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  • 301.
    Inoue, Hirofumi
    et al.
    Kyushu University.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Yuasa, Masayoshi
    Kyushu University.
    Kida, Tetsuya
    Kyushu University.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Shimanoe, Kengo
    Kyushu University.
    CO2 Sensor Combining an MISiC Capacitor and a Binary Carbonate2011In: ELECTROCHEMICAL AND SOLID STATE LETTERS, ISSN 1099-0062, Vol. 14, no 1, p. J4-J7Article in journal (Refereed)
    Abstract [en]

    A solid-state CO2 sensor device using a metal-insulator-silicon carbide (MISiC) capacitor combined with a Li2CO3-BaCO3 auxiliary layer was fabricated and tested for its basic sensing properties. The MISiC-based CO2 sensor attached with the carbonate showed typical capacitance-voltage (C-V) properties in air at 400 degrees C, and the sensor device responded well to changes in CO2 concentration in air at 400 degrees C. The sensor signals were directly proportional to the logarithm of CO2 concentration. The results suggested that an electrochemical reaction of CO2 occurred at the interface between the carbonate layer and the electrode, causing the applied voltage to shift in response to CO2.

  • 302.
    Iqbal, Zafar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bjorklund, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Colorimetric analysis of water and sand samples performed on a mobile phone2011In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 84, no 4, p. 1118-1123Article in journal (Refereed)
    Abstract [en]

    Analysis of water and sand samples was done by reflectance measurements using a mobile phone. The phone’s screen served as light source and front view camera as detector. Reflected intensities for white, red, green and blue colors were used to do principal component analysis for classification of several compounds and their concentrations in the water. Classification of iron (III), chromium (VI) and sodium salt of humic acid was obtained using reflected intensities from blue and green light for concentrations 2-10 mg/l. Analysis of As(III) from 25-400 μg/l based on reflection of red light was performed utilizing the bleaching reaction of tincture of iodine containing starch. Enhanced sensitivity to low concentrations of arsenic was obtained by adding reflected intensities from white light to the analysis. Model colored sand samples representing discoloration caused by the presence of arsenic in groundwater were also analyzed.

  • 303.
    Iqbal, Zafar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Bjorklund, Robert B.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Assessment of a mobile phone for use as a spectroscopic analytical tool for foods and beverages2011In: International journal of food science & technology, ISSN 0950-5423, E-ISSN 1365-2621, Vol. 46, no 11, p. 2428-2436Article in journal (Refereed)
    Abstract [en]

    A mobile phone was used to perform optical analyses of foods and beverages. The phone’s screen served as illumination source and front view camera recorded images. Reflected intensities were used to discriminate among the different samples analysed by principal component analysis. Samples studied illustrated the technique’s potential analytical capabilities with respect to adulteration and authenticity. Three coloured additives (red, green and blue) in the concentration range 2-10 mg/l in a lemon lime beverage were discriminated. Adulteration by up to 25% water of milk with 3% fat content was detected with an estimated detection limit of about 3% water. Changes occurring on a green onion surface over a 48 h aging period at room temperature were monitored. Five different cuts from lamb carcasses weighing 9 and 14 kg were classified by the method. Considerable additional work with regard to sampling, data treatment and quantifying results is necessary before the goal of using the technique as a point of purchase analytical tool can be realised.

  • 304.
    Iqbal, Zafar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Classification and quantitative optical analysis of liquid and solid samples using a mobile phone as illumination source and detector2013In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 185, p. 354-362Article in journal (Refereed)
    Abstract [en]

    A mobile phone has been used both as illumination source and image detector for quantitative optical analysis of colored liquid samples (4 different colorants) and solid samples (printed color patterns, plastic beads and colored sand grains). Even though the measurement conditions were far from ideal, because the light source was strongly polychromatic and the illumination was not a collimated light beam with homogeneous light intensity, a logarithmic concentration dependence, in accordance with the Beer-Lambert law, described the data of the colored liquids quite well. By utilizing blue-blue (420-510 nm), green-green (480-590 nm) and red-red (575-695 nm) illumination/detection combinations, each sample could be assigned a unique color signature for classification that agreed with reference absorbance spectra measured with a spectrometer. Quantification of validation samples within a few percent of the actual values was achieved. Also the long-term repeatability of the measurements was investigated and was surprisingly good for such a simple system. Analysis of the colored solid samples was more complex with results being dependent on the morphology and colorimetric properties of the samples.

  • 305.
    Iqbal, Zafar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Optical sensing with a mobile phone applied to liquid solutions2012Manuscript (preprint) (Other academic)
    Abstract [en]

    The use of a mobile phone with a front side camera for the classification of liquid samples is described. The classification is based on the observation that there are different regions of the image captured by the mobile camera, one containing specular reflected light and one due to diffuse reflected light with transmission through the liquid. The specular reflected light contains information about the refractive index of the liquid sample whereas the diffuse light contains information about the color and absorption properties of the liquid. The information in the specular light is first elucidated. It is found that the reflectance of the region with specular reflected light increases linearly with increasing refractive index, n, in the range 1.33 < n < 1.38 as expected from the Fresnel equations. The information in the specular light is then used together with the previously described diffuse light from another region of the image to analyze several types of liquid samples. It is shown that a combination of the two areas of the image improves the classification abilities of the mobile phone.

  • 306.
    Iqbal, Zafar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spectral Fingerprinting on a Standard Mobile Phone2010In: Journal of Sensors, ISSN 1687-725X, E-ISSN 1687-7268, Vol. 2010, p. 381796-Article in journal (Refereed)
    Abstract [en]

    Spectral fingerprinting of chemical indicators, using computer screens as light sources and web cameras as imaging detectors, is an emerging approach for chemical sensing with the potential to coexist in common consumer electronic devices.The migration of this technique to mobile phones is key to extend this sensing approach to the most ubiquitous and familiar type of instrumentation. Here, we investigate the feasibility and performance of spectral fingerprinting on reference samples using a standard mobile phone as a complete measuring platform, where the screen provides controlled illumination while the front camera is the imaging detector. Key elements for the execution of such experiments are the software design, the definition of the sample layout, the type of alignment between the phone and the sample, and the influence of ambient illumination. This paper demonstrates the feasibility of reflectance fingerprinting on standard mobile phones and identify the operating conditions of the key parameters that produce an adequate evaluation performance.

  • 307.
    Ivarsson, Patrik
    et al.
    Asko Cylinder AB.
    Holmin, Susanne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Hojer, N.-E.
    Höjer, N.-E., Asko Cylinda AB, SE-534 82 Vara, Sweden.
    Krantz-Rülcher, Christina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Winquist, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Discrimination of tea by means of a voltammetric electronic tongue and different applied waveforms2001Conference paper (Other academic)
    Abstract [en]

    A new sensor technology, an electronic tongue based on voltammetry has been developed at Linköping University. Three different metallic working electrodes are used in combination with a set of voltage "pulses", a waveform, to separate different samples. In this paper, three different waveforms are investigated. This is done through a study with nine different teas. Multivariate data analysis ((MVDA), principal component analysis (PCA)) is used to evaluate the data (the recorded current responses). The waveforms are large amplitude pulse voltammetry (LAPV), small amplitude pulse voltammetry (SAPV), and staircase voltammetry. Each method discriminated between the tea samples to some extent, but differently from each other. Best discrimination is achieved when the combination LAPV and staircase are merged together. When SAPV is included in the combination a worse separation is observed. It is clearly the case that more waveforms do not automatically lead to more information. © 2001 Elsevier Science B.V.

  • 308.
    Ivarsson, Patrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering. Asko Cylinder AB.
    Johansson, Madeleine
    Asko Cylinda AB.
    Höjer, Nils-Erik
    Asko Cylinda AB.
    Krantz-Rülcher, Christina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Winquist, Fredrik
    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.
    Supervision of rinses in a washing machine by a voltammetric electronic tongue2005In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 108, no 01-Feb, p. 851-857Article in journal (Refereed)
    Abstract [en]

    A study that investigates if it is possible to discriminate between the different rinses in a household washing machine with a voltammetric electronic tongue is concluded. The voltammetric electronic tongue applies a potential pulse train over two electrodes and measures the produced current. Multivariate data analysis is used to treat the data. In this paper, a simplified electronic tongue, with only 5% of the original current responses, is used. The rinses from 20 machine wash runs with four different prerequisites are investigated. Principal component analysis (PCA) and Soft-independent modelling of class analogy (SIMCA) are used in order to classify the rinses. In PCA, only one of the rinses is classified erroneous, and in SIMCA none of the rinses are classified only to the wrong class, although 38% of the rinses are classitied to more than one class. (c) 2005 Elsevier B.V. All rights reserved.

  • 309.
    Ivarsson, Patrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering. Asko Cylinder AB.
    Kikkawa, Y.
    Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 812-8581, Japan.
    Winquist, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Krantz-Rülcher, Christina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Hojer, N.-E.
    Höjer, N.-E., Asko Cylinda AB, SE-534 82 Vara, Sweden.
    Hayashi, K.
    Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 812-8581, Japan.
    Toko, K.
    Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka 812-8581, Japan.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Comparison of a voltammetric electronic tongue and a lipid membrane taste sensor2001In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 449, no 1-2, p. 59-68Article in journal (Refereed)
    Abstract [en]

    An electronic tongue based on voltammetry and a multichannel lipid membrane taste sensor based on potentiometry are compared using two aqueous examples: detergents and teas. The electronic tongue consists of four electrodes of different metals, a reference electrode and a counter electrode. The measurement principle is based on pulse voltammetry in which current is measured during the change of the amplitude of the applied potential. The taste sensor is based on eight different lipid/polymer membranes. The voltage difference between the electrodes and an Ag/AgCl reference electrode is measured when the current is close to zero. The responses from the two sensors systems are treated separately with multivariate data analysis based on principal component analysis and then merged to examine if further information could be extracted. It is shown that although the two sensor systems are about equal in separation ability in the two cases, extra information can be gained by combination of the two sensor systems. © 2001 Elsevier Science B.V. All rights reserved.

  • 310.
    Ivarsson, Patrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Science & Engineering.
    Krantz-Rülcher, Christina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Winquist, Fredrik
    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 voltammetric electronic tongue2005In: Chemical Senses, ISSN 0379-864X, E-ISSN 1464-3553, Vol. 30, p. I258-i259Article in journal (Refereed)
  • 311.
    Jager, Edwin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    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.
    Microrobots for Micrometer-Size Objects in Aqueous Media: Potential Tools for Single-Cell Manipulation2000In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 288, no 5475, p. 2335-2338Article in journal (Refereed)
    Abstract [en]

    Conducting polymers are excellent materials for actuators that are operated in aqueous media. Microactuators based on polypyrrole-goldbilayers enable large movement of structures attached to theseactuators and are of particular interest for the manipulationof biological objects, such as single cells. A fabrication methodfor creating individually addressable and controllable polypyrrole-goldmicroactuators was developed. With these individually controlledmicroactuators, a micrometer-size manipulator, or microroboticarm, was fabricated. This microrobotic arm can pick up, lift,move, and place micrometer-size objects within an area of about250 micrometers by 100 micrometers, making the microrobot an excellenttool for single-cell manipulation.

  • 312.
    Jager, Edwin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Perpendicular Actuation with Individually Controlled Polymer Microactuators2001In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 13, no 1, p. 76-79Article in journal (Refereed)
    Abstract [en]

    Actuator systems based on conducting polymers, such as polypyrole, with which three-dimensional movement can be controlled, are described. The Figure shows a combination of two such microactuators which are used to “kick” a glass bead across the surface of a silicon wafer. The microfabrication methods used to produce the systems are described and the potential uses, for example microrobotic arms, discussed.

  • 313.
    Jager, Edwin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Smela, Elisabeth
    Risø National Lab, Roskilde.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    On-chip microelectrodes for electrochemistry with moveable PPy bilayer actuators as working electrodes1999In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 56, no 1-2, p. 73-78Article in journal (Refereed)
    Abstract [en]

    We present electrochemical microactuators which have all the electrodes necessary for the actuation—the working, counter, and reference electrodes—on-chip. This is a first step towards an all-polymer system, i.e., a system that does not require a liquid electrolyte. The microactuators' performance was as good as when standard, off-chip counter and reference electrodes were used. Specifically, the speed of actuation was the same. In addition, we obtained a good cyclic voltammogram, although the oxidation and reduction peaks were shifted and some noise was present. Apart from application in an all-polymer system, we will also use these microactuators for studies on the effect of mechanical stimulation of living cells.

  • 314.
    Jager, Edwin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Smela, Elisabeth
    Condensed Matter Department, Risö National Lab.
    Inganäs, Olle
    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.
    Polypyrrole micro actuators1999In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 102, no 1-3, p. 1309-1310Article in journal (Refereed)
    Abstract [en]

    The doping and undoping of conjugated polymers is accompanied by a volume change. This volume change can be used to make micro-actuators. We have built polypyrrole (PPy) gold bilayer structures. The volume change of PPy induces a bending of the bilayer. We have made micro-actuators based on this principle, which have been examined with video-microscopy. Some applications for these microactuators are proposed, including opening and closing boxes for cell biology and nanoliter chemistry and micro-robotics.

  • 315.
    Jager, Edwin W.H.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Immerstrand, Charlotte
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Holmgren Peterson, Kajsa
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Magnusson, Karl-Eric
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    The cell clinic: closable microvials for single cell studies2002In: Biomedical microdevices (Print), ISSN 1387-2176, E-ISSN 1572-8781, Vol. 4, no 3, p. 177-187Article in journal (Refereed)
    Abstract [en]

    We present the development of a cell clinic. This is a micromachined cavity, or microvial, that can be closed with a lid. The lid is activated by two polypyrrole/Au microactuators. Inside the microvials two Au electrodes have been placed in order to perform impedance studies on single or a small number of cells. We report on impedance measurements on Xenopus leavis melanophores. We could measure a change in the impedance upon cell spreading and identify intracellular events such as the aggregation of pigment granules. The electrical data is correlated to optical microscopy.

  • 316.
    Janson, M. S.
    et al.
    Royal Inst Technol KTH, Dept Microelect & Informat Technol, S-16440 Kista, Sweden .
    Linnarsson, M. K.
    Royal Inst Technol KTH, Dept Microelect & Informat Technol, S-16440 Kista, Sweden .
    Hallen, A.
    Royal Inst Technol KTH, Dept Microelect & Informat Technol, S-16440 Kista, Sweden .
    Svensson, B. G.
    Royal Inst Technol KTH, Dept Microelect & Informat Technol, S-16440 Kista, Sweden .
    Achtziger, N.
    Univ Jena, Inst Festkorperphys, D-07743 Jena, Germany .
    Unéus, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Forsberg, Urban
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hydrogen in the wide bandgap semiconductor silicon carbide2004In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T108, p. 99-112Article in journal (Refereed)
    Abstract [en]

    In this paper we give a review of our recent results related to the incorporation of hydrogen (H) in silicon carbide (SiC) and its interaction with acceptor doping atoms and implantation induced defects. Hydrogen is an abundant impurity in the growth of epitaxial SiC since it is present in the precursor gases and since H-2 is used as the carrier gas. High concentrations of hydrogen are indeed incorporated into highly doped p-type epi-layers and it is shown that the main source is the carrier gas. Furthermore, it is revealed that the entire substrate becomes homogeneously filled with hydrogen during growth and that this hydrogen is more thermally stable than that in the epi-layer. Incorporation of hydrogen from an H-2 ambient, at temperatures considerably lower than those used for epitaxy, is also demonstrated in p-type samples coated with a catalytic metal film. This effect is most likely the cause for the increased series resistance observed in p-type SiC Schottky sensor devices using a catalytic metal gate after annealing at 600 degrees C in a H-2 containing ambient. Hydrogen is found to passivate the acceptors Al and B by forming electrically neutral H-acceptor complexes. Unlike in Si and GaAs, the two H-acceptor complexes in SiC exhibit very different dissociation energies, suggesting that the atomic configurations of the complexes are significantly different. The migration of mobile hydrogen in the presence of externally applied, or internal built-in, electric fields further reveals that hydrogen is present as H+ in p-type SiC. Finally, the redistribution and subsequent out-diffusion of low energy implanted H-1 and H-2 is investigated. Two annealing phases for the redistribution are observed, and the activation energies for the processes are extracted.

  • 317. Jansson, E
    et al.
    Kalltorp, M
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, SE-58183 Linkoping, Sweden Univ Gothenburg, Inst Anat & Cell Biol, SE-40530 Gothenburg, Sweden.
    Johansson, A
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Thomsen, P
    Linkoping Univ, Dept Phys & Measurement Technol, Appl Phys Lab, SE-58183 Linkoping, Sweden Univ Gothenburg, Inst Anat & Cell Biol, SE-40530 Gothenburg, Sweden.
    On the formation of fibrous capsule and fluid space around machined and porous blood plasma clot coated titanium2001In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 12, no 10-12, p. 1019-1024Article in journal (Refereed)
    Abstract [en]

    Machined and machined submicron porous titanium, with and without a thin blood plasma coating (100 nm), were implanted for 7 or 28 days in subcutaneous pockets on the back of the rat. After explantation the specimens were analyzed by light microscopy with respect to thickness of the fibrous capsule, the fluid space width between implants and fibrous capsule, and formation of blood vessels. The results at 7 days indicate a thinnest fluid space for the plasma clot coated porous titanium surface, and the spaces vanished at the light microscopic level after 28 days outside all the analyzed surfaces. The thickness of the fibrous capsule increased outside the different surfaces at 7-28 days, and in this respect no significant differences were observed between the different surfaces at any time. Analysis of neovascularization showed that the number of vessels and proportion of vessels in the fibrous capsule increased with time at all surfaces, except machined Ti where the number instead decreased from 7 to 28 days. The average distance between the blood vessels and the fluid space increased with time for all types of surfaces. The results in the present study indicate that the healing process around titanium can be modulated by porosity and thin pre-prepared plasma coatings. (C) Kluwer Academic Publishers.

  • 318. Jansson, E.
    et al.
    Kalltorp, M.
    Källtorp, M., Institute of Anatomy and Cell Biology, Göteborg University, Box 420, SE-405 30 Göteborg, Sweden.
    Thomsen, P.
    Institute of Anatomy and Cell Biology, Göteborg University, Box 420, SE-405 30 Göteborg, Sweden.
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ex vivo PMA-induced respiratory burst and TNF-a secretion elicited from inflammatory cells on machined and porous blood plasma clot-coated titanium2002In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 23, no 13, p. 2803-2815Article in journal (Refereed)
    Abstract [en]

    The release of inflammatory mediators around implants and normal wounds may differ due to the presence of the solid surface. In this study, machined and sub-micron porous titanium implants with and without a 100nm thick blood plasma clot were inserted subcutaneously in rat for 3 or 24h. The cell recruitment to the interfaces, in vivo secretion of TNF-a and the ex vivo PMA-induced production of reactive oxygen species were subsequently investigated. The thin plasma clot coating gave rise to an increased ex vivo PMA-stimulated oxygen radical production by implant-associated cells at both implantation times, and an increased cell recruitment at 24h. The total TNF-a secretion was highest at sham sites and plasma clot-coated porous titanium at 24h. After 24h, the cell-type pattern in the exudate around the porous plasma-coated implant was more similar to that found at sham sites than that adjacent to the non-coated implants. No differences were observed between the machined Ti and the machined sub-micron porous Ti. © 2002 Elsevier Science Ltd. All rights reserved.

  • 319.
    Jansson, Eva
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Adsorption of albumin and IgG to porous and smooth titanium2004In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 35, no 1, p. 45-51Article in journal (Refereed)
    Abstract [en]

    The possibility to load submicrometer porous titanium surfaces with relatively small proteins, albumin and immunoglobulin G (IgG) was investigated. The loading ability is of interest due to the possibility of slow release of molecules from biomaterial surfaces, and may be important for the manipulation of wound healing around prostheses. Iodine-125 (125I) labeled albumin and IgG were adsorbed onto smooth and to porous titanium with a pore diameter of 200-300 nm. The smooth and porous surfaces were divided into three groups: hydrophilic, hydrophobic, or to amine-terminated silane (3- aminopropyltriethoxysilane) that bound proteins via glutaraldehyde. The protein solution pH and protein concentrations were varied, and the adsorption experiments made without or in the presence of calcium and magnesium ions. The adsorbed amounts were quantified with a gamma counter. Two to eleven times more proteins adsorbed onto porous than smooth surfaces and the adsorbed amounts increased with increasing protein concentration (0.1-10 mg/ml) during a constant incubation time. The elutability by sodium dodecyl sulphate (SDS) was incomplete on porous surfaces. © 2004 Elsevier B.V. All rights reserved.

  • 320.
    Jansson, Eva
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    In vitro preparation and ellipsometric characterization of thin blood plasma clot films on silicon2001In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 22, no 13, p. 1803-1808Article in journal (Refereed)
    Abstract [en]

    The wound-healing process around implants differs from that of a normal healing without the inserted material. In this work, the composition of a natural wound surface was mimicked through clotting of a thin human blood plasma film with approximate ellipsometric thickness of 100nm onto differently pretreated silicon surfaces. Their stability was investigated by incubations in sodium dodecyl sulphate (SDS) solutions. The enzymatic clot degradation was induced through addition of human tissue plasminogen activator (t-PA) to the plasma and the surface protein remnants after the degradation were analyzed with polyclonal antibodies. The results show that the plasma films were not SDS resistant on hydrophilic silicon. However, stability was obtained after preparation on hydrophobic silicon or when albumin or fibrinogen was immobilized to silicon before the plasma incubations. Different surfaces bound different polyclonal antibodies after the clot film degradation. The methods indicate a simple means to improve or reestablish a normal tissue inflammatory response around biomaterials. Copyright © 2001 Elsevier Science Ltd.

  • 321. Johansen, K
    et al.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    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 .
    Imaging surface plasmon resonance sensor based on multiple wavelengths: Sensitivity considerations2000In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 71, no 9, p. 3530-3538Article in journal (Refereed)
    Abstract [en]

    A new, multiple wavelength surface plasmon resonance apparatus for imaging applications is presented. It can be used for biosensing, e.g., for monitoring of chemical and biological reactions in real time with label-free molecules. A setup with a fixed incident angle in the Kretschmann configuration with gold as the supporting metal is described, both theoretically and experimentally. Simulations of the sensor response based on independently recorded optical (ellipsometric) data of gold show that the sensitivity for three-dimensional recognition layers (bulk) increases with increasing wavelength. For two-dimensional recognition layers (adlayer) maximum sensitivity is obtained within a limited wavelength range. In this situation, the rejection of bulk disturbances, e.g., emanating from temperature variations, decreases, with increasing wavelength. For imaging surface plasmon resonance the spatial resolution decreases with increasing wavelength. Hence, there is always a compromise between spatial resolution, bulk disturbance rejection, and sensitivity. Most importantly, by simultaneously using multiple wavelengths, it is possible to maintain a high sensitivity and accuracy over a large dynamic range. Furthermore, our simulations show that the sensitivity is independent of the refractive index of the prism. (C) 2000 American Institute of Physics. [S0034-6748(00)02909-9].

  • 322.
    Johansen, Knut
    et al.
    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 .
    Sensitivity deviation: Instrumental linearity errors that influence concentration analyses and kinetic evaluation of biomolecular interactions2000In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 15, no 9-10, p. 503-509Article in journal (Refereed)
    Abstract [en]

    Many scientific instruments utilise multiple element detectors, e.g. CCD's or photodiode arrays, to monitor the change in a position of an optical pattern. For example, instruments for affinity biosensing based on surface plasmon resonance (SPR) or resonant mirror are equipped with such detectors. An important and desired property of these bioanalytical instruments is that the calculation of the movement or change in shape follows the true change. This is often not the case and it may lead to linearity errors, and to sensitivity errors. The sensitivity is normally defined as the slope of the calibration curve. A new parameter is introduced to account for the linearity errors, the sensitivity deviation, defined as the deviation from the undistorted slope of the calibration curve. The linearity error and the sensitivity deviation are intimately related and the sensitivity deviation may lead to misinterpretation of kinetic data, mass transport limitations and concentration analyses. Because the linearity errors are small (e.g. 10 pg/mm2 of biomolecules on the sensor surface) with regard to the dynamic range (e.g. 30 000 pg/mm2), they can be difficult to discover. However, the linearity errors are often not negligible with regard to a typical response (e.g. 0-100 pg/mm2), and may therefore cause serious problems. A method for detecting linearity errors is outlined. Further on, this paper demonstrates how integral linearity errors of less than 1% can result in a sensitivity deviation of 10%, a value that in our opinion cannot be ignored in biospecific interaction analysis (BIA). It should also be stressed out that this phenomenon also occurs in other instruments using array detectors. (C) 2000 Elsevier Science S.A.Many scientific instruments utilize multiple element detectors, e.g. CCD's or photodiode arrays, to monitor the change in a position of an optical pattern. For example, instruments for affinity biosensing based on surface plasmon resonance (SPR) or resonant mirror are equipped with such detectors. An important and desired property of these bioanalytical instruments is that the calculation of the movement or change in shape follows the true change. This is often not the case and it may lead to linearity errors, and to sensitivity errors. The sensitivity is normally defined as the slope of the calibration curve. A new parameter is introduced to account for the linearity errors, the sensitivity deviation, defined as the deviation from the undistorted slope of the calibration curve. The linearity error and the sensitivity deviation are intimately related and the sensitivity deviation may lead to misinterpretation of kinetic data, mass transport limitations and concentration analyses. Because the linearity errors are small (e.g. 10 pg/mm2 of biomolecules on the sensor surface) with regard to the dynamic range (e.g. 30 000 pg/mm2), they can be difficult to discover. However, the linearity errors are often not negligible with regard to a typical response (e.g. 0-100 pg/mm2), and may therefore cause serious problems. A method for detecting linearity errors is outlined. Further on, this paper demonstrates how integral linearity errors of less than 1% can result in a sensitivity deviation of 10%, a value that in our opinion cannot be ignored in biospecific interaction analysis (BIA). It should also be stressed out that this phenomenon also occurs in other instruments using array detectors.

  • 323.
    Johansen, Knut
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Stalberg, R.
    Stålberg, R., Høgskolen i Telemark, Hallvard Eikas plass, 3800 Bø, Norway.
    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 .
    Surface plasmon resonance: Instrumental resolution using photo diode arrays2000In: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 11, no 11, p. 1630-1638Article in journal (Refereed)
    Abstract [en]

    Surface plasmon resonance (SPR) sensors are used to study biomolecular interactions. We have performed a theoretical analysis of a SPR instrument using a convergent beam, a linear detector with various numbers of pixels and various analogue-to-digital converters (ADCs) with a corresponding resolution ranging from 8 to 16 bits. Studies of small molecules at low concentrations or with low affinities are limited by the instrumental set-up, e.g. by the resolution, linearity and noise. The amplitudes of these parameters are highly dependent on the detector, ADC and dip-finding algorithm used. We have studied several dip-finding algorithms, e.g. intensity measurements, second- and third-order polynomial fits and centroid algorithms. Each algorithm used with the ADC and the detector has a resolution associated with it. Some algorithms also have an intrinsic algorithm error that is dependent on the number of pixels and the shape of the dip. A weighted centroid algorithm that has an excellent overall performance is described. If an accuracy of 10-6 refractive index units (RIU) is satisfactory, a 12-bit ADC and a 64-pixel detector are appropriate. Theoretically, by using a 16-bit ADC and a 1024-pixel detector, a resolution of better than 10-9 RIU is obtainable.

  • 324. Johansson, E.
    et al.
    Krantz-Rülcher, Christina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Zhang, B.X.
    Institute of Soil Science, Academica Sinica, Nanjing, China.
    Öberg, Gunilla
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Thematic Studies, Environmental Science.
    Chlorination and biodegradation of lignin2000In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 32, no 7, p. 1029-1032Article in journal (Refereed)
    Abstract [en]

    Recent research has shown that large amounts of high-molecular weight organic chlorine of unknown origin are present in the terrestrial environment. There are indications that an underlying process may be microorganisms which produce reactive chlorine that chemically degrades organic matter and facilitates degradation of recalcitrant organic matter on one hand, and on the other hand causes a formation of organic chlorine. Our aim was to test one part of this hypothesis by investigating whether reactive chlorine facilitates microbial degradation of lignin. Different concentrations of chlorine dioxide were added to the autoclaved lignin suspension. Mycelium of the white-rot fungus P. chrysosporium was used to inoculate flasks with the lignin solutions. The evolution of CO2 was followed during 8 d of continuous measurement. At the end of the experiment the solutions were analyzed for organic chlorine. The amount of CO2 evolved was variable, but the results were repeatedable, addition of chlorine dioxide to the lignin solutions caused an increase in the mineralization by P. chrysosporium that increased with increasing additions of chlorine dioxide. This suggests that exposure of lignin to reactive chlorine enhance its biodegradability. The most likely cause of the observed effect is that the addition of chlorine dioxide initiated a fragmentation and oxidation of the lignin, thus rendering a more easily degraded substrate. However, the results may also be interpreted as if an additional cause to the observed effect is that the chlorination in itself somehow enhanced degradation. The amount of organically-bound chlorine decreased during the incubation, and the decrease was more pronounced with the chlorination of lignin, whereas no change at all was observable in the control batches. This makes it tempting to suggest that P. chrysosporium rather than having an enzyme system just capable of handling the chlorinated compounds, actually has a system that preferentially degrades such compounds. (C) 2000 Elsevier Science Ltd.

  • 325.
    Johansson, Fredrik
    et al.
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Andersson, Tony P. M.
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Faculty of Health Sciences.
    Svensson, Samuel P. S.
    Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
    Is effect of (S;S)-formoterol due to contamination of (R;R)-formoterol?Manuscript (preprint) (Other academic)
    Abstract [en]

    Formoterol is a long acting selective ß2-adrenoceptor (ß2-AR) agonist of the so-called third generation of ß-adrenoceptor agonists. lt also has an onset action comparable to most short acting ß2-AR agonists. Formoterol has two chiral centres making four enantiomers possible. In this study we have examined (R;R)- and (S;S)-formoterol relaxing effect on guinea pig tracheal ring preparations, affinity to human ß2-AR in transfected COS-7 cells and the ability to influence pigment movement in frog melanophores with stable expression of human ß2AR. We also compared single concentration curves versus cumulative concentration curves on guinea pig tracheal preparations. In all three systems the (R;R)-formoterol is the most potent ß2AR agonist compered to (S;S)-formoterol with eudismic ratios ranging from 11 to 75. We also measure and theoretically calculated the effect of (S;S)-formoterol. VVhen the contamination of (R;R)-formoterol was subtracted the (S;S)-formoterol had effect, although approximately 72 times less then (R;R)-formoterol. We conclude that (R;R)-formoterol is the most potent ß2-AR agonist in three different systems and that (S;S)-formoterol posses an ß2-AR effect. We also show that cumulative concentration curves have higher EC50 values compered to single concentration curves and that this might be a consequence of recaptor desensitisation.

  • 326. Johansson, M
    et al.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ekedahl, Lars-Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    An equipment for three-dimensional spatially resolved gas analysis2000In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 71, no 9, p. 3513-3521Article in journal (Refereed)
    Abstract [en]

    The apparatus described is able to measure three-dimensional temperature and partial pressure distributions in gas mixtures with a spatial resolution better than 0.5 mm. The measurements are performed in a well defined laminar gas flow in a duct of rectangular cross section. The gas mixture is sampled locally with a quartz tube orifice leak movable in three dimensions. Mass spectrometry is used for partial pressure measurements. The total pressure in the duct can be regulated in the range 50-760 Torr and the gas temperature can be varied between room temperature and 500 degrees C. The apparatus is primarily designed for studies of the distribution of reactants and products over catalytic surfaces. Because of the well defined gas flow in the duct the partial pressure distributions of reactants and products over the catalytic surface can be calculated with good accuracy. By comparing calculated pressure distributions to measured ones the local reaction rate on the catalytic surface as well as the pressures of reactants and products at the surface can be obtained. As an example it is shown how the hydrogen distribution over a platinum surface exposed to a mixture of hydrogen, oxygen, and argon can be used to calculate the local water formation rate on the platinum surface. (C) 2000 American Institute of Physics. [S0034-6748(00)01409-X].

  • 327.
    Kalantar-zadeh, Kourosh
    et al.
    RMIT University.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Penza, Michele
    ENEA.
    Bhaskaran, Madhu
    RMIT University.
    Sriram, Sharath
    RMIT University.
    Wlodarski, Wojtek
    RMIT University.
    Faraone, Lorenzo
    University Western Australia.
    Matthews, Glenn
    RMIT University.
    Selected Peer-Reviewed Articles from 13th International Meeting on Chemical Sensors (IMCS-13)2011In: Sensor Letters, ISSN 1546-198X, E-ISSN 1546-1971, Vol. 9, no 2, p. 584-586Article in journal (Other academic)
  • 328.
    Kalli, K
    et al.
    University of Cyprus, Cyprus.
    Othonos, A
    University of Cyprus, Cyprus.
    Christofides, C
    University of Cyprus, Cyprus.
    Lloyd Spetz, Anita
    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, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Temperature-induced reflectivity changes and activation of hydrogen sensitive optically thin palladium films on silicon oxide1998In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 69, no 9, p. 3331-3338Article in journal (Refereed)
    Abstract [en]

    The optical properties of several thin metal film palladium-silicon oxide structures are examined at room temperature before and after annealing to 200 degrees C and also at 90 degrees C-in all cases in the presence of hydrogen gas. Multicycling sample activation is shown to occur iii the presence of hydrogen at room temperature with an increase in reflectivity on exposure to hydrogen, in contrast to thicker 80 Angstrom films. The reflectivity change increases with increasing film thickness (1-10 Angstrom). The surface activation at room temperature, before and after annealing to 200 degrees C, is compared with the performance at 90 degrees C, where it is shown that heat treatment strongly influences the behavior of the metal film.

  • 329. Kalltorp, M
    et al.
    Carlen, A
    Thomsen, P
    Olsson, J
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Analysis of rat plasma proteins desorbed from gold and methyl- and hydroxyl-terminated alkane thiols on gold surfaces2000In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 11, no 3, p. 191-199Article in journal (Refereed)
    Abstract [en]

    It is believed that adsorbed blood or plasma components, such as water, peptides, carbohydrates and proteins, determine key events in the concomitant inflammatory tissue response close to implants. The aim of the present study was to develop a procedure for the collection and analysis of minor amounts of proteins bound to solid metal implant surfaces. The combination of a sodium dodecyl sulfate washing method coupled with a polyacylamide gel electrophoretic protein separation technique (SDS-PAGE), Western blot and image analysis enabled the desorption, identification and semiquantification of specific proteins. The analyzed proteins were albumin, immunoglobulin G, fibrinogen and fibronectin. Concentration procedures of proteins were not required with this method despite the small area of the test surfaces. The plasma proteins were adsorbed to pure gold and hydroxylated and methylated gold surfaces, which elicit different tissue responses in vivo and plasma protein adsorption patterns in vitro. The image analysis revealed that the pure gold surfaces adsorbed the largest amount of total and specific proteins. This is in accordance with previous ellipsometry/antibody experiments in vitro. Further, the principles described for the protein analysis can be applied on implant surfaces ex vivo. (C) 2000 Kluwer Academic Publishers.

  • 330. Kalman, E.-L.
    et al.
    Lofvendahl, A.
    Löfvendahl, A., Volvo Car Corporation, 98351 PV 1B, S-405 08, Göteborg, Sweden.
    Winquist, Fredrik
    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 .
    Classification of complex gas mixtures from automotive leather using an electronic nose2000In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 403, no 1-2, p. 31-38Article in journal (Refereed)
    Abstract [en]

    A semiconductor gas sensor array combined with a routine for pattern recognition - a so-called electronic nose - for the detection of gas emissions from the leather used in car compartments is described. The gas sensors are 10 metal oxide semiconductor field effect transistors (MOSFETs) with gates of thin, catalytic metals, and five semiconducting metal oxide sensors. The sensor array data are processed by multivariate means using principal component analysis (PCA) and are shown to give similar and add additional information compared to gas chromatography-mass spectrometry (GC- MS) and a human sensory panel. The total volatile organic compound concentration as measured by GC did not differ between good and bad samples and could therefore not be used as a quality control tool, whilst the electronic nose together with pattern recognition could readily discover the deviating samples with unusual emitting gases. This set-up could be useful in on-line quality monitoring systems to detect anomalies in incoming car interior trim materials.

  • 331. Kalman, E.-L.
    et al.
    Winquist, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lofvendahl, A.
    Löfvendahl, A., Volvo Car Corporation, Department 98351 PV 1B.
    Rudell, B.
    Wass, U.
    Volvo Technological Development Corporation, Department 06700 PVH 38, Gothenburg, Sweden.
    Chemical gas sensors for car exhaust and cabin air monitoring2002In: Indoor + Built Environment, ISSN 1420-326X, E-ISSN 1423-0070, Vol. 11, no 2, p. 105-110Article in journal (Refereed)
    Abstract [en]

    A combination of charcoal and particle filters has previously been shown to reduce effectively the smell of diesel exhaust. In this paper it is shown that the smell of diesel exhaust can successfully be predicted by the concentration of total volatile organic compounds and the concentration of certain carbonyl compounds. Projection to latent structures was utilised for model building. An electronic nose consisting of MOSFET and MOS sensors could less successfully predict the smell, but identified the same filter combination as being most efficient. The car cabin air during urban driving was also monitored, both by the means of MOSFET sensors and by chemiluminescence. The pollution level inside the car is shown to be elevated by about 30% compared to outside the car. A combination filter together with an air inlet sensor switch is shown to reduce the NOx levels inside the car by 30% compared to outside, with the ability to significantly decrease the peak levels. Copyright © 2002 S. Karger AG, Basel.

  • 332.
    Kanungo, Jayita
    et al.
    IC Design & Fabrication Centre, Dept. of Electronics & Telecommunications Engineering, Jadavpur University, Kolkata, India.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Darmastuti, Zhafira
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Basu, Sukumar
    IC Design & Fabrication Centre, Dept. of Electronics & Telecommunications Engineering, Jadavpur University, Kolkata, India.
    Käll, Per-Olov
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. 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.
    Development of SiC-FET methanol sensor2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 160, no 1, p. 72-78Article in journal (Refereed)
    Abstract [en]

    A silicon carbide based field effect transistor (SiC-FET) structure was used for methanol sensing. Due to the chemical stability and wide band gap of SiC, these sensors are suitable for applications over a wide temperature range. Two different catalytic metals, Pt and Ir, were tested as gate contacts for detection of methanol. The sensing properties of both Ir gate and Pt gate SiC-FET sensors were investigated in the concentration range 0.3–5% of methanol in air and in the temperature range 150–350 °C. It was observed that compared to the Ir gate sensor, the Pt gate sensor showed higher sensitivity, faster response and recovery to methanol vapour at comparatively lower temperature, with an optimum around 200 °C. Quantum-chemical calculations were used to investigate the MeOH adsorption and to rationalize the observed non-Langmuir behavior of the response functions. The methanol sensing mechanism of the SiC-FET is discussed.

  • 333.
    Kanungo, Jayita
    et al.
    Jadavpur University IC Design and Fabrication Center, Kolkata, India.
    Basu, Palash K.
    Jadavpur University IC Design and Fabrication Center, Kolkata, India.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Sukumar, Basu
    Jadavpur University IC Design and Fabrication Center, Kolkata, India.
    Detection of Hydrogen by Noble Metal Treated Nanoporous Si and ZnO thin films2011In: Sensors & Transducers Journal, ISSN 2306-8515, E-ISSN 1726-5479, Vol. 10, p. 131-140Article in journal (Refereed)
  • 334.
    Karimian, Najmeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology. Ferdowsi University of Mashhad, Iran.
    Vagin, Mikhail
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hossein Arbab Zavar, Mohammad
    Ferdowsi University of Mashhad, Iran .
    Chamsaz, Mahmoud
    Ferdowsi University of Mashhad, Iran .
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    An ultrasensitive molecularly-imprinted human cardiac troponin sensor2013In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 50, p. 492-498Article in journal (Refereed)
    Abstract [en]

    Cardiac troponin T (TnT) is a highly sensitive cardiac biomarker for myocardial infarction. In this study, the fabrication and characterisation of a novel sensor for human TnT based on a molecularly-imprinted electrosynthesised polymer is reported. A TnT sensitive layer was prepared by electropolymerisation of o-phenylenediamine (o-PD) on a gold electrode in the presence of TnT as a template. To develop the molecularly imprinted polymer (MIP), the template molecules were removed from the modified electrode surface by washing with alkaline ethanol. Electrochemical methods were used to monitor the processes of electropolymerisation, template removal and binding. The imprinted layer was characterised by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The incubation of the MIP-modified electrode with respect to TnT concentration resulted in a suppression of the ferro/ferricyanide redox process. Experimental conditions were optimised and a linear relationship was observed between the peak current of [Fe(CN)(6)](3-)/[Fe (CN)(6)](4-) and the concentration of TnT in buffer over the range 0.009-0.8 ng/mL, with a detection limit of 9 pg/mL. The TnT MIP sensor was shown to have a high affinity to TnT in comparison with nonimprinted polymer (NIP) electrodes in both buffer and blood serum.

  • 335.
    Karlsson, Annika M.
    et al.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Bjuhr, Katarina
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Testorf, Martin
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Öberg, Åke
    Linköping University, Department of Biomedical Engineering, Physiological Measurements. Linköping University, The Institute of Technology.
    Lerner, Ethan
    Bunsen Rush Laboratories, Dallas, TX, USA.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Svensson, Samuel P.S.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Biosensing of opioids using frog melanophores2002In: Biosensors and Bioelectronics, ISSN 0956-5663, Vol. 17, no 4, p. 331-335Article in journal (Refereed)
    Abstract [en]

    Spectacular color changes of fishes, frogs and other lower vertebrates are due to the motile activities of specialized pigment containing cells. Pigment cells are interesting for biosensing purposes since they provide an easily monitored physiological phenomenon. Melanophores, containing dark brown melanin pigment granules, constitute an important class of chromatophores. Their melanin-filled pigment granules may be stimulated to undergo rapid dispersion throughout the melanophores (cells appear dark), or aggregation to the center of the melanophores (cells appear light). This simple physiological response can easily be measured in a photometer. Selected G protein coupled receptors can be functionally expressed in cultured frog melanophores. Here, we demonstrate the use of recombinant frog melanophores as a biosensor for the detection of opioids. Melanophores were transfected with the human opioid receptor 3 and used for opiate detection. The response to the opioid receptor agonist morphine and a synthetic opioid peptide was analyzed by absorbance readings in an aggregation assay. It was shown that both agonists caused aggregation of pigment granules in the melanophores, and the cells appeared lighter. The pharmacology of the expressed receptors was very similar to its mammalian counterpart, as evidenced by competitive inhibition by increasing concentrations of the opioid receptor inhibitor naloxone. Transfection of melanophores with selected receptors enables the creation of numerous melanophore biosensors, which respond selectively to certain substances. The melanophore biosensor has potential use for measurement of substances in body fluids such as saliva, blood plasma and urine.

  • 336.
    Karlsson, Annika M.
    et al.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Lerner, Michael R.
    Department of Dermatology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
    Unett, David
    Department of Dermatology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Svensson, Samuel P.S.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Melatonin-induced organelle movement in melanophores is coupled to tyrosine phosphorylation of a high molecularweight protein2000In: Cellular signalling, ISSN 0898-6568, Vol. 12, no 7, p. 469-474Article in journal (Refereed)
    Abstract [en]

    Melanophores, brown to black pigment cells from, for example, Xenopus laevis, contain mobile melanin filled organelles, and are well suited for studies on organelle movement. The intracellular regulation of the movement seems to be controlled by serine and threonine phosphorylations and dephosphorylations. Melatonin induces aggregation of the melanosomes to the cell centre through a Gi/o-protein-coupled receptor, Mel1c, which leads to an inhibition of PKA and a stimulation of PP2A. However, this study shows that the melatonin-induced aggregation of melanosomes is also accompanied by tyrosine phosphorylation of a protein with a molecular weight of 280 kDa. Cells pre-incubated with genistein, an inhibitor of tyrosine phosphorylations, showed inhibited melanosome movement after melatonin stimulation, and a lower degree of tyrosine phosphorylation of the 280 kDa protein. The adenylyl cyclase activator forskolin, and the Gi/o protein inhibitor pertussis toxin, also inhibited tyrosine phosphorylation of the 280 kDa protein. The results indicate that melatonin stimulation generates tyrosine phosphorylation of a high molecular weight protein, an event that seems to be essential for melanosome aggregation.

  • 337.
    Karlsson, L M
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tengvall, Pentti
    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.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Adsorption of human serum albumin in porous silicon gradients2003Conference paper (Other academic)
    Abstract [en]

    Backside etching has been utilized to produce gradients of pore size and layer thickness in porous silicon. Human serum albumin (HSA) was adsorbed on such gradients at two different pH values: 4.9, the pI of HSA, and 7.4, the physiological pH. The samples were investigated by scanning electron microscopy, spectroscopic ellipsometry, and autoradiography. The results show that the protein adsorbed displays a gradient along with the pore size and the thickness gradient. The higher than current density used during etching, the more sway-back shaped curves were seen for the protein adsorption pattern, independent of pH. When 50 mA/cm2 current density was used during etching, the quota between the maximal intensity value and the plateau value seen after adsorption of the HSA increased for pH 7.4.

  • 338.
    Karlsson, L M
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tengvall, Pentti
    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.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Back-side etching A tool for making morphology gradients in porous silicon2002In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, no 12Article in journal (Refereed)
    Abstract [en]

    A new method for preparing morphology gradients in electrochemically etched porous silicon layers in presented. The idea is to etch on the back side of the anode and thus utilize and inhomogenous electric field to control the pore size along a surface. The etching procedure resulted in a complex gradient in pore size, porosity, and porous layer thickness, which was studied by spectroscopic ellipsometry and scanning electron microscopy. The gradients are of interest, e.g., for biomaterials research, bio-sensor applications, and for basic studies of adsorption of organic molecules, like proteins. In order to investigate the potential of the gradient surfaces for protein adsorption studies, these were exposed to human serum albumin, and a gradient in the amount of adsorbed protein was observed.

  • 339.
    Karlsson, L M
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tengvall, Pentti
    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.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Penetration and loading of human serum albumin in porous silicon layers with different pore sizes and thicknesses2003In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 266, no 1, p. 40-47Article in journal (Refereed)
    Abstract [en]

    Human serum albumin was adsorbed into porous silicon layers with thickness up to 3 µm and with different mean pore radius in the range 4.5-10 nm. The adsorbed amount of protein was quantified by I125 radioactive labeling techniques and ellipsometry. The results show that albumin penetrated into the pores when the mean pore radius was larger than 5.5 nm, but could not totally occupy the available surface area when the layer thickness was larger than 1 µm. Loading of albumin both into porous layers and onto plane silicon as a function of albumin concentration was also investigated. These measurements show that loading of protein increased with protein concentration at least up to 10 mg/ml for porous silicon and up to 1 mg/ml for plane silicon. The maximum deposition into the type of porous layers used here was 28 µg/cm2, compared to 0.36 µg/cm2 for plane silicon. © 2003 Elsevier Inc. All rights reserved.

  • 340.
    Kerdsongpanya, Sit
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Buchholt, Kristina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Phase-stabilization and substrate effects on nucleation and growth of (Ti,V)(n+1)GeC(n) thin films2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 5, article id 053516Article in journal (Refereed)
    Abstract [en]

    Phase-pure epitaxial thin films of (Ti,V)(2)GeC have been grown onto Al(2)O(3)(0001) substrates via magnetron sputtering. The c lattice parameter is determined to be 12.59 A, corresponding to a 50/50 Ti/V solid solution according to Vegards law, and the overall (Ti,V): Ge: C composition is 2:1:1 as determined by elastic recoil detection analysis. The minimum temperature for the growth of (Ti,V)(2)GeC is 700 degrees C, which is the same as for Ti(2)GeC but higher than that required for V(2)GeC (450 degrees C). Reduced Ge content yields films containing (Ti,V)(3)GeC(2) and (Ti,V)(4)GeC(3). These results show that the previously unknown phases V(3)GeC(2) and V(4)GeC(3) can be stabilized through alloying with Ti. For films grown on 4H-SiC(0001), (Ti,V)(3)GeC(2) was observed as the dominant phase, showing that the nucleation and growth of (Ti,V)(n+1)GeC(n) is affected by the choice of substrate; the proposed underlying physical mechanism is that differences in the local substrate temperature enhance surface diffusion and facilitate the growth of the higher-order phase (Ti,V)(3)GeC(2) compared to (Ti,V)(2)GeC.

  • 341.
    Khranovskyy, Volodymyr
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Eriksson, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Oxygen absorption effect on the sensitivity and material stability of ZnO nanostructured films2008In: Proceedings of IEEE Sensors, IEEE , 2008, p. 874-877Conference paper (Refereed)
    Abstract [en]

    In this work the effect of ambient influence on the electrical conductivity of ZnO films has been studied. Nanostructured ZnO films (undoped and Ga, Co, Mn doped) were exposed to oxygen (1-80 vol.%) at temperature range 300-500degC. A dominant effect of ambient influence via oxygen absorption was observed: the intensity of conductivity decrease was found to be proportional with temperature and tends to saturation with time. After oxygen saturation the reversible effect of oxygen adsorption became dominant and contributed to the films conductivity. Oxygen exposed undoped ZnO films revealed high sensitivity for oxygen content change in the ambience, therefore they have been further processed for gas sensor fabrication.

  • 342.
    Khranovskyy, Volodymyr
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Eriksson, Jens
    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.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Effect of oxygen exposure on the electrical conductivity and gas sensitivity of nanostructured ZnO films2009In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 6, p. 2073-2078Article in journal (Refereed)
    Abstract [en]

    Nanostructured ZnO films (Undoped and Ga, Co, Mn doped) were exposed to oxygen (1-80 vol.%) at temperature range of 300-500 degrees C in order to reveal the ambience-temperature effect oil the electrical conductivity. The dominant effect of ambient influence via oxygen absorption was observed: the intensity of conductivity decrease was found to be proportional with temperature and tends to saturate with time. It is demonstrated that oxygen absorption occurs accordingly to diffusion law and the quantifying of oxygen diffusion was realized for different samples. It is revealed that the type of dopant affects the diffusion in ZnO and the tendency to increase the diffusion intensity with dopant content has been observed. After oxygen saturation the reversible effect of oxygen adsorption became dominant and contributed to the films conductivity. Oxygen exposure undoped ZnO films revealed high sensitivity for oxygen content change in the ambience therefore they have been preceded further for gas sensor design and the detailed investigation of films sensing properties has been carried out.

  • 343.
    Khranovskyy, Volodymyr
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Lashkarev, G
    Lazorenko, V
    Eriksson, Jens
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Investigation of oxygen exposure effect on electrical properties of ZnO based nanostructures films - a premise for sensor design2008In: Sensors electronics and Microsystem Technology Conference,2008, 2008Conference paper (Refereed)
    Abstract [en]

          

  • 344.
    Klenkar, Goran
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Valiokas, Ramunas
    IFM .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Tinazli, A.
    Tampé, R.
    Piehler, J.
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Micro-fabricated array chips based on multivalent chelating thiols: production, characterization and application2006Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Posterbidrag på Biosensors 2006 kongress, Toronto, Kanada, 10-12 maj

  • 345.
    Klenkar, Goran
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Valiokas, Ramunas
    Molecular Compounds Physics Laboratory, Institute of Physics, Vilnius, Lithuania.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Tinazli, Ali
    Institute of Biochemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany.
    Tampé, Robert
    Institute of Biochemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany.
    Piehler, Jacob
    Institute of Biochemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Piezo Dispensed Microarray of Multivalent Chelating Thiols for Dissecting Complex Protein-Protein Interactions2006In: Analytical Chemistry, ISSN 0003-2700, Vol. 78, no 11, p. 3643-3650Article in journal (Refereed)
    Abstract [en]

    The fabrication of a novel biochip, designed for dissection of multiprotein complex formation, is reported. An array of metal chelators has been produced by piezo dispensing of a bis-nitrilotriacetic acid (bis-NTA) thiol on evaporated gold thin films, prestructured with a microcontact printed grid of eicosanethiols. The bis-NTA thiol is mixed in various proportions with an inert, tri(ethylene glycol) hexadecane thiol, and the thickness and morphological homogeneity of the dispensed layers are characterized by imaging ellipsometry before and after back-filling with the same inert thiol and subsequent rinsing. It is found that the dispensed areas display a monotonic increase in thickness with increasing molar fraction of bis-NTA in the dispensing solution, and they are consistently a few Ångströms thicker than those prepared at the same molar fraction by solution self-assembly under equilibrium-like conditions. The bulkiness of the bis-NTA tail group and the short period of time available for chemisorption and in-plane organization of the dispensed thiols are most likely responsible for the observed difference in thickness. Moreover, the functional properties of this biochip are demonstrated by studying multiple protein−protein interactions using imaging surface plasmon resonance. The subunits of the type I interferon receptor are immobilized as a composition array determined by the surface concentration of bis-NTA in the array elements. Ligand dissociation kinetics depends on the receptor surface concentration, which is ascribed to the formation of a ternary complex by simultaneous interaction of the ligand with the two receptor subunits. Thus, multiplexed monitoring of binding phenomena at various compositions (receptor densities) offers a powerful tool to dissect protein−protein interactions.

  • 346.
    Klingvall, Roger
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Eriksson, Mats
    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 .
    SLPT studies of a MISiC device2005In: IEEE Sensors 2005,2005, 2005Conference paper (Refereed)
  • 347.
    Klingvall, Roger
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Eriksson, Mats
    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 .
    UV-SLPT for gas sensor research on MISiC devices2007In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 7, no 03-Apr, p. 592-599Article in journal (Refereed)
    Abstract [en]

    A modified Scanning Light Pulse Technique (SLPT) setup that can be used to evaluate SiC-based gas-sensitive field-effect devices is introduced. This is exemplified with measurements on a Pt-MISiC capacitor that has a metal thickness gradient. The device shows large responses to hydrogen and ammonia in air. The H-2 and NH3 responses show a complementary dependence on the Pt film thickness at 140 degrees C. The temperature dependence differs however for the two gases. The measurement setup uses UV transparent optics together with mechanical chopping of light from a short wavelength light source. The spatial resolution of the system is found to be approximately 50 mu m.

  • 348.
    Klingvall, Roger
    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, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Robust gas detection at sub ppm concentrations2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 160, no 1, p. 571-579Article in journal (Refereed)
    Abstract [en]

    Gas sensors often suffer from signal drift and long response and recovery times, giving rise to problems to evaluate the steady state gas response. It is shown that these problems can be reduced by modulating the test gas concentration and utilizing the change in the slope of the sensor signal as the sensor response feature. The case of low hydrogen concentration detection is studied using a light pulse technique and a PdPt-MIS field-effect device. For the difference in slope method it was possible to reduce the measurement time from hours in the steady state measurements to 1 + 1 min (test gas + reference gas exposure time) and still achieve a detection limit of about 40 ppb for a step change in hydrogen concentration. Such measurements could be made in spite of a drifting baseline caused, e.g. by previous hydrogen exposures. A theoretical model of how a step change in the hydrogen partial pressure affects the difference in slope is given. The model also predicts a non-reactive hydrogen sticking probability (i.e. the probability that an incoming hydrogen molecule from the gas phase will contribute to the response) of about 1 x 10(-8) at 100 ppb H(2), which is about 2 orders of magnitude lower than the reactive sticking coefficient. (C) 2011 Elsevier B.V. All rights reserved.

  • 349.
    Klingvall, Roger
    et al.
    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 .
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Sub ppm detection of hydrogen2008In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 8, no 03-Apr, p. 301-307Article in journal (Refereed)
    Abstract [en]

    A light pulse technique and a field-effect device were used to detect small concentration steps of hydrogen in air. The detection limit was lower than 40 ppb, which is at least one order of magnitude lower than previously reported measurements (with field-effect devices) of hydrogen concentration in air. The device structure was a metal-insulator-semiconductor capacitor with a metal double layer with 17.5 nm Pd (upper layer) and 7.5 nm Pt on a SiO2 insulator and a Si substrate.

  • 350.
    Klingvall, Roger
    et al.
    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 .
    Löfdahl, Mikael
    AppliedSensor AB.
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    A combinatorial approach for field-effect gas sensor research and development2005In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 5, no 5, p. 995-1003Article in journal (Refereed)
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