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  • 1. Abom, A.E.
    et al.
    Comini, E.
    Sberveglieri, G.
    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 .
    Thin oxide films as surface modifiers of MIS field effect gas sensors2002In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 85, no 1-2, p. 109-119Article in journal (Refereed)
    Abstract [en]

    The catalytic activity at the surface of Pt based MIS field effect gas sensors is modified by the deposition of thin films of SnO2, Al2O3 and SiO2, grown by reactive sputtering. It is found that a very thin layer (<10 nm) of SiO2 and SnO2 changes the catalytic activity towards higher NH3 selectivity, but with thicker films the sensor response vanishes. Since the response mechanism for these sensors is dependent on dissociation of molecules, it is likely that at low temperatures (140 °C), neither dissociation on nor transport/diffusion through the thicker films takes place. However, with Pt in conjunction with SiO2 or SnO2, the surface reactions will be altered, with enhanced NH3 selectivity as a result. A thin film of Al2O3, on the other hand, has a much smaller influence on the gas response to the test gases used in this work. Furthermore the sputtering process is found to strongly influence the sensor responses, and specifically reduce the sensitivity of the sensor. A thin intermediate layer of evaporated Pt does not completely protect the underlying structure from sputter induced damage. © 2002 Elsevier Science B.V. All rights reserved.

  • 2. Abom, A.E.
    et al.
    Haasch, R.T.
    Frederick Seitz Mat. Res. Laboratory, University of Illinois, Urbana, IL 61801, United States.
    Hellgren, N.
    Frederick Seitz Mat. Res. Laboratory, University of Illinois, Urbana, IL 61801, United States.
    Finnegan, N.
    Frederick Seitz Mat. Res. Laboratory, University of Illinois, Urbana, IL 61801, United States.
    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 .
    Characterization of the metal-insulator interface of field-effect chemical sensors2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 12, p. 9760-9768Article in journal (Refereed)
    Abstract [en]

    The metal-insulator interface of hydrogen-sensitive metal-insulator-semiconductor capacitors, with SiO2 as the insulator and Pt as the metal contact, was discussed. It was found that the difference in hydrogen response between differently prepared devices was explained by a difference in concentration of available adsorption sites. The analysis showed that the concentration of Pt atoms in contact with the oxide affected both the hydrogen response and the metal-oxide adhesion.

  • 3. Abom, A.E.
    et al.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    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 .
    Influence of gate metal film growth parameters on the properties of gas sensitive field-effect devices2002In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 409, no 2, p. 233-242Article in journal (Refereed)
    Abstract [en]

    Thin films of Pt have been grown as gate metals on the oxide surface of gas sensitive field-effect devices. Both electron beam evaporation and dc magnetron sputtering has been used. The energy of the impinging Pt atoms, the substrate temperature and the thickness of the Pt film were used as parameters in this study. The influence of the growth parameters on the gas response has been investigated and compared with the properties of the films, studied by transmission electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The conditions during growth of the Pt film are found to have a large impact on the properties of the device. As expected, crystallinity, morphology and the metal/substrate interfacial structure are also affected by processing parameters. Three different growth processes stand out as the most promising from gas sensor considerations, namely room temperature evaporation, sputtering at high pressures and sputtering at high temperatures. The correlation between gas responses and properties of the gas sensitive layer is discussed. © 2002 Elsevier Science B.V. All rights reserved.

  • 4.
    Becker, Elin
    et al.
    Competence Centre for Catalysis and the Department Chemical and Biological Engineering, Chalmers, University of Technology, Gothenburg.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Eriksson, Mats
    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.
    Skoglundh, Magnus
    Competence Centre for Catalysis and the Department Chemical and Biological Engineering, Chalmers, University of Technology, Gothenburg.
    Study of the Sensing Mechanism Towards Carbon Monoxide of Platinum-Based Field Effect Sensors2011In: IEEE SENSORS JOURNAL, ISSN 1530-437X, Vol. 11, no 7, p. 1527-1534Article in journal (Refereed)
    Abstract [en]

    We have investigated the temperature dependence and the effect of hydrogen on the CO response of MISiC field effect device sensors. The evolution of adsorbates on a model sensor was studied by in situ DRIFT spectroscopy and correlated to sensor response measurements at similar conditions. A strong correlation between the CO coverage of the sensor surface and the sensor response was found. The temperature dependence and hydrogen sensitivity are partly in agreement with these observations, however at low temperatures it is difficult to explain the observed increase in sensor response with increasing temperature. This may be explained by the reduction of a surface oxide or removal of oxygen from the Pt/SiO2 interface at increasing temperatures. The sensing mechanism of MISiC field effect sensors is likely complex, involving several of the factors discussed in this paper.

  • 5.
    Cavanillas, Santiago
    et al.
    University of Barcelona, Spain.
    Winquist, Fredrik
    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, Chemical and Optical Sensor Systems. Linköping University, The Institute of Technology.
    A self-polishing platinum ring voltammetric sensor and its application to complex media2015In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 859, p. 29-36Article in journal (Refereed)
    Abstract [en]

    A self-polishing voltammetric sensor was recently developed and has been applied to samples of urea, milk and sewage water. The polishing device continuously grinds a platinum ring electrode, offering a reproducible and clean electrode surface. Principal component analysis (PCA) and partial least squares (PLS) techniques were applied to interpret the data and to build prediction models. In an evaluation of samples with different urea concentrations, the grinding step allows for repeatable measurements, similar to those after electrochemical cleaning. Furthermore, for the determination of sewage water concentrations in drinking water and for the evaluation of different fat contents in milk samples, the polishing eliminates sensor drift produced by electrode fouling. The results show that the application of a self-polishing unit offers a promising tool for electrochemical studies of difficult analytes and complex media. (C) 2014 Elsevier B.V. All rights reserved.

  • 6.
    Ekedahl, Lars-Gunnar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Hydrogen sensing mechanisms of metal insulator interfaces1998In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 31, no 5, p. 249-256Article in journal (Refereed)
    Abstract [en]

    The hydrogen sensitivity of palladium-silicon dioxidesilicon (Pd-MOS) structures was demonstrated about 25 years ago. One of the most interesting features of the Pd-MOS device as a hydrogen sensor is its very large dynamic pressure range. Such devices are now used in several practical applications and in commercially available equipment, both as single sensors and in sensor arrays. We recall that the hydrogen sensitivity of the device occurs due to a hydrogen induced polarization at the Pd-SiO2 interface as schematically shown in Figure 1. During the years, several types of devices have been developed, both with insulators other than silicon dioxide and catalytic metals other than palladium. Furthermore, it has been demonstrated that sensors with thin, discontinuous catalytic metals can detect molecules, like ammonia, which are not detected by sensors with thick continuous palladium gates. 1-3 Although several insulators have been used in hydrogen sensitive Pd-insulator-semiconductor

  • 7. 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.

  • 8.
    Eriksson, Mats
    Linköping University, Department of Physics, Measurement Technology, Biology and Chemistry. Linköping University, The Institute of Technology.
    Surface and Interface Phenomena Studied with Pd Metal-Oxide-semiconductor Structures: Adsorption, catalytic reactions, hydrogen sensing and Pd restructuring1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The electronic properties of palladium metal-oxide-semiconductor (Pd-MOS) structures are highly sensitive to hydrogen over a large pressure range. Such devices have been found useful in several applications, e.g. as a chemical sensing element in the so called electronic nose. This thesis takes its starting point in fundamental studies of the physics and chemistry of Pd-MOS structures and presents a model for its hydrogen sensing properties as well as addressing a number of questions of more general nature, relating to heterogeneous catalysis.

    The hydrogen sensitivity rests on the permeability of Pd to hydrogen and consecutive hydrogen adsorption at the Pd-SiO2 interface. Previous studies have shown that the hydrogen response follows a so called Temkin adsorption isotherm, i.e. the response is proportional to the logarithm of the hydrogen pressure. In this work it is shown that an electrostatic model describing the hydrogen adsorbate-adsorbate interaction at the interface, can explain this behavior as well as other, previously obtained, results. In addition to the dominating hydrogen adsorption interface state, a new state has been observed. This state appears to be located at the Pd side of the interface, in contrast to the dominating state which is located at the SiO2 side.

    The hydrogen sensitivity of the device has been utilized, in combination with mass spectrometry, to study hydrogen and CO coadsorption phenomena in ultrahigh vacuum (UHV). It is shown that, although CO by itself does not induce any response of the device, CO may significantly influence the hydrogen response. This is particularly evident in the presence of oxygen. It is shown that CO adsorbed on the Pd surface may act as a valve, hindering both hydrogen adsorption and desorption. Combined, real time, measurements of hydrogen desorption and absorption show that both processes may be induced simultaneously by CO exposure of an hydrogen covered surface. This phenomenon has only been indirectly observed in the past.

    Morphology changes of thin Pd films, evaporated on SiO2 at room temperature, have been followed, both in UHV and at atmospheric pressures. The techniques used include scanning force microscopy, transmission electron microscopy, ultraviolet photoemission spectroscopy, capacitance measurements and mass spectrometry. It has been found that Pd films with a thickness in the range 2-10 nm change their structure dramatically, even at temperatures as low as 473 K, if the surface is properly cleaned: An initially continuous film breaks up and large Pd islands are gradually formed. Carbonaceous species adsorbed on the Pd surface significantly lower the rate of restructuring and, in effect, lock the film in a certain stage of the restructuring process. The carbonaceous adsorbates can be removed by combustion with oxygen whereby the restructuring process restarts.

    Also, the catalytic oxidation of CO and H2 on both continuous and discontinuous Pd films has been studied in UHV. In the case of CO oxidation on a continuous Pd film, a modelling of the surface reaction kinetics was performed and good agreement with experimental results has been achieved. The discontinuous Pd film can be considered as a model catalyst. The interpretation of the experimental results from this study include phenomena occurring on the SiO2 support surface (spillover effects).

    List of papers
    1. A model of the Temkin isotherm behaviour for hydrogen adsorption at Pd-SiO2 interfaces
    Open this publication in new window or tab >>A model of the Temkin isotherm behaviour for hydrogen adsorption at Pd-SiO2 interfaces
    1997 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 82, no 6, p. 3143-3146Article in journal (Refereed) Published
    Abstract [en]

    A simple electrostatic model of the adsorbate–adsorbateinteraction of hydrogen atoms at a Pd–SiO 2 interface is presented. The model predicts a hydrogen adsorption isotherm of the Temkin type. It is found that, in practice, an upper limit for the hydrogen response of a Pd-metal-oxide-semiconductor device exists. The value (in V) is equal to the difference of the initial heats of adsorption (in eV) of the interface and the Pd bulk, respectively. Furthermore, a corresponding maximum hydrogen concentration, at the interface, of 1×10 18  m −2 is predicted. The predictions are in good agreement with previously observed experimental data.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-118342 (URN)10.1063/1.366158 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
    2. Hydrogen adsorption states at the Pd-SiO2 interface and simulation of the response of a Pd metal-oxide-semiconductor hydrogen sensor
    Open this publication in new window or tab >>Hydrogen adsorption states at the Pd-SiO2 interface and simulation of the response of a Pd metal-oxide-semiconductor hydrogen sensor
    1998 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 83, no 8, p. 3947-3951Article in journal (Refereed) Published
    Abstract [en]

    The response of a Pd–SiO 2 –Si hydrogen sensor depends on the reaction kinetics of hydrogen on the Pd surface and on the hydrogen adsorption states at the Pd/SiO 2 interface. In this work we show that besides the dominating hydrogen adsorption state located on the oxide side of the interface, a second state, resulting in opposite hydrogen polarization, exists. This state is possibly a reminiscence of the hydrogen adsorption state on a clean Pd surface. Taking both states into account, a simulation of the hydrogen response over more than ten decades in hydrogen pressures gives good agreement with published data.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-118341 (URN)10.1063/1.367150 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
    3. The influence of CO on the response of hydrogen sensitive Pd-MOS devices
    Open this publication in new window or tab >>The influence of CO on the response of hydrogen sensitive Pd-MOS devices
    1997 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 42, no 3, p. 217-223Article in journal (Refereed) Published
    Abstract [en]

    In order to understand and correctly interpret the response of chemical sensors under measurement conditions, detailed studies of molecule—sensor interactions under well-controlled conditions are needed. In this work, the influence of CO on the response of a hydrogen sensitive Pd—metal-oxide-semiconductor (Pd—MOS) device with a dense Pd film is studied in ultrahigh vacuum (UHV). The results show that although CO by itself does not induce any response of the device, CO may have a significant influence on the hydrogen response, especially so in the presence of oxygen. It is also shown that high CO coverages on the Pd surface increases the time needed to obtain equilibrium between the gas phase hydrogen pressure and the response of the Pd—MOS device. This is due to a CO induced increase of the activation energies of the dissociation and association processes for hydrogen. The effect on the hydrogen response is small for CO coverages below 0.2 monolayers and increases dramatically above this coverage.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-118344 (URN)10.1016/S0925-4005(97)80338-3 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
    4. The catalytic oxidation of CO on polycrystalline Pd: Experiments and kinetic modelling
    Open this publication in new window or tab >>The catalytic oxidation of CO on polycrystalline Pd: Experiments and kinetic modelling
    1998 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 412/413, p. 430-440Article in journal (Refereed) Published
    Abstract [en]

    The catalytic oxidation of CO on a thin, polycrystalline Pd film has been studied. Even though the Pd film is expected to be dominated by (111) facets, some distinct differences compared to single crystalline Pd(111) are observed. A kinetic model for the CO oxidation reaction is presented. It gives good agreement with experiments, both in terms of CO2 reaction probability and CO coverage during reaction conditions. The model assumes a random distribution of the adsorbates, an activation energy for the reaction that decreases with increasing CO coverage, as well as a CO sticking coefficient that in a temperature dependent fashion depends on the oxygen coverage. Single crystal data available from the literature (initial sticking coefficients and heats of adsorption) were mainly used as input parameters. Thus, the model might also be a useful starting point when modeling the catalytic oxidation of CO on single crystal surfaces.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-118337 (URN)10.1016/S0039-6028(98)00462-2 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
    5. Morphology changes of thin Pd films grown on SiO2: influence of adsorbates and temperature
    Open this publication in new window or tab >>Morphology changes of thin Pd films grown on SiO2: influence of adsorbates and temperature
    Show others...
    1999 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 342, no 1-2, p. 297-306Article in journal (Refereed) Published
    Abstract [en]

    Under certain conditions morphology changes occur when thin Pd films, grown on SiO2 at room temperature, are subject to elevated temperatures. First holes in the metal are observed, followed by network formation and finally isolation of metal islands. This process is known as agglomeration. The influence of gas exposures on this restructuring process has been studied by following variations in the capacitance of the structure and by atomic force microscopy, transmission electron microscopy and ultraviolet photoelectron spectroscopy. The capacitance measurements show that carbonaceous species have an impeding influence on the rate of agglomeration and may lock the film structure in a thermodynamic non-equilibrium state. By removing these species with oxygen exposure, i.e. by forming volatile CO and CO2, a clean surface is obtained and the agglomeration process can proceed. High oxygen or hydrogen coverages also lower the rate of restructuring, compared to the case of a clean surface. For the clean Pd surface, an apparent activation energy of 0.64 eV is found for the restructuring process.

    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-118324 (URN)10.1016/S0040-6090(98)01395-9 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
    6. The water-forming reaction on thin, SiO2 supported, palladium films
    Open this publication in new window or tab >>The water-forming reaction on thin, SiO2 supported, palladium films
    1990 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 41, no 1-3, p. 137-138Article in journal (Refereed) Published
    Abstract [en]

    The water-forming reaction has been studied on thin Pd films, evaporated on planar SiO2 substrates. The nominal film thickness varied between 5 and 100 Å. The studies were performed in uhv by means of mass spectrometry, UPS and work function measurements in the temperature range 323–523 K. The film structure was also studied with TEM. The results are compared with previous measurements on 1000 Å, thick, homogeneous Pd films. The structure of the thin Pd films changed dramatically during cyclic H2 and O2 exposures, from that of a continuous film with cracks to that of drop-like metal particles. These structural changes are not observed on the thick (1000 Å) Pd films. Even though there are large structural changes, the water-forming reaction looks qualitatively the same as on a thick Pd film. The total water production however, decreases with decreasing film thickness. We believe that some minor qualitative differences in the water-forming reaction for different nominal Pd film thicknesses, are due to the increasing PdSiO2 boundary as the thickness is reduced.

    National Category
    Condensed Matter Physics
    Identifiers
    urn:nbn:se:liu:diva-118354 (URN)10.1016/S0042-207X(05)80139-3 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
    7. Spillover of hydrogen, oxygen and carbon monoxide in oxidation reactions on SiO2 supported Pd
    Open this publication in new window or tab >>Spillover of hydrogen, oxygen and carbon monoxide in oxidation reactions on SiO2 supported Pd
    1994 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 311, no 1-2, p. 139-152Article in journal (Refereed) Published
    Abstract [en]

    Oxidation of H2 and CO on large, oxygen preexposed Pd islands supported on SiO2, has been investigated in the temperature range 323 ⩽, T ⩽ 523 K. The results have been compared with the corresponding reactions on a polycrystalline Pd film. A maximum reactive sticking coefficient of 0.9 for H2 and an initial sticking coefficient for O2 of 0.8 on both structures is concluded. The maximum reactive sticking coefficient for CO is 0.85 on the film and apparently larger than unity on the island structure. The results obtained from the island structure can be rationalized if O2 and H2 dissociate on the Pd islands and have the possibility to spillover onto the oxide, while CO adsorbs and reacts both on the Pd islands and on the oxide. Spillover of oxygen occurs in a precursor state and is irreversible with an apparent activation energy of 0.1 eV for the forward reaction.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:liu:diva-118345 (URN)10.1016/0039-6028(94)90485-5 (DOI)
    Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2022-01-20
  • 9.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hydrogen adsorption states at the Pd-SiO2 interface and simulation of the response of a Pd metal-oxide-semiconductor hydrogen sensor1998In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 83, no 8, p. 3947-3951Article in journal (Refereed)
    Abstract [en]

    The response of a Pd–SiO 2 –Si hydrogen sensor depends on the reaction kinetics of hydrogen on the Pd surface and on the hydrogen adsorption states at the Pd/SiO 2 interface. In this work we show that besides the dominating hydrogen adsorption state located on the oxide side of the interface, a second state, resulting in opposite hydrogen polarization, exists. This state is possibly a reminiscence of the hydrogen adsorption state on a clean Pd surface. Taking both states into account, a simulation of the hydrogen response over more than ten decades in hydrogen pressures gives good agreement with published data.

  • 10.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Real time measurements of hydrogen desorption and absorption during CO exposures of Pd: Hydrogen sticking and dissolution1998In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 133, no 1-2, p. 89-97Article in journal (Refereed)
    Abstract [en]

    Combined real time measurements of hydrogen desorption and absorption show that both processes may be induced simultaneously by CO adsorption on a hydrogen-covered Pd surface. The induced absorption is found to be a kinetic effect, where the amount absorbed depends on the hydrogen desorption rate and the CO adsorption rate. In addition to simple site blocking, adsorbed CO induces an increase in the hydrogen desorption energy and an activation barrier for hydrogen dissociation. Both increase linearly with CO coverage for θCO>0.18 ML. Below this coverage, the hydrogen dissociation is non-activated.

  • 11.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. Tekniska högskolan.
    The catalytic oxidation of CO on polycrystalline Pd: Experiments and kinetic modelling1998In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 412/413, p. 430-440Article in journal (Refereed)
    Abstract [en]

    The catalytic oxidation of CO on a thin, polycrystalline Pd film has been studied. Even though the Pd film is expected to be dominated by (111) facets, some distinct differences compared to single crystalline Pd(111) are observed. A kinetic model for the CO oxidation reaction is presented. It gives good agreement with experiments, both in terms of CO2 reaction probability and CO coverage during reaction conditions. The model assumes a random distribution of the adsorbates, an activation energy for the reaction that decreases with increasing CO coverage, as well as a CO sticking coefficient that in a temperature dependent fashion depends on the oxygen coverage. Single crystal data available from the literature (initial sticking coefficients and heats of adsorption) were mainly used as input parameters. Thus, the model might also be a useful starting point when modeling the catalytic oxidation of CO on single crystal surfaces.

  • 12.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    The influence of CO on the response of hydrogen sensitive Pd-MOS devices1997In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 42, no 3, p. 217-223Article in journal (Refereed)
    Abstract [en]

    In order to understand and correctly interpret the response of chemical sensors under measurement conditions, detailed studies of molecule—sensor interactions under well-controlled conditions are needed. In this work, the influence of CO on the response of a hydrogen sensitive Pd—metal-oxide-semiconductor (Pd—MOS) device with a dense Pd film is studied in ultrahigh vacuum (UHV). The results show that although CO by itself does not induce any response of the device, CO may have a significant influence on the hydrogen response, especially so in the presence of oxygen. It is also shown that high CO coverages on the Pd surface increases the time needed to obtain equilibrium between the gas phase hydrogen pressure and the response of the Pd—MOS device. This is due to a CO induced increase of the activation energies of the dissociation and association processes for hydrogen. The effect on the hydrogen response is small for CO coverages below 0.2 monolayers and increases dramatically above this coverage.

  • 13.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petersson, Lars-Gunnar
    Tekniska högskolan.
    The water-forming reaction on thin, SiO2 supported, palladium films1990In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 41, no 1-3, p. 137-138Article in journal (Refereed)
    Abstract [en]

    The water-forming reaction has been studied on thin Pd films, evaporated on planar SiO2 substrates. The nominal film thickness varied between 5 and 100 Å. The studies were performed in uhv by means of mass spectrometry, UPS and work function measurements in the temperature range 323–523 K. The film structure was also studied with TEM. The results are compared with previous measurements on 1000 Å, thick, homogeneous Pd films. The structure of the thin Pd films changed dramatically during cyclic H2 and O2 exposures, from that of a continuous film with cracks to that of drop-like metal particles. These structural changes are not observed on the thick (1000 Å) Pd films. Even though there are large structural changes, the water-forming reaction looks qualitatively the same as on a thick Pd film. The total water production however, decreases with decreasing film thickness. We believe that some minor qualitative differences in the water-forming reaction for different nominal Pd film thicknesses, are due to the increasing PdSiO2 boundary as the thickness is reduced.

  • 14.
    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.

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  • 15.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lindgren, David
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering.
    Bjorklund, Robert
    Linköping University, Department of Physics, Chemistry and Biology.
    Winquist, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Sundgren, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Drinking water monitoring with voltammetric sensors2011In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 25, p. 1165-1168Article in journal (Refereed)
    Abstract [en]

    Pulsed voltammetry has been applied to drinking water monitoring. This non-selective technique facilitates detection of several different threats to the drinking water. A multivariate algorithm shows that anomaly detection is possible with a minimum of false alarms. Multivariate analysis can also be used to classify different types of substances added to the drinking water. Low concentrations of sewage water contaminating the drinking water can be detected. A network of such sensors is envisaged to facilitate real-time and on-line monitoring of drinking water distribution networks.

  • 16.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    A model of the Temkin isotherm behaviour for hydrogen adsorption at Pd-SiO2 interfaces1997In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 82, no 6, p. 3143-3146Article in journal (Refereed)
    Abstract [en]

    A simple electrostatic model of the adsorbate–adsorbateinteraction of hydrogen atoms at a Pd–SiO 2 interface is presented. The model predicts a hydrogen adsorption isotherm of the Temkin type. It is found that, in practice, an upper limit for the hydrogen response of a Pd-metal-oxide-semiconductor device exists. The value (in V) is equal to the difference of the initial heats of adsorption (in eV) of the interface and the Pd bulk, respectively. Furthermore, a corresponding maximum hydrogen concentration, at the interface, of 1×10 18  m −2 is predicted. The predictions are in good agreement with previously observed experimental data.

  • 17.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Olsson, Lars
    Linköping University, Department of Medical and Health Sciences.
    Erlandsson, Ragnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology.
    Morphology changes of thin Pd films grown on SiO2: influence of adsorbates and temperature1999In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 342, no 1-2, p. 297-306Article in journal (Refereed)
    Abstract [en]

    Under certain conditions morphology changes occur when thin Pd films, grown on SiO2 at room temperature, are subject to elevated temperatures. First holes in the metal are observed, followed by network formation and finally isolation of metal islands. This process is known as agglomeration. The influence of gas exposures on this restructuring process has been studied by following variations in the capacitance of the structure and by atomic force microscopy, transmission electron microscopy and ultraviolet photoelectron spectroscopy. The capacitance measurements show that carbonaceous species have an impeding influence on the rate of agglomeration and may lock the film structure in a thermodynamic non-equilibrium state. By removing these species with oxygen exposure, i.e. by forming volatile CO and CO2, a clean surface is obtained and the agglomeration process can proceed. High oxygen or hydrogen coverages also lower the rate of restructuring, compared to the case of a clean surface. For the clean Pd surface, an apparent activation energy of 0.64 eV is found for the restructuring process.

  • 18.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Petersson, Lars-Gunnar
    Spillover of hydrogen, oxygen and carbon monoxide in oxidation reactions on SiO2 supported Pd1994In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 311, no 1-2, p. 139-152Article in journal (Refereed)
    Abstract [en]

    Oxidation of H2 and CO on large, oxygen preexposed Pd islands supported on SiO2, has been investigated in the temperature range 323 ⩽, T ⩽ 523 K. The results have been compared with the corresponding reactions on a polycrystalline Pd film. A maximum reactive sticking coefficient of 0.9 for H2 and an initial sticking coefficient for O2 of 0.8 on both structures is concluded. The maximum reactive sticking coefficient for CO is 0.85 on the film and apparently larger than unity on the island structure. The results obtained from the island structure can be rationalized if O2 and H2 dissociate on the Pd islands and have the possibility to spillover onto the oxide, while CO adsorbs and reacts both on the Pd islands and on the oxide. Spillover of oxygen occurs in a precursor state and is irreversible with an apparent activation energy of 0.1 eV for the forward reaction.

  • 19.
    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, E-ISSN 1089-7550, 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.

  • 20.
    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)
  • 21.
    Eriksson, Mats
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Winquist, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Diesel detection in surface water in the low ppb range2016In: PROCEEDINGS OF THE 30TH ANNIVERSARY EUROSENSORS CONFERENCE - EUROSENSORS 2016, ELSEVIER SCIENCE BV , 2016, Vol. 168, p. 384-387Conference paper (Refereed)
    Abstract [en]

    A method for diesel detection in surface water in the low ppb range is presented. Even though standard commercial metal oxide gas sensors with detection limits in the ppm range are used, extraction of volatile compounds from the water enables a detection limit of about 2 ppb diesel in the water. The technique can be used for surface water monitoring. The standard technique of ultraviolet fluorescence detection has an interference problem with humic substances. This is not a problem with the suggested technique. Results from lab measurements as well as field tests at a water utility in the Stockholm region in Sweden are presented. (C) 2016 Published by Elsevier Ltd.

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  • 22.
    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.

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  • 23.
    Erlandsson, Ragnar
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Elwing, Hans
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Olsson, Lars
    Linköping University, Department of Medical and Health Sciences. Tekniska högskolan.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wigren, Roger
    Welin Klintström, Stefan
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Scanning force microscopy - examples of applications to surface chemistry1992In: Progress in Colloid and Polymer Science, ISSN 0340-255X, E-ISSN 1437-8027, Vol. 88, p. 154-161Article in journal (Refereed)
    Abstract [en]

    Some recent results from the scanning force microscopy activity at our laboratory are presented. A brief description of attractive mode force microscopy is followed by a discussion of the following examples: O2/H2-induced morphology changes in thin palladium films, structure of spin cast polysulfone films, fibrinogen adsorption on hydrophobic SiO2, and force measurements on hydrophobic/hydrophilic substrates.

  • 24.
    Erlandsson, Ragnar
    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, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Olsson, Lars
    Linköping University, Department of Medical and Health Sciences.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Petersson, Lars-Gunnar
    Gas-induced restructuring of palladium model catalysts studied with atomic force microscopy1991In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 9, no 2, p. 825-828Article in journal (Refereed)
    Abstract [en]

    The structure of thin Pd films evaporated onto planar SiO2 substrates changes dramatically during oxygen/hydrogen exposures in ultrahigh vacuum. In this work we have used an atomic force microscope(AFM), operated in the attractive mode, to obtain the three‐dimensional morphology of the Pd surface for different film thicknesses and treatments, and compared the data with transmission electron microscopy(TEM) micrographs. During restructuring, a 100‐Å film changes from being a smooth continuous film with cracks into metal clusters dispersed on the SiO2 support. In the 5‐Å case the metal films are already well dispersed as fabricated. Here the gas exposure instead results in a clustering effect resulting in larger particles. The AFM gives results which are consistent with TEM micrographs but also gives additional information on metal particle shape which can lead to a further understanding of the restructuring process.

  • 25.
    Fogelberg, J.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Dannetun, Helen
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Petersson, L.-G.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    H2-D2 exchange on an oxygen covered Pd-film: A study of the backreaction on a hydrogen sensitive MOS device1992Conference paper (Refereed)
  • 26. Fogelberg, J.
    et al.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Dannetun, Helen
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Petersson, L.-G.
    Kinetic modelling of hydrogen ad/absorption in thin films of hydrogen sensitive field effect devices: Observation of large hydrogen induced dipoles at the Pd/SiO2 interface1995In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, ISSN 0021-8979, Vol. 78, p. 988-Article in journal (Refereed)
    Abstract [en]

    A kinetic modeling of the hydrogen interaction with a Pd‐SiO2‐Si (Pd‐MOS) device is reported. The model is fitted to a number of experimental results, mainly from mass spectrometric desorption measurements. The new results verify an older description of the energetics of hydrogen adsorption states at the Pd/SiO2 interface in the sense that the adsorption may be described by a so‐called Temkin isotherm; however, several new findings have to be incorporated into the model in order to obtain a consistent picture. The initial heat of adsorption at the interface is around 0.8 eV/hydrogen atom. The number of adsorption sites at the interface is considerably smaller than at the surface, 6×1017 m−2 versus 1.5×1019 m−2. Furthermore, the interface hydrogen atoms are strongly polarized. An average value of 2 Debye is obtained. It is the large hydrogen polarization at the Pd/SiO2 interface and not a large concentration of adsorbed hydrogen atoms per se which accounts for the very high sensitivity of a Pd‐MOS device as hydrogen sensor

  • 27.
    Holmin, Susanne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Krantz-Rulcker, Christina
    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.
    Investigation of Electrode Materials as Sensors in a Voltammetric Electronic Tongue2002In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 14, no 12, p. 839-847Article in journal (Refereed)
    Abstract [en]

    In this work different electrode materials were investigated as sensors in a voltammetric electronic tongue. Basically, the electronic tongue is based on the combination of nonspecific sensors (electrodes) and pattern recognition tools, for example principal component analysis (PCA). Copper. glassy carbon, nickel, palladium, silver, tin, titanium and zirconium together with more traditional electrode materials such as gold, iridium, and platinum were studied. Cyclic voitammetry was applied to study typical model reactions in solutions containing different electroactive compounds, like ascorbic acid, glucose, histidine and potassium hexacyanoferrate(II). Different sensitivity and selectivity were obtained with the electrodes. Large responses were for example found for the amino acid and the carbohydrate using the copper, nickel and silver electrode. Some of the electrodes were employed in multicomponent solutions, i.e., liquid washing detergents from different suppliers together with differential pulse voltammetry. Responses from the electrodes in combination with PCA showed that they separated the detergents to different extents. This was further used when information from the sensors was merged together for successful discrimination of the detergents. It was found that two detergents close to each other in the score plot were from the same supplier. Furthermore. scanning electron microscopy (SEM) was used to monitor surface changes at the nonnoble electrodes (copper, nickel, and silver).

  • 28.
    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.

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  • 29.
    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.

  • 30.
    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)
  • 31.
    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.

  • 32.
    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.

  • 33.
    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.

  • 34.
    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)
  • 35.
    Leffler, T.
    et al.
    Chalmers Univ Technol, Sweden.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Leckner, B.
    Chalmers Univ Technol, Sweden.
    Lind, F.
    Chalmers Univ Technol, Sweden.
    Winquist, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Knutsson, P.
    Chalmers Univ Technol, Sweden.
    Monitoring of bed material in a biomass fluidized bed boiler using an electronic tongue2023In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 340, article id 127598Article in journal (Refereed)
    Abstract [en]

    The thermal conversion of biomass fuel mixes in fluidized beds can cause agglomeration. To counteract agglomeration, bed material is gradually exchanged with virgin bed material, and this results in increased disposal of used bed material. Furthermore, the bed material exchange represents a costly option, as it involves a cost for virgin bed material, for landfill, and for unplanned downtime of the plant. This paper presents a novel method for the evaluation of bed material quality: the electronic tongue (ET). Evaluation of bed material quality can contribute toward decreasing the cost of unnecessary exchanges of bed material. The proposed method was tested on bed material sampled on an almost daily basis from a commercial fluidized bed boiler during several months of operation. A two-electrode ET was used for the evaluation of the bed material quality. The analysis relied on pulsed voltammetry measurements and multivariate data analysis with Principal Component Analysis (PCA). The results suggest that it is possible to follow bed material changes and that the ET, after further development, may be used to optimize the material flows connected to the bed material. Further research is being conducted to optimize the ETs performance and its application in monitoring bed material.

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  • 36.
    Lundström, Ingemar
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Sundgren, Hans
    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 .
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Krantz-Rülcker, Tina
    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 .
    Twenty-five years of field effect gas sensor research in Linköping2007In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 121, no 1, p. 247-262Article in journal (Refereed)
    Abstract [en]

    The present contribution contains an overview of the development of gas sensitive field-effect devices in Linköping during the last 25 years. It is completely centred to the work at the Laboratory of Applied Physics at Linköping University, and is therefore not a proper review of a research field where many important contributions have been made by several other research groups. © 2006 Elsevier B.V. All rights reserved.

  • 37.
    Löfdahl, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Johansson, Martin
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Difference in hydrogen sensitivity between Pt and Pd field-effect devices2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 7, p. 4275-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 38.
    Löfdahl, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    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 .
    Chemical images2000In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 70, no 1-3, p. 77-82Article in journal (Refereed)
    Abstract [en]

    Chemical sensors can be used to generate a vast amount of information about the emissions from bio- and chemical processes, from food and bacteria and from a number of products. These emissions are either wanted or should be avoided. Wolfgang Gopel was one of those who recognized early the large potential of chemical sensor arrays and different modes of operation of a given sensor. We describe how large area field effect devices, with catalytic metal gates, can be used for the construction of a response image of a gaseous emission. More specifically, we discuss the new possibilities obtained through the use of catalytic metals with a gradient in thickness. Some basic features of such sensing surfaces are demonstrated and, finally, time-dependent response images from aging meat are used to demonstrate the potential of the method used. It is based on a scanning light pulse technique (SLPT) which measures local polarization or work function changes in two dimensions and, e.g. a sensing surface consisting of bands of different catalytic metals with a gradient in thickness.

  • 39.
    Löfdahl, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Utaiwasin, C.
    Carlsson, Andreas
    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 .
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Gas response dependence on gate metal morphology of field-effect devices2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 80, no 3, p. 183-192Article in journal (Refereed)
    Abstract [en]

    The dependence of the gas response on the gate metal morphology of field-effect gas sensors has been investigated in a new systematic way by using a scanning light pulse technique (SLPT) together with fabrication of metal gates where the metal morphology is continuously varied over the gate area. With the SLPT the local gas response at different points of the gate area can be measured. Furthermore, a mass spectrometric local gas sampling technique has been applied in combination with the local gas response measurements, which gives complementary information about the surface chemistry and how it changes with the morphology of the metal gate. Three different gate metals, Pd, Pt and Ir, have been studied by analysing the morphology and the gas response to five different gases, H2, NH3, C2H5OH, C2H4 and CH3CHO. Morphological aspects such as crack coverage, concentration of cracks and the length of the crack boundary, have been calculated from acquired scanning electron microscopy (SEM) images. Different possible response mechanisms are discussed in order to explain the observed responses and to understand the role of the morphology and the choice of the catalytic metal. Only in the case of ammonia a direct correlation between the morphological aspects, e.g. crack coverage, and the response was found. For Pd large changes in the local water pressure close to the metal gate surface have been measured at different parts of the metal gate by using the local gas sampling technique and a correlation is observed with the simultaneously measured gas response. Of the response mechanisms discussed in this contribution only a dissociative mechanism, where hydrogen atoms trapped at the interface between the metal gate and the insulator gives the response of the device, is consistent with all obtained results. © 2001 Elsevier Science B.V. All rights reserved.

  • 40.
    Meng, Lingyin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Chirtes, Sorana
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Chinese Univ Hong Kong, Peoples R China.
    A green route for lignin-derived graphene electrodes: A disposable platform for electrochemical biosensors2022In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 218, article id 114742Article in journal (Refereed)
    Abstract [en]

    The tremendous growth of disposable electrode-based portable devices for point-of-care testing requires mass production of disposable electrodes in a low-cost and sustainable manner. Here, we demonstrate a green route for the conversion of biomass lignin, patterning, and reduction of the lignin-derived graphene electrodes by sequential laser lithography, water lift-off and sodium borohydride (NaBH4) treatment, and their use for electrochemical lactate biosensors. Energy-saving and localized laser lithography converted the aromatic ring-rich lignin into porous laser-induced graphene (LIG). The conductivity and attachment of the LIG to the substrate were optimized in a factorial experiment with laser power and scan speed as variables. Characterization results revealed the conversion of partial heteroatoms (e.g., Na, S, O) into granular inorganic compounds on the LIG surface under laser treatment. Water was used as an eco-friendly solvent for the patterning of the LIG (P-LIG) by a lift-off process, where the inorganic residues and un-reacted lignin were dissolved, exposing the macro-/micropores in the P-LIG. NaBH4 induced a reduction of the P-LIG (P-rLIG) resulting in improved electrochemical kinetics with lower charge transfer resistance (27.3 omega) compared to the LIG (248.1 omega) and the P-LIG (61.4 omega). The porous P-rLIG served as a 3D electrode for the deposition of Prussian blue and lactate oxidase for disposable electrochemical lactate biosensors, delivering a good analytical performance towards lactate detection with a linear range up to 16 mM and a high sensitivity (1.21 mu A mM-1). These lignin-derived disposable electrodes, utilizing renewable resources together with low-energy consumption fabrication and patterning, may contribute to the sustainable manufacturing of biosensors for point-of-care and point-of-use applications.

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  • 41.
    Persson, Bertil R.
    et al.
    Lund Univ, Sweden.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Garcia-Tenorio, Rafael
    Univ Seville, Spain.
    Elis Holm, In Memoriam2020Other (Other academic)
    Abstract [en]

    n/a

  • 42.
    Salomonsson, Anette
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Dannetun, Helen
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    HDO formation studied on Pd- and Pt-MIS devices2003Conference paper (Refereed)
  • 43.
    Salomonsson, Anette
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Dannetun, Helen
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hydrogen Interaction with Platinum and Palladium Metal Insulator Semiconductor devices2005In: Journal of Applied Physics, ISSN 0021-8979, Vol. 98, no 1, p. 14505-14514Article in journal (Refereed)
    Abstract [en]

    Hydrogen-sensitivePd–SiO2–Si and Pt–SiO2–Si metal–insulator–semiconductor (MIS) devices have been studied inultrahigh vacuum in the temperature range of 223–523  K. Adsorption/absorption ofhydrogen occurs at the metal surface, in the metal bulk,and at the metal–insulator interface. The sensor signal, caused byhydrogen adsorption at the interface, shows a logarithmic dependence onthe applied hydrogen pressure. The Pt-MIS device, which is fullyfunctional at atmospheric pressures, is sensitive to changes in hydrogenpressure down to the 10–12-Torr scale. We propose that theinterface adsorption follows a so-called Temkin isotherm with an interfaceheat of adsorption that varies with hydrogen coverage as Hi0(1–a).The initial heat of adsorption Hi0 is determined to 0.78  eV/hydrogenatom. The adsorption potential at the external Pt surface isfound to be 0.45  eV/hydrogen atom. These values were obtained bymodeling the hydrogen interaction with the MIS devices and fittingthe model to a number of experimental results. Also studiesof Pd-based devices were performed and compared with Pt. Thehydrogen adsorption on the metal surface, previously treated as afirst-order process on Pd, is shown to follow a second-orderprocess. Qualitatively the results from the Pd- and Pt-MIS devicesagree. Quantitatively there are differences. The hydrogen sensitivity of thePt-MIS device is only approximately one-third compared to that ofthe Pd-MIS structure. This agrees with the result that theconcentration of available hydrogen adsorption sites at the Pt–SiO2 interfaceis approximately 7×1017 m–2 whereas the concentrations of sites at thePd–SiO2 interface is roughly three times larger (2×1018 m–2). An estimateof the size of the dipole moments (0.6–0.7  D) implies thatthe interface hydrogen atoms are strongly polarized. Differences are alsoobserved in the microstructure of the metal films. Atomic forcemicroscopy results show that the Pd surface reconstructs during H2–O2exposures, while the Pt surface shows no such change atthese temperatures.

  • 44.
    Salomonsson, Anette
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Dannetun, Helen
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Hydrogen interaction with Pt- and PdMIS devices2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 98, no 1Article in journal (Refereed)
    Abstract [en]

    Hydrogen-sensitive Pd–SiO2–Si and Pt–SiO2–Si metal–insulator–semiconductor (MIS) devices have been studied in ultrahigh vacuum in the temperature range of 223–523 K. Adsorption/absorption of hydrogen occurs at the metal surface, in the metal bulk, and at the metal–insulator interface. The sensor signal, caused by hydrogen adsorption at the interface, shows a logarithmic dependence on the applied hydrogen pressure. The Pt-MIS device, which is fully functional at atmospheric pressures, is sensitive to changes in hydrogen pressure down to the 10−12-Torr scale. We propose that the interface adsorption follows a so-called Temkin isotherm with an interface heat of adsorption that varies with hydrogen coverage as ΔHi0(1−aθ). The initial heat of adsorption ΔHi0 is determined to 0.78 eV/hydrogen atom. The adsorption potential at the external Pt surface is found to be 0.45 eV/hydrogen atom. These values were obtained by modeling the hydrogen interaction with the MIS devices and fitting the model to a number of experimental results. Also studies of Pd-based devices were performed and compared with Pt. The hydrogen adsorption on the metal surface, previously treated as a first-order process on Pd, is shown to follow a second-order process. Qualitatively the results from the Pd- and Pt-MIS devices agree. Quantitatively there are differences. The hydrogen sensitivity of the Pt-MIS device is only approximately one-third compared to that of the Pd-MIS structure. This agrees with the result that the concentration of available hydrogen adsorption sites at the Pt–SiO2 interface is approximately 7×1017 m−2 whereas the concentrations of sites at the Pd–SiO2 interface is roughly three times larger (2×1018 m−2). An estimate of the size of the dipole moments (0.6–0.7 D) implies that the interface hydrogen atoms are strongly polarized. Differences are also observed in the microstructure of the metal films. Atomic force microscopy results show that the Pd surface reconstructs during H2–O2 exposures, while the Pt surface shows no such change at these temperatures.

  • 45.
    Salomonsson, Anette
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Dannetun, Helen
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hydrogen ad- and absorption on Pt-SiO2-Si structures2001Conference paper (Refereed)
  • 46.
    Scharnagl, K.
    et al.
    Faculty of Electrical Engineering, Institute of Physics, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany.
    Eriksson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Karthigeyan, A.
    DAAD Fellow, Central Electronics Engineering Research Institute, Pilani 333031, India.
    Burgmair, M.
    Faculty of Electrical Engineering, Institute of Physics, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany.
    Zimmer, M.
    Faculty of Electrical Engineering, Institute of Physics, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany.
    Eisele, I.
    Faculty of Electrical Engineering, Institute of Physics, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany.
    Hydrogen detection at high concentrations with stabilised palladium2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 78, no 1-3, p. 138-143Article in journal (Refereed)
    Abstract [en]

    In order to improve the stability to high hydrogen concentrations, of hybrid suspended gate field effect transistors (HSGFETs) with thin palladium films as sensitive layer, Pd-Ni and Pd-Ag alloys have been produced by co-evaporation techniques in UHV. In this paper, the preparation methods as well as hydrogen response measurements are presented. The observed results show that the Pd-Ni alloy is an appropriate material for hydrogen sensing at concentrations up to 2% H2, even at room temperature. The response to 2% H2 is around 500 mV at dry conditions. It is reduced to less than half of this value with moistened carrier gas, but at the same time, the desorption time is lowered. In contrast, the Pd-Ag alloy was not stable. A large drift of the sensor signal was observed and the morphology as well as the composition had changed after the test gas exposures. © 2001 Published by Elsevier Science B.V.

  • 47.
    Sekretareva, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Stanford University, CA 94305 USA.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Correspondence on "Can Nanoimpacts Detect Single-Enzyme Activity? Theoretical Considerations and an Experimental Study of Catalase Impacts"2017In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 5, p. 3591-3593Article in journal (Other academic)
    Abstract [en]

    n/a

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  • 48.
    Sekretareva, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Volkov, Anton V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Screen printed microband array based biosensor for water monitoring2015In: The Frumkin Symposium, 2015Conference paper (Refereed)
  • 49.
    Sekretareva, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Uppsala Univ, Sweden.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Volkov, Anton
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Evaluation of the Electrochemically Active Surface Area of Microelectrodes by Capacitive and Faradaic Currents2019In: ChemElectroChem, E-ISSN 2196-0216, Vol. 6, no 17, p. 4411-4417Article in journal (Refereed)
    Abstract [en]

    Two experimental methods to estimate the electrochemically active surface area (EASA) of microelectrodes are investigated. One method is based on electrocapacitive measurements and depends significantly on the surface roughness as well as on other parameters. The other method is based on faradaic current measurements and depends on the geometric surface area. The experimental results are supplemented with numerical modeling of electrodes with different surface roughness. A systematic study reveals a strong influence of the scale and arrangement of the surface roughness, the measurement potential and the electrolyte concentration on the EASA of microelectrodes estimated from the electrocapacitive measurements. The results show that electrocapacitive measurements should not be used to estimate the faradaic EASA of microelectrodes with a non-negligible surface roughness.

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  • 50.
    Sekretareva, Alina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Volkov, Anton V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor V.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Total phenol analysis of water using a laccase-based microsensor array2015In: Program of the XXIII International Symposium on Bioelectrochemistry and Bioenergetics of the Bioelectrochemical Society. 14-18 June, 2015. Malmö, Sweden, Lausanne: Bioelectrochemical Society , 2015, p. 155-155Conference paper (Other academic)
    Abstract [en]

    The monitoring of phenolic compounds in raw waters and wastewaters is of great importance for environmental control. Use of biosensors for rapid, specific and simple detection of phenolic compounds is a promising approach. A number of biosensors have been developed for phenol detection. A general drawback of previously reported biosensors is their insufficient detection limits for phenols in water samples. One way to improve the detection limit is by the use of microelectrodes.

    Microband design of the microelectrodes combines convergent mass transport due to the microscale width and high output currents due to the macroscopic length. Among the various techniques available for microband electrode fabrication, we have chosen screen-printing which is a cost-effective production method.

    In this study, we report on the development of a laccase-based microscale biosensor operating under a convergent diffusion regime. Screen-printing followed by simple cutting was utilized for the fabrication of graphite microbands as a platform for further covalent immobilization of laccase. Numerical simulations, utilizing the finite element method with periodic boundary conditions, were used for modeling the voltammetric response of the developed microband electrodes. Anodization followed by covalent immobilization was used for the electrode modification with laccase. Direct and mediated laccase bioelectrocatalytic oxidation of phenols was studied on macro- and microscale graphite electrodes. Significant enhancement of the analytical performance was achieved by the establishment of convergent diffusion in the microscale sensor. Finally, the developed microsensor was utilized to monitor phenolic compounds in real waste water.

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