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Special Issue "State-of-the-Art Sensors Technology in Germany"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "State-of-the-Art Sensors Technologies".

Deadline for manuscript submissions: closed (31 March 2009)

Special Issue Editor

Editorial Advisor
Prof. Dr. Ralf Moos

Department of Functional Materials, Faculty of Engineering Science, University of Bayreuth, 95440 Bayreuth, Germany
Website | E-Mail
Fax: +49 (0) 921-55-7405
Interests: gas sensors; automotive sensors; sensor technology

Special Issue Information

Summary

The aim of this special issue is to provide a comprehensive view on the state-of-the-art sensors technology in Germany. Research articles are solicited which will provide a consolidated state-of-the-art in this area. The Special Issue will publish those full research, review and high rated manuscripts addressing the above topic.

Related papers published in 2007 and 2008

Monika Turek1, Lothar Ketterer3, Melanie Claßen4, Heinz K. Berndt4, Gereon Elbers4, Peter Krüger5, Michael Keusgen3 and Michael J. Schöning1,*
Article: Development and Electrochemical Investigations of an EIS- (Electrolyte-Insulator-Semiconductor) based Biosensor for Cyanide Detection
Sensors 2007, 7, 1415-1426 (PDF Format, 893K)

Benjamin Barlen1, Saikat D. Mazumdar1, Olga Lezrich1, Peter Kämpfer2 and Michael Keusgen1,*
Article: Detection of Salmonella by Surface Plasmon Resonance
Sensors 2007, 7, 1427-1446 (PDF Format, 1854)

Hans-Jörg Schneider1,*, Kazuaki Kato1 and Robert M. Strongin2,*
Article: Chemomechanical Polymers as Sensors and Actuators for Biological and Medicinal Applications
Sensors 2007, 7, 1578-1611 (PDF Format, 987K)

Kathy Sahner1,*, Perena Gouma2 and Ralf Moos1
Article: Electrodeposited and Sol-gel Precipitated p-type SrTi1-xFexO3-δ Semiconductors for Gas Sensing
Sensors 2007, 7, 1871-1886 (PDF Format, 445K)

Natascha Oppelt* and Wolfram Mauser
Article: The Airborne Visible / Infrared Imaging Spectrometer AVIS: Design, Characterization and Calibration
Sensors 2007, 7, 1934-1953 (PDF Format, 5925K)

Kai Marxen1,*, Klaus H. Vanselow1, Sebastian Lippemeier2, Ralf Hintze2, Andreas Ruser1 and Ulf-Peter Hansen3
Article: Determination of DPPH Radical Oxidation Caused by Methanolic Extracts of Some Microalgal Species by Linear Regression Analysis of Spectrophotometric Measurements
Sensors 2007, 7, 2080-2095 (PDF Format, 237K)

Michael Schuch, G. A. Groß and J. M. Köhler*
Article: Formation and Fluorimetric Characterization of Micelles in a Micro-flow Through System with Static Micro Mixer
Sensors 2007, 7, 2499-2509 (PDF Format, 232K)

Gunter Hagen*, Anne Schulz, Matthias Knörr and Ralf Moos
Article: Four-Wire Impedance Spectroscopy on Planar Zeolite/Chromium Oxide Based Hydrocarbon Gas Sensors
Sensors 2007, 7, 2681-2692 (PDF Format, 653K)

Tymon Zielinski1,* and Bringfried Pflug2
Article: Lidar-based Studies of Aerosol Optical Properties Over Coastal Areas
Sensors 2007, 7, 3347-3365 (PDF Format, 239K)

Marco Scheidle, Johannes Klinger and Jochen Büchs*
Article: Combination of On-line pH and Oxygen Transfer Rate Measurement in Shake Flasks by Fiber Optical Technique and Respiration Activity MOnitoring System (RAMOS)
Sensors 2007, 7, 3472-3480 (PDF Format, 312K)

Marc Hennemeyer, Stefan Burghardt and Robert W. Stark*
Article: Cantilever Micro-rheometer for the Characterization of Sugar Solutions
Sensors 2008, 8, 10-22 (PDF Format, 3557K)

Lorenz J. Steinbock and Mark Helm*
Article: Wavelength Dependence of Photoinduced Microcantilever Bending in the UV-VIS Range
Sensors 2008, 8, 23-34 (PDF Format, 239K)

Andreas Richter1,*, Georgi Paschew1, Stephan Klatt1, Jens Lienig1, Karl-Friedrich Arndt2 and Hans-Jürgen P. Adler3
Review: Review on Hydrogel-based pH Sensors and Microsensors
Sensors 2008, 8, 561-581 (PDF Format, 776K)

Katrin Schmitt1, Kerstin Oehse2, Gerd Sulz1 and Christian Hoffmann2,*
Review: Evanescent field Sensors Based on Tantalum Pentoxide Waveguides – A Review
Sensors 2008, 8, 711-738 (PDF Format, 1124K)

Sabine Achmann*, Martin Hämmerle and Ralf Moos
Article: Amperometric Enzyme-based Gas Sensor for Formaldehyde: Impact of Possible Interferences
Sensors 2008, 8, 1351-1365 (PDF Format, 491K)

Yunsheng Wang*, Holger Weinacker and Barbara Koch
Article: A Lidar Point Cloud Based Procedure for Vertical Canopy Structure Analysis And 3D Single Tree Modelling in Forest
Sensors 2008, 8, 3938-3951 (PDF Format, 577K)

Beate Strehlitz*, Nadia Nikolaus and Regina Stoltenburg
Article: Protein Detection with Aptamer Biosensorsv
Sensors 2008, 8, 4296-4307 (PDF Format, 87K)

Dirk Sander*, Zhen Tian and Jürgen Kirschner
Article: Cantilever measurements of surface stress, surface reconstruction, film stress and magnetoelastic stress of monolayers
Sensors 2008, 8, 4466-4486 (PDF Format, 879K)

Daniel Odermatt1,*, Thomas Heege2, Jens Nieke1,3, Mathias Kneubühler1 and Klaus Itten1
Article: Water Quality Monitoring for Lake Constance with a Physically Based Algorithm for MERIS Data
Sensors 2008. 8, 4582-4599 (PDF Format, 413K)

Kathy Sahner1,*, Anne Schulz1, Jaroslaw Kita1, Rotraut Merkle2, Joachim Maier2 and Ralf Moos1
Article: CO2 Selective Potentiometric Sensor in Thick-film Technology
Sensors 2008, 8, 4774-4785 (PDF Format, 288K)

Kai Schorstein, Alexandru Popescu, Marco Göbel and Thomas Walther*
Article: Remote Water Temperature Measurements Based on Brillouin Scattering with a Frequency Doubled Pulsed Yb:doped Fiber Amplifier
Sensors 2008, 8, 5820-5831 (PDF Format, 1222)

Jan Dirk Schulze Spuentrup1,*, Joachim N. Burghartz1, Heinz-Gerd Graf1, Christine Harendt1, Franz Hutter1, Markus Nicke2, Uwe Schmidt2, Markus Schubert3 and Juergen Sterzel2
Article: Thin Film on CMOS Active Pixel Sensor for Space Applications
Sensors 2008, 8, 6340-6354 (PDF Format, 367K)

Rudolf Richter
Article: Classification Metrics for Improved Atmospheric Correction of Multispectral VNIR Imagery
Sensors 2008, 8, 6999-7011 (PDF Format, 771K)

Keywords

  • biosensors
  • chemical sensors
  • physical sensors
  • remote sensing sensors

Published Papers (13 papers)

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Research

Jump to: Review

Open AccessArticle Translocation Biosensors – Cellular System Integrators to Dissect CRM1-Dependent Nuclear Export by Chemicogenomics
Sensors 2009, 9(7), 5423-5445; doi:10.3390/s90705423
Received: 15 June 2009 / Revised: 3 July 2009 / Accepted: 3 July 2009 / Published: 9 July 2009
Cited by 12 | PDF Full-text (1634 KB) | HTML Full-text | XML Full-text
Abstract
Fluorescent protein biosensors are powerful cellular systems biology tools for dissecting the complexity of cellular processes with high spatial and temporal resolution. As regulated nucleo-cytoplasmic transport is crucial for the modulation of numerous (patho)physiological cellular responses, a detailed understanding of its molecular mechanism
[...] Read more.
Fluorescent protein biosensors are powerful cellular systems biology tools for dissecting the complexity of cellular processes with high spatial and temporal resolution. As regulated nucleo-cytoplasmic transport is crucial for the modulation of numerous (patho)physiological cellular responses, a detailed understanding of its molecular mechanism would open up novel options for a rational manipulation of the cell. In contrast to genetic approaches, we here established and employed high-content cellular translocation biosensors applicable for dissecting nuclear export by chemicogenomics. A431 cell lines, stably expressing a translocation biosensor composed of glutathione S-transferase, GFP and a rational combination of nuclear import and export signals, were engineered by antibiotic selection and flow cytometry sorting. Using an optimized nuclear translocation algorithm, the translocation response could be robustly quantified on the Cellomics Arrayscan® VTI platform. Subsequent to assay optimization, the assay was developed into a higher density 384-well format high-content assay and employed for the screening of the 17K ChemBioNet compound collection. This library was selected on the basis of a genetic algorithm used to identify maximum common chemical substructures in a database of annotated bioactive molecules and hence, is well-placed in the chemical space covered by bioactive compounds. Automated multiparameter data analysis combined with visual inspection allowed us to identify and to rationally discriminate true export inhibitors from false positives, which included fluorescent compounds or cytotoxic substances that dramatically affected the cellular morphology. A total of 120 potential hit compounds were selected for Cellomics Arrayscan® VTI based rescreening. The export inhibitory activity of 20 compounds effective at concentrations < 25 μM were confirmed by fluorescence microscopy in several cell lines. Interestingly, kinetic analysis allowed the identification of inhibitors capable to interfere with the export receptor CRM1-mediated nuclear export not only in an irreversible, but also in a reversible fashion. In sum, exploitation of biosensor based screening allows the identification of chemicogenomic tools applicable for dissecting nucleo-cytoplasmic transport in living cells. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
Open AccessArticle Magneto-Optical Relaxation Measurements of Functionalized Nanoparticles as a Novel Biosensor
Sensors 2009, 9(6), 4022-4033; doi:10.3390/s90604022
Received: 27 March 2009 / Revised: 21 May 2009 / Accepted: 25 May 2009 / Published: 26 May 2009
Cited by 4 | PDF Full-text (135 KB) | HTML Full-text | XML Full-text
Abstract
Measurements of magneto-optical relaxation signals of magnetic nanoparticles functionalized with biomolecules are a novel biosensing tool. Upon transmission of a laser beam through a nanoparticle suspension in a pulsed magnetic field, the properties of the laser beam change. This can be detected by
[...] Read more.
Measurements of magneto-optical relaxation signals of magnetic nanoparticles functionalized with biomolecules are a novel biosensing tool. Upon transmission of a laser beam through a nanoparticle suspension in a pulsed magnetic field, the properties of the laser beam change. This can be detected by optical methods. Biomolecular binding events leading to aggregation of nanoparticles are ascertainable by calculating the relaxation time and from this, the hydrodynamic diameters of the involved particles from the optical signal. Interaction between insulin-like growth factor 1 (IGF-1) and its antibody was utilized for demonstration of the measurement setup applicability as an immunoassay. Furthermore, a formerly developed kinetic model was utilized in order to determine kinetic parameters of the interaction. Beside utilization of the method as an immunoassay it can be applied for the characterization of diverse magnetic nanoparticles regarding their size and size distribution. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessArticle Vehicle Based Laser Range Finding in Crops
Sensors 2009, 9(5), 3679-3694; doi:10.3390/s90503679
Received: 27 August 2008 / Accepted: 28 October 2008 / Published: 15 May 2009
Cited by 4 | PDF Full-text (1887 KB) | HTML Full-text | XML Full-text
Abstract
Laser rangefinders and laser scanners are widely used for industrial purposes and for remote sensing. In agriculture information about crop parameters like volume, height, and density can support the optimisation of production processes. In scientific papers the measurement of these parameters by low
[...] Read more.
Laser rangefinders and laser scanners are widely used for industrial purposes and for remote sensing. In agriculture information about crop parameters like volume, height, and density can support the optimisation of production processes. In scientific papers the measurement of these parameters by low cost laser rangefinders with one echo has been presented for short ranges. Because the cross section area of the beam increases with the measuring range, it can be expected that laser rangefinders will have a reduced measuring accuracy in small sized crops and when measuring far distances. These problems are caused by target areas smaller than the beam and by the beam striking the edges of crop objects. Lab tests under defined conditions and a real field test were performed to assess the measuring properties under such difficult conditions of a chosen low cost sensor. Based on lab tests it was shown that the accuracy was reduced, but the successful use of the sensor under field conditions demonstrated the potential to meet the demands for agricultural applications. Insights resulting from investigations made in the paper contribute to facilitating the choice or the development of laser rangefinder sensors for vehicle based measurement of crop parameters for optimisation of production processes. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessArticle Development of 3D Force Sensors for Nanopositioning and Nanomeasuring Machine
Sensors 2009, 9(5), 3228-3239; doi:10.3390/s90503228
Received: 3 April 2009 / Revised: 20 April 2009 / Accepted: 24 April 2009 / Published: 28 April 2009
Cited by 16 | PDF Full-text (359 KB) | HTML Full-text | XML Full-text
Abstract
In this contribution, we report on different miniaturized bulk micro machined three-axes piezoresistive force sensors for nanopositioning and nanomeasuring machine (NPMM). Various boss membrane structures, such as one boss full/cross, five boss full/cross and swastika membranes, were used as a basic structure for
[...] Read more.
In this contribution, we report on different miniaturized bulk micro machined three-axes piezoresistive force sensors for nanopositioning and nanomeasuring machine (NPMM). Various boss membrane structures, such as one boss full/cross, five boss full/cross and swastika membranes, were used as a basic structure for the force sensors. All designs have 16 p-type diffused piezoresistors on the surface of the membrane. Sensitivities in x, y and z directions are measured. Simulated and measured stiffness ratio in horizontal to vertical direction is measured for each design. Effect of the length of the stylus on H:V stiffness ratio is studied. Minimum and maximum deflection and resonance frequency are measured for all designs. The sensors were placed in a nanopositioning and nanomeasuring machine and one point measurements were performed for all the designs. Lastly the application of the sensor is shown, where dimension of a cube is measured using the sensor. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessArticle Heat Transfer Measurements with Surface Mounted Foil-Sensors in an Active Mode: A Comprehensive Review and a New Design
Sensors 2009, 9(4), 3011-3032; doi:10.3390/s90403011
Received: 23 March 2009 / Revised: 7 April 2009 / Accepted: 22 April 2009 / Published: 23 April 2009
Cited by 6 | PDF Full-text (443 KB) | HTML Full-text | XML Full-text
Abstract
A comprehensive review of film-sensors shows that they are primarily operated in a passive mode, i.e. without being actively heated to an extent, whereby they create a heat transfer situation on their own. Only when these sensors are used for wall shear stress
[...] Read more.
A comprehensive review of film-sensors shows that they are primarily operated in a passive mode, i.e. without being actively heated to an extent, whereby they create a heat transfer situation on their own. Only when these sensors are used for wall shear stress measurements, the detection of laminar/turbulent transition, or the measurement of certain flow velocities, they are operated in an active mode, i.e. heated by an electrical current (after an appropriate calibration). In our study we demonstrate how these R(T)-based sensors (temperature dependence of the electrical resistance R) can also be applied in an active mode for heat transfer measurements. These measurements can be made on cold, unheated bodies, provided certain requirements with respect to the flow field are fulfilled. Our new sensors are laminated nickel- and polyimide-foils manufactured with a special technology, which is also described in detail. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
Open AccessArticle New Dielectric Sensors and Sensing Techniques for Soil and Snow Moisture Measurements
Sensors 2009, 9(4), 2951-2967; doi:10.3390/s90402951
Received: 8 April 2009 / Revised: 17 April 2009 / Accepted: 22 April 2009 / Published: 22 April 2009
Cited by 13 | PDF Full-text (970 KB) | HTML Full-text | XML Full-text
Abstract
Measurements of material moisture are essential in fields such as agriculture or civil engineering. Electromagnetic techniques, more precisely dielectric methods, have gained wide acceptance in the last decades. Frequency or Time Domain methods take advantage of the high dielectric permittivity of water compared
[...] Read more.
Measurements of material moisture are essential in fields such as agriculture or civil engineering. Electromagnetic techniques, more precisely dielectric methods, have gained wide acceptance in the last decades. Frequency or Time Domain methods take advantage of the high dielectric permittivity of water compared to dry materials. This paper presents four new dielectric sensors for the determination of soil or snow water content. After a short introduction into the principles, both the hardware and operating mode of each sensor are described. Field test results show the advantages and potentials such as automatic measurement and profiling, state-of-ground detection or large-scale determination. From the results it follows that the presented sensors offer promising new tools for modern environmental research. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessArticle The Micro-Pillar Shear-Stress Sensor MPS3 for Turbulent Flow
Sensors 2009, 9(4), 2222-2251; doi:10.3390/s90402222
Received: 9 January 2009 / Revised: 25 March 2009 / Accepted: 26 March 2009 / Published: 30 March 2009
Cited by 14 | PDF Full-text (2700 KB) | HTML Full-text | XML Full-text
Abstract
Wall-shear stress results from the relative motion of a fluid over a body surface as a consequence of the no-slip condition of the fluid in the vicinity of the wall. To determine the two-dimensional wall-shear stress distribution is of utter importance in theoretical
[...] Read more.
Wall-shear stress results from the relative motion of a fluid over a body surface as a consequence of the no-slip condition of the fluid in the vicinity of the wall. To determine the two-dimensional wall-shear stress distribution is of utter importance in theoretical and applied turbulence research. In this article, characteristics of the Micro-Pillar Shear-Stress Sensor MPS3, which has been shown to offer the potential to measure the two-directional dynamic wall-shear stress distribution in turbulent flows, will be summarized. After a brief general description of the sensor concept, material characteristics, possible sensor-structure related error sources, various sensitivity and distinct sensor performance aspects will be addressed. Especially, pressure-sensitivity related aspects will be discussed. This discussion will serve as ‘design rules’ for possible new fields of applications of the sensor technology. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
Open AccessArticle Metal-Organic Frameworks for Sensing Applications in the Gas Phase
Sensors 2009, 9(3), 1574-1589; doi:10.3390/s90301574
Received: 19 February 2009 / Revised: 4 March 2009 / Accepted: 5 March 2009 / Published: 6 March 2009
Cited by 166 | PDF Full-text (329 KB) | HTML Full-text | XML Full-text
Abstract
Several metal-organic framework (MOF) materials were under investigated to test their applicability as sensor materials for impedimetric gas sensors. The materials were tested in a temperature range of 120 °C - 240 °C with varying concentrations of O2, CO2,
[...] Read more.
Several metal-organic framework (MOF) materials were under investigated to test their applicability as sensor materials for impedimetric gas sensors. The materials were tested in a temperature range of 120 °C - 240 °C with varying concentrations of O2, CO2, C3H8, NO, H2, ethanol and methanol in the gas atmosphere and under different test gas humidity conditions. Different sensor configurations were studied in a frequency range of 1 Hz -1 MHz and time-continuous measurements were performed at 1 Hz. The materials did not show any impedance response to O2, CO2, C3H8, NO, or H2 in the gas atmospheres, although for some materials a significant impedance decrease was induced by a change of the ethanol or methanol concentration in the gas phase. Moreover, pronounced promising and reversible changes in the electric properties of a special MOF material were monitored under varying humidity, with a linear response curve at 120 °C. Further investigations were carried out with differently doped MOF materials of this class, to evaluate the influence of special dopants on the sensor effect. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
Open AccessArticle Membrane Based Measurement Technology for in situ Monitoring of Gases in Soil
Sensors 2009, 9(2), 756-767; doi:10.3390/s90200756
Received: 23 September 2008 / Revised: 19 January 2009 / Accepted: 21 January 2009 / Published: 2 February 2009
Cited by 12 | PDF Full-text (594 KB) | HTML Full-text | XML Full-text
Abstract
The representative measurement of gas concentration and fluxes in heterogeneous soils is one of the current challenges when analyzing the interactions of biogeochemical processes in soils and global change. Furthermore, recent research projects on CO2-sequestration have an urgent need of CO
[...] Read more.
The representative measurement of gas concentration and fluxes in heterogeneous soils is one of the current challenges when analyzing the interactions of biogeochemical processes in soils and global change. Furthermore, recent research projects on CO2-sequestration have an urgent need of CO2-monitoring networks. Therefore, a measurement method based on selective permeation of gases through tubular membranes has been developed. Combining the specific permeation rates of gas components for a membrane and Dalton’s principle, the gas concentration (or partial pressure) can be determined by the measurement of physical quantities (pressure or volume) only. Due to the comparatively small permeation constants of membranes, the influence of the sensor on its surrounding area can be neglected. The design of the sensor membranes can be adapted to the spatial scale from the bench scale to the field scale. The sensitive area for the measurement can be optimized to obtain representative results. Furthermore, a continuous time-averaged measurement is possible where the time for averaging is simply controlled by the wall-thickness of the membrane used. The measuring method is demonstrated for continuous monitoring of O2 and CO2 inside of a sand filled Lysimeter. Using three sensor planes inside the sand pack, which were installed normal to the gas flow direction and a reference measurement system, we demonstrate the accuracy of the gas-detection for different flux-based boundary conditions. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
Open AccessArticle Zeolite-based Impedimetric Gas Sensor Device in Low-cost Technology for Hydrocarbon Gas Detection
Sensors 2008, 8(12), 7904-7916; doi:10.3390/s8127904
Received: 28 November 2008 / Revised: 4 December 2008 / Accepted: 4 December 2008 / Published: 5 December 2008
Cited by 23 | PDF Full-text (345 KB) | HTML Full-text | XML Full-text
Abstract
Due to increasing environmental concerns the need for inexpensive selective gas sensors is increasing. This work deals with transferring a novel zeolite-based impedimetric hydrocarbon gas sensor principle, which has been originally manufactured in a costly combination of photolithography, thin-film processes, and thick-film processes
[...] Read more.
Due to increasing environmental concerns the need for inexpensive selective gas sensors is increasing. This work deals with transferring a novel zeolite-based impedimetric hydrocarbon gas sensor principle, which has been originally manufactured in a costly combination of photolithography, thin-film processes, and thick-film processes to a lowcost technology comprising only thick-film processes and one electroplating step. The sensing effect is based on a thin chromium oxide layer between the interdigital electrodes and a Pt-loaded ZSM-5 zeolite film. When hydrocarbons are present in the sensor ambient, the electrical sensor impedance increases strongly and selectively. In the present work, the chromium oxide film is electroplated on Au screen-printed interdigital electrodes and then oxidized to Cr2O3. The electrode area is covered with the screen-printed zeolite. The sensor device is self-heated utilizing a planar platinum heater on the backside. The best sensor performance is obtained at a frequency of 3 Hz at around 350 °C. The good selectivity of the original sensor setup could be confirmed, but a strong cross-sensitivity to ammonia occurs, which might prohibit its original intention for use in automotive exhausts. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)

Review

Jump to: Research

Open AccessReview Metal Oxides and Ion-Exchanging Surfaces as pH Sensors in Liquids: State-of-the-Art and Outlook
Sensors 2009, 9(6), 4955-4985; doi:10.3390/s90604955
Received: 19 May 2009 / Revised: 14 June 2009 / Accepted: 16 June 2009 / Published: 23 June 2009
Cited by 57 | PDF Full-text (1272 KB) | HTML Full-text | XML Full-text
Abstract
Novel applications of online pH determinations at temperatures from -35 °C to 130 °C in technical and biological media, which are all but ideal aqueous solutions, require new approaches to pH monitoring. The glass electrode, introduced nearly hundred years ago, and
[...] Read more.
Novel applications of online pH determinations at temperatures from -35 °C to 130 °C in technical and biological media, which are all but ideal aqueous solutions, require new approaches to pH monitoring. The glass electrode, introduced nearly hundred years ago, and chemical sensors based on field effect transistors (ISFET) show specific drawbacks with respect to handling and long-time stability. Proton sensitive metal oxides seem to be a promising and alternative to the state-of-the-art measuring methods, and might overcome some problems of classical hydrogen electrodes and reference electrodes. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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Open AccessReview Solid State Gas Sensor Research in Germany – a Status Report
Sensors 2009, 9(6), 4323-4365; doi:10.3390/s90604323
Received: 25 March 2009 / Revised: 4 May 2009 / Accepted: 26 May 2009 / Published: 3 June 2009
Cited by 63 | PDF Full-text (1911 KB) | HTML Full-text | XML Full-text
Abstract
This status report overviews activities of the German gas sensor research community. It highlights recent progress in the field of potentiometric, amperometric, conductometric, impedimetric, and field effect-based gas sensors. It is shown that besides step-by-step improvements of conventional principles, e.g. by the application
[...] Read more.
This status report overviews activities of the German gas sensor research community. It highlights recent progress in the field of potentiometric, amperometric, conductometric, impedimetric, and field effect-based gas sensors. It is shown that besides step-by-step improvements of conventional principles, e.g. by the application of novel materials, novel principles turned out to enable new markets. In the field of mixed potential gas sensors, novel materials allow for selective detection of combustion exhaust components. The same goal can be reached by using zeolites for impedimetric gas sensors. Operando spectroscopy is a powerful tool to learn about the mechanisms in n-type and in p-type conductometric sensors and to design knowledge-based improved sensor devices. Novel deposition methods are applied to gain direct access to the material morphology as well as to obtain dense thick metal oxide films without high temperature steps. Since conductometric and impedimetric sensors have the disadvantage that a current has to pass the gas sensitive film, film morphology, electrode materials, and geometrical issues affect the sensor signal. Therefore, one tries to measure directly the Fermi level position either by measuring the gas-dependent Seebeck coefficient at high temperatures or at room temperature by applying a modified miniaturized Kelvin probe method, where surface adsorption-based work function changes drive the drain-source current of a field effect transistor. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
Open AccessReview Methodology and Significance of Microsensor-based Oxygen Mapping in Plant Seeds – an Overview
Sensors 2009, 9(5), 3218-3227; doi:10.3390/s90503218
Received: 17 March 2009 / Revised: 24 April 2009 / Accepted: 27 April 2009 / Published: 27 April 2009
Cited by 20 | PDF Full-text (857 KB) | HTML Full-text | XML Full-text
Abstract
Oxygen deficiency is commonplace in seeds, and limits both their development and their germination. It is, therefore, of considerable relevance to crop production. While the underlying physiological basis of seed hypoxia has been known for some time, the lack of any experimental means
[...] Read more.
Oxygen deficiency is commonplace in seeds, and limits both their development and their germination. It is, therefore, of considerable relevance to crop production. While the underlying physiological basis of seed hypoxia has been known for some time, the lack of any experimental means of measuring the global or localized oxygen concentration within the seed has hampered further progress in this research area. The development of oxygen-sensitive microsensors now offers the capability to determine the localized oxygen status within a seed, and to study its dynamic adjustment both to changes in the ambient environment, and to the seed's developmental stage. This review illustrates the use of oxygen microsensors in seed research, and presents an overview of existing data with an emphasis on crop species. Oxygen maps, both static and dynamic, should serve to increase our basic understanding of seed physiology, as well as to facilitate upcoming breeding and biotechnology-based approaches for crop improvement. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Germany)
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