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Sensor Element (sensor + element)

Distribution by Scientific Domains
Polymers and Materials Science40%

Selected Abstracts

Development of an oxide semiconductor thick film gas sensor for the detection of total volatile organic compounds

ELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 10 2010
Masahiro Kadosaki
Abstract Since the amendment of the Building Standards Law in 2003, the installation of ventilators is compulsory in newly built houses, because many persons suffer from indoor air pollution caused by volatile organic compounds (VOCs). The goal of this research is to develop a gas sensor that can monitor the total VOC (TVOC) gases indoors and then to control the ventilator efficiently using the sensor. In order to develop a sensor that detects TVOC, the responses of four oxide semiconductor materials to 37 different VOC gases were studied. These materials showed small responses to halogenated and aliphatic hydrocarbon gases. As a result of improving the response to these gases, among four metal oxides examined, SnO2 and WO3 showed high sensitivities by the addition of Pd and Pt. The sensing properties of SnO2 for halogenated hydrocarbon gases were greatly improved by the addition of 0.5 wt% Pd. The sensing properties of SnO2 for aliphatic hydrocarbon gases were improved by the addition of 0.7 wt% Pt. In addition, a sensor element with the addition of both platinum and palladium, that is, Pt (0.5 wt%)-Pd (0.5 wt%)-SnO2, showed a large response to many of the VOC gases examined. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(10): 34,41, 2010; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10190 [source]

Solid-State SO2 Sensor Using a Sodium-Ionic Conductor and a Metal,Sulfide Electrode

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2006
Youichi Shimizu
All solid-state sulfur oxides (SOx) sensor devices combined with a sodium ionic conductor (Na5DySi4O12) disk and metal sulfide-sensing electrodes synthesized via solution routes have been systematically investigated for the detection of SO2 in the range of 20,200 ppm at 150,400°C. Among the various sulfide-sensing electrodes tested, the metal monosulfide-based electrodes gave good SO2 sensitivity at 400°C. The Pb1,xCdxS (x=0.1, 0.2)-based solid electrolyte sensor element showed the best sensing characteristics, i.e., the EMF response was almost linear to the logarithm of SO2 concentration in the range between 40 and 400 ppm, with a 90% response time to 100 ppm SO2 of about 3,15 min, and also showed high selectivity to SO2 at 400°C. [source]

Microstructure and humidity sensitive properties of MgFe2O4 ferrite with Ni and Mn substitutions

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004
E. Rezlescu
Abstract It was studied the effect of manganese and nickel ions on the microstructure and humidity sensitivity of the electrical resistivity of Mg ferrite. The humidity sensitivity depends on composition. The MgMn0.2Fe1.8O4 is sensitive in a wide humidity range, between 11% and 85%RH. The other compositions are sensitive at high humidities only, between 43% and 98%. The response time of a.c. resistivity to the humidity variations was measured to be about 120 seconds for all compositions. This sensor element can be used for controlling the humidity in microwave ovens. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Gas sensing in microplates with optodes: Influence of oxygen exchange between sample, air, and plate material

BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2005
Sarina Arain
Abstract Microplates with integrated optical oxygen sensors are a new tool to study metabolic rates and enzyme activities. Precise measurements are possible only if oxygen exchange between the sample and the environment is known. In this study we quantify gas exchange in plastic microplates. Dissolved oxygen was detected using either an oxygen-sensitive film fixed at the bottom of each well or a needle-type sensor. The diffusion of oxygen into wells sealed with different foils, paraffin oil, and paraffin wax, respectively, was quantified. Although foil covers showed the lowest oxygen permeability, they include an inevitable gas phase between sample and sealing and are difficult to manage. The use of oil was found to be critical due to the extensive shaking caused by movement of the plates during measurements in microplate readers. Thus, paraffin wax was the choice material because it avoids convection of the sample and is easy to handle. Furthermore, without shaking, significant gradients in pO2 levels within a single well of a polystyrene microplate covered with paraffin oil were detected with the needle-type sensor. Higher pO2 levels were obtained near the surface of the sample as well as near the wall of the well. A significant diffusion of oxygen through the plastic plate material was found using plates based on polystyrene. Thus, the location of a sensor element within the well has an effect on the measured pO2 level. Using a sensor film fixed on the bottom of a well or using a dissolved pO2 -sensitive indicator results in pO2 offset and in apparently lower respiration rates or enzyme activities. Oxygen diffusion through a polystyrene microplate was simulated for measurements without convection,that is, for samples without oxygen diffusion through the cover and for unshaken measurements using permeable sealings. This mathematical model allows for calculation of the correct kinetic parameters. © 2005 Wiley Periodicals, Inc. [source]

Porous Silicon-Based Optical Microsensors for Volatile Organic Analytes: Effect of Surface Chemistry on Stability and Specificity

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Anne M. Ruminski
Abstract Sensing of the volatile organic compounds (VOCs) isopropyl alcohol (IPA) and heptane in air using sub-millimeter porous silicon-based sensor elements is demonstrated in the concentration range 50,800 ppm. The sensor elements are prepared as one-dimensional photonic crystals (rugate filters) by programmed electrochemical etch of p++ silicon, and analyte sensing is achieved by measurement of the wavelength shift of the photonic resonance. The sensors are studied as a function of surface chemistry: ozone oxidation, thermal oxidation, hydrosilylation (1-dodecene), electrochemical methylation, reaction with dicholorodimethylsilane and thermal carbonization with acetylene. The thermally oxidized and the dichlorodimethylsilane-modified materials show the greatest stability under atmospheric conditions. Optical microsensors are prepared by attachment of the porous Si layer to the distal end of optical fibers. The acetylated porous Si microsensor displays a greater response to heptane than to IPA, whereas the other chemical modifications display a greater response to IPA than to heptane. The thermal oxide sensor displays a strong response to water vapor, while the acetylated material shows a relatively weak response. The results suggest that a combination of optical fiber sensors with different surface chemistries can be used to classify VOC analytes. Application of the miniature sensors to the detection of VOC breakthrough in a full-scale activated carbon respirator cartridge simulator is demonstrated. [source]