monolayers) clearly demonstrates a strong correlation between the onset as well as progression of the transition from amorphous to polycrystalline ice and the exact substrate wettability or chemical composition. The data further suggest the existence of metastable intermediate forms, that are neither purely amorphous nor polycrystalline. We discuss these observations in terms of substrate-overlayer interaction. A tentative phase diagram summarizing these results is presented. (C) 1997 American Institute of Physics.

  • 191.
    Enquist, F.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    The fabrication of amorphous SiO2 substrates suitable for transmission electron microscopy studies of ultrathin polycrystalline films1986In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 145, no 1, p. 99-104Article in journal (Refereed)
    Abstract [en]

    A method to produce SiO2 transmission electron microscopy substrates by means of silicon micromachining is described. The substrate consists of an SiO2 window 50–200 nm thick suspended in a silicon frame. It was developed to enable the study of ultrathin porous gate metals grown on the same substrate as in the device studied. The thin film to be studied can be vapour phase deposited directly onto the substrate and then without any further manipulations inserted into the transmission electron microscope.

  • 192.
    Ericsson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Bui, Lan
    Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Controlled Orientation and Covalent Attachment of Proteins on Biosensor Surfaces by Chelation Assisted Photoimmobilization2013Manuscript (preprint) (Other academic)
    Abstract [en]

    This report presents a novel method for uniform orientation and covalent attachment of proteins to sensing surfaces, termed Chelation Assisted Photoimmobilization (CAP). Alkanethiols terminated with either nitrilotriacetic acid (NTA), benzophenone (BP) or oligo(ethylene glycol) were synthesized and mixed self-assembled monolayers (SAMs) were prepared on gold and thoroughly characterized by infrared reflection absorption spectroscopy (IRAS), ellipsometry and contact angle goniometry. In the process of CAP, NTA chelates Ni2+ and the complex coordinates a His-tagged ligand in an oriented assembly. The ligand is then photoimmobilized via BP, which forms covalent bonds upon UV light activation. The CAP concept was demonstrated using human IgG-Fc modified with C-terminal hexahistidine tags (His-IgGFc) as the ligand and protein A as the analyte.

    In the development of affinity biosensors, uniform orientation of ligand molecules where all analyte binding sites are accessible is often preferred to random orientation. In order to monitor the effect of ligand orientation on analyte response, the ligand-analyte interaction was quantified by surface plasmon resonance analysis, both in the case of CAP and when the ligand was attached by conventional amine coupling on surfaces presenting NTA. Responses were adjusted for differences in ligand immobilization level using IRAS. The normalized analyte response with randomly oriented ligand was 2.5 times higher than that with ligand immobilized by CAP, probably due to molecular crowding effects on the surface and the fact that His-IgGFc is bivalent for protein A. This is a reminder that many other factors than orientation alone may play a decisive role in analyte binding on biosensor surfaces.

  • 193.
    Ericsson, Emma M
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Bui, Lan
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Controlled orientation and covalent attachment of proteins on biosensor surfaces by Chelation Assisted Photoimmobilization2013Conference paper (Other academic)
    Abstract [en]

    In the context of surface chemistry for affinity biosensor chips, it is widely accepted that uniform orientation of the immobilized recognition element (ligand) is preferred over random orientation. However, this assumption has often been based on studies where differences in ligand immobilization level have not been taken into account. In this contribution, we present a novel two-step method for homogenous orientation and covalent attachment of proteins to sensing surfaces, called Chelation Assisted Photoimmobilization (CAP). Careful quantification of the effect of ligand orientation on analyte responses was performed by comparing this strategy to immobilization by conventional amine coupling.

     In CAP, the chelation agent is nitrilotriacetic acid (NTA) which chelates Ni2+. A His-tagged ligand forms an oriented assembly when binding Ni2+-NTA and is then covalently bound to the surface via photolabile benzophenone (BP), which attacks C-H bonds upon UV light activation. We relied on a surface chemistry based on self-assembled monolayers (SAMs) of oligo(ethylene glycol) (OEG)-containing alkanethiolates on gold. Alkanethiols terminated with either NTA, BP or OEG were synthesized and mixed SAMs were characterized by infrared reflection absorption spectroscopy (IRAS), ellipsometry and contact angle goniometry. IRAS was also used to quantify ligand immobilization levels obtained either by CAP or by amine coupling via the carboxyl groups of an NTA-presenting surface. The model ligand was human IgG-Fc modified with a C-terminal 6xHis-tag and the analyte was Protein A. The ligand-analyte interaction was quantified by a surface plasmon resonance biosensor.

     Analyte responses were normalized with respect to the ligand amounts obtained by the two immobilization strategies. Interestingly, the normalized analyte response with randomly oriented ligand was >2 times higher than that with ligand immobilized by CAP. This shows that oriented ligand immobilization is not necessarily a means of increasing the sensitivity of a biosensor. Factors that may influence performance include the valency of the ligand and constraints related to the surface chemistry used for orientation.

  • 194.
    Eriksson, Jens
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Käll, Per-Olov
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lloyd-Spets, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    ZnO nanoparticles or ZnO films: A comparison of the gas sensing capabilities2009In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 137, no 1, p. 94-102Article in journal (Refereed)
    Abstract [en]

    Zinc oxide is an interesting material for bio and chemical sensors. it is a semiconducting metal oxide with potential as an integrated multisensing sensor platform, which simultaneously detects Parameters like change in field effect, mass and Surface resistivity. in this investigation we have used resistive sensor measurements regarding the oxygen gas sensitivity in order to characterize sensing layers based on electrochemically produced ZnO nanoparticles and PE-MOCVD grown ZnO films. Proper annealing procedures were developed in order to get stable sensing properties and the oxygen sensitivity towards operation temperature was investigated. The ZnO nanoparticles showed a considerably increased response to oxygen as compared to the films. Preliminary investigations were also performed regarding the selectivity to other gases present in car exhausts or flue gases.

  • 195.
    Eriksson, Jens
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Pearce, Ruth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Virojanadara, Chariya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gogova, Daniela
    Leibniz Institute of Crystal Growth, Berlin, Germany .
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Yakimova, Rositza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    The influence of substrate morphology on thickness uniformity and unintentional doping of epitaxial graphene on SiC2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 24, p. 241607-Article in journal (Refereed)
    Abstract [en]

    A pivotal issue for the fabrication of electronic devices on epitaxial graphene on SiC is controlling the number of layers and reducing localized thickness inhomogeneities. Of equal importance is to understand what governs the unintentional doping of the graphene from the substrate. The influence of substrate surface topography on these two issues was studied by work function measurements and local surface potential mapping. The carrier concentration and the uniformity of epitaxial graphene samples grown under identical conditions and on substrates of nominally identical orientation were both found to depend strongly on the terrace width of the SiC substrate after growth.

  • 196.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Iqbal, Zafar
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Two measurement modes for mobile phone optical sensing2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 195, p. 63-70Article in journal (Refereed)
    Abstract [en]

    The use of a mobile phone for classification and quantification of liquid samples is described. The screen of the phone is used for controlled illumination and the front side camera for imaging. No additional optical equipment is needed. It is shown that there are different regions of the captured image containing different information about the sample. One region contains light that has been specular reflected at the air-liquid interface and one is dominated by light that has propagated through the liquid. The specular reflected light contains information about the refractive index of the liquid sample whereas the transmitted light contains information about color and absorption. It is found that the specular reflectance increases linearly with increasing refractive index, n, in the range 1.33 less than n less than 1.38, as expected from the Fresnel equations. A change of the refractive index of about 0.004 refractive units can be detected. The transmitted light intensity is well described by the Beer-Lambert law over a large absorption range. Light from the two different areas of the image is used to analyze several types of liquid samples. It is shown that a combination of the two measurement modes improves the classification abilities of the mobile phone.

  • 197.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Salomonsson, Anette
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Briand, Danick
    Institute of Microtechnology, University of Neuchâtel, Neuchâtel, Switzerland.
    Åbom, Elisabeth
    Sapa Heat Transfer, Finspång, Sweden.
    The influence of the insulator surface properties on the hydrogen response of field-effect gas sensors2005In: Journal of Applied Physics, ISSN 0021-8979, Vol. 98, no 3, p. 34903-34908Article in journal (Refereed)
    Abstract [en]

    The hydrogen response of gas-sensitive field-effect devices is mainly due to trapping of atomic hydrogen on the insulator side of the metal-insulator interface of the metal-insulator-semiconductor (MIS) structure. Therefore an influence of the choice of insulator on the hydrogen response properties is expected. We have investigated this influence by producing MIS capacitors with four different insulators; SiO2, Al2O3, Si3N4, and Ta2O5. The results show that the choice of insulator influences the detection limit, the saturation concentration, and the saturation response. Furthermore, there is a strong correlation between the observed saturation response and the oxygen concentration of the insulator surface, as measured by Auger electron spectroscopy, which indicates that the trapping of hydrogen at the interface occurs at the oxygen atoms of the insulator surface. Finally, if the metal film is porous a catalytic oxidation of the insulator surface appears to be facilitated, which can increase the hydrogen response.

  • 198.
    Eriksson, Mats
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Wallin, M
    Byberg, M
    Grönbeck, H
    Skoglundh, Magnus
    Chalmers Tekniska högskola.
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Vibrational analysis of H2 and NH3 adsorption on Pt/SiO2 model sensors2007In: IEEE Sensors,2007, 2007, p. 1315-Conference paper (Refereed)
  • 199.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Winquist, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Bjorklund, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lindgren, David
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Sundgren, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Event Detection in Crisis Management Systems2009In: Procedia Chemistry, ISSN 1876-6196, E-ISSN 1876-6196, Vol. 1, no 1, p. 1055-1058Article in journal (Refereed)
    Abstract [en]

    The EVENT project concerns drinking water surveillance and includes sensors and algorithms that detect anomalies in the drinking water properties, communication of the evaluated sensor data to a crises management system and presentation of information that is relevant for the end users of the crises management system. We have chosen to focus on a sensor technique based on an "electronic tongue", since this robust type of non-selective sensor, can detect a plurality of anomalies without the need of a specific sensor for each type of event. Measurements of natural variations and contamination events are presented and discussed.

  • 200.
    Eriksson, Therese
    et al.
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Svensson, Samuel
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Andersson, Rolf
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Role of ginsenosides and quercetin in anterograde transport of melanosomesManuscript (preprint) (Other academic)
    Abstract [en]

    Panax ginseng is a traditional herb that has been used in the Orient for several thousands of years as a tonic and restorative. Active components of ginseng include ginsenosides, polysaccharides, flavonoids, polyacetylenes, peptides, vitamins, phenols and enzymes, of which the ginsenosides are considered to be the major bioactive constituents. In spite of extensive use, the exact mechanisms of ginseng and its components are still unknown. In the present study we use melanophores from Xenopus laevis to investigate the effects of Panax ginseng extract G115, ginsenosides and the flavonoid quercetin on pigment organelle transport and signalling. Through coordinated transport of their black pigmented granules (melanosomes), melanophores are capable of fast colour changes. The movement is regulated by changes in cyclic adenosine 3’:5’-monophosphate (cAMP) concentration, where a high or low level induce anterograde (dispersion) or retrograde (aggregation) transport respectively, leaving a dark or light cell. Previously we have shown that Panax ginseng induces dispersion of melanosomes. Here, ginsenoside Rc and Rd and the flavonoid quercetin are shown to stimulate an anterograde transport of pigment organelles. When Rc or Rd and quercetin were combined, a significant synergistic increase in dispersion could be seen. Protein kinase C (PKC) inhibitor Myristoylated EGF-R Fragment (651-658) (M-EGF) decreased the anterograde movement stimulated by ginseng and ginsenoside Rc and Rd. We also demonstrate that ginseng, but not ginsenosides or quercetin, induce a concentration-dependent activation of 44/42-mitogen activated protein kinase (MAPK). PKC-inhibition did not affect the MAPK-activation, suggesting a role for PKC in the ginseng- and ginsenoside-induced anterograde transport but not in the activation of MAPK.

1234567 151 - 200 of 655
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf