bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Sensing Properties of Ordered Mesoporous SnO2
Authors: Wagner Thorsten , Kohl Claus-Dieter , Fröba Michael , Tiemann Michael
Published: October 2008

We report on the synthesis and CO gas-sensing properties of mesoporoustin(IV) oxides (SnO2). For the synthesis cetyltrimethylammonium bromide (CTABr) wasused as a structure-directing agent; the resulting SnO2 powders were applied as films tocommercially available sensor substrates by drop coating. Nitrogen physisorption showsspecific surface areas up to 160 m2·g-1 and mean pore diameters of about 4 nm, as verifiedby TEM. The film conductance was measured in dependence on the CO concentration inhumid synthetic air at a constant temperature of 300 °C. The sensors show a high sensitivityat low CO concentrations and turn out to be largely insensitive towards changes in therelative humidity. We compare the materials with commercially available SnO2-basedsensors.
Quartz Crystal Nanobalance in Conjunction with Principal Component Analysis for Identification of Volatile Organic Compounds
Authors: Mirmohseni Abdolreza , Rostamizadeh Kobra
Published: October 2008

Quartz crystal nanobalance (QCN) sensors are considered as powerful mass-sensitive sensors to determine materials in the sub-nanogram level. In this study, a singlepiezoelectric quartz crystal nanobalance modified with polystyrene was employed to detectbenzene, toluene, ethylbenzene and xylene (BTEX compounds). The frequency shift of theQCN sensor was found to be linear against the BTEX compound concentrations in the rangeabout 1-45 mg l-1. The correlation coefficients for benzene, toluene, ethylbenzene, andxylene were 0.991, 0.9977, 0.9946 and 0.9971, respectively. The principal componentanalysis was also utilized to process the frequency response data of the single piezoelectriccrystal at different times, considering to the different adsorption-desorption dynamics ofBTEX compounds. Using principal component analysis, it was found that over 90% of thedata variance could still be explained by use of two principal components (PC1 and PC2).Subsequently, the successful identification of benzene and toluene was possible through theprincipal component analysis of the transient responses of the polystyrene modified QCNsensor. The results showed that the polystyrene-modified QCN had favorable identificationand quantification performances for the BTEX compounds.
High Frequency Quartz Micro Balances: A Promising Path to Enhanced Sensitivity of Gravimetric Sensors
Authors: Kreutz Chrisitan , Lörgen Jürgen , Graewe Boris , Bargon Joachim , Yoshida Mayumi , Fresco Zachary  M. , Frèchet Jean  M.J.
Published: October 2008

An array of 50 MHz quartz microbalances (QMBs) coated with a dendronizedpolymer was used to detect small amounts of volatile organic compounds (VOCs) in the gasphase. The results were compared to those obtained with the commonly used 10 MHzQMBs. The 50 MHz QMBs proved to be a powerful tool for the detection of VOCs in thegas phase; therefore, they represent a promising alternative to the much more delicatesurface acoustic wave devices (SAWs).
A Concept for a Sensitive Micro Total Analysis System for High Throughput Fluorescence Imaging
Authors: Rabner Arthur , Shacham Yosi
Published: October 2008

This paper discusses possible methods for on-chip fluorescent imaging forintegrated bio-sensors. The integration of optical and electro-optical accessories, accordingto suggested methods, can improve the performance of fluorescence imaging. It can boostthe signal to background ratio by a few orders of magnitudes in comparison to conventionaldiscrete setups. The methods that are present in this paper are oriented towards buildingreproducible arrays for high-throughput micro total analysis systems (μTAS). The firstmethod relates to side illumination of the fluorescent material placed into micro-compartments of the lab-on-chip. Its significance is in high utilization of excitation energyfor low concentration of fluorescent material. The utilization of a transparent μLED chip,for the second method, allows the placement of the excitation light sources on the sameoptical axis with emission detector, such that the excitation and emission rays are directedcontroversly. The third method presents a spatial filtering of the excitation background.
Fabrication and Characterisation of GaAs Gunn Diode Chips for Applications at 77 GHz in Automotive Industry
Authors: Förster Arno , Stock Jürgen , Montanari Simone , Lepsa Mihail  Ion , Lüth Hans
Published: October 2008

GaAs-based Gunn diodes with graded AlGaAs hot electron injectorheterostructures have been developed under the special needs in automotive applications.The fabrication of the Gunn diode chips was based on total substrate removal andprocessing of integrated Au heat sinks. Especially, the thermal and RF behavior of thediodes have been analyzed by DC, impedance and S-parameter measurements. Theelectrical investigations have revealed the functionality of the hot electron injector. Anoptimized layer structure could fulfill the requirements in adaptive cruise control (ACC)systems at 77 GHz with typical output power between 50 and 90 mW.
“Microstructured Nanostructures” – Nanostructuring by Means of Conventional Photolithography and Layer-expansion Technique
Authors: Platen Johannes , Poghossian Arshak , Schöning Michael J.
Published: October 2008

A new and simple method for nanostructuring using conventionalphotolithography and layer expansion or pattern-size reduction technique is presented, whichcan further be applied for the fabrication of different nanostructures and nano-devices. Themethod is based on the conversion of a photolithographically patterned metal layer to ametal-oxide mask with improved pattern-size resolution using thermal oxidation. With thistechnique, the pattern size can be scaled down to several nanometer dimensions. Theproposed method is experimentally demonstrated by preparing nanostructures with differentconfigurations and layouts, like circles, rectangles, trapezoids, “fluidic-channel”-,“cantilever”- and meander-type structures.
Surface Modification for Microreactor Fabrication
Authors: Pijanowska Dorota  G. , Remiszewska Elżbieta , Pederzolli Cecilia , Lunelli Lorenzo , Vendano Michele , Canteri Roberto , Dudziński Konrad , Kruk Jerzy , Torbicz Wladyslaw
Published: October 2008

In this paper, methods of surface modification of different supports, i.e. glass andpolymeric beads for enzyme immobilisation are described. The developed method ofenzyme immobilisation is based on Schiff’s base formation between the amino groups onthe enzyme surface and the aldehyde groups on the chemically modified surface of thesupports. The surface of silicon modified by APTS and GOPS with immobilised enzymewas characterised by atomic force microscopy (AFM), time-of-flight secondary ion massspectroscopy (ToF-SIMS) and infrared spectroscopy (FTIR). The supports withimmobilised enzyme (urease) were also tested in combination with microreactors fabricatedin silicon and Perspex, operating in a flow-through system. For microreactors filled withurease immobilised on glass beads (Sigma) and on polymeric beads (PAN), a very high andstable signal (pH change) was obtained. The developed method of urease immobilisationcan be stated to be very effective.
Miniaturized, Planar Ion-selective Electrodes Fabricated by Means of Thick-film Technology
Authors: Tymecki Lukasz , Glab Stanisław , Koncki Robert
Published: October 2008

Various planar technologies are employed for developing solid-state sensorshaving low cost, small size and high reproducibility; thin- and thick-film technologies aremost suitable for such productions. Screen-printing is especially suitable due to itssimplicity, low-cost, high reproducibility and efficiency in large-scale production. Thistechnology enables the deposition of a thick layer and allows precise pattern control.Moreover, this is a highly economic technology, saving large amounts of the used inks. Inthe course of repetitions of the film-deposition procedure there is no waste of material dueto additivity of this thick-film technology. Finally, the thick films can be easily and quicklydeposited on inexpensive substrates. In this contribution, thick-film ion-selective electrodesbased on ionophores as well as crystalline ion-selective materials dedicated forpotentiometric measurements are demonstrated. Analytical parameters of these sensors arecomparable with those reported for conventional potentiometric electrodes. All mentionedthick-film strip electrodes have been totally fabricated in only one, fully automated thick-film technology, without any additional manual, chemical or electrochemical steps. In allcases simple, inexpensive, commercially available materials, i.e. flexible, plastic substratesand easily cured polymer-based pastes were used.
Functional Testing and Characterisation of ISFETs on Wafer Level by Means of a Micro-droplet Cell
Authors: Poghossian Arshak , Schumacher Kerstin , Kloock Joachim  P. , Rosenkranz Christian , Schultze Joachim  W. , Müller-Veggian Mattea , Schöning Michael J.
Published: October 2008

A wafer-level functionality testing and characterisation system for ISFETs (ion-sensitive field-effect transistor) is realised by means of integration of a specifically designedcapillary electrochemical micro-droplet cell into a commercial wafer prober-station. Thedeveloped system allows the identification and selection of “good” ISFETs at the earlieststage and to avoid expensive bonding, encapsulation and packaging processes for non-functioning ISFETs and thus, to decrease costs, which are wasted for bad dies. Thedeveloped system is also feasible for wafer-level characterisation of ISFETs in terms ofsensitivity, hysteresis and response time. Additionally, the system might be also utilised forwafer-level testing of further electrochemical sensors.
High-temperature MEMS Heater Platforms: Long-term Performance of Metal and Semiconductor Heater Materials
Authors: Spannhake Jan , Schulz Olaf , Helwig Andreas , Krenkow Angelika , Müller Gerhard , Doll Theodor
Published: October 2008

Micromachined thermal heater platforms offer low electrical power consumptionand high modulation speed, i.e. properties which are advantageous for realizing non-dispersive infrared (NDIR) gas- and liquid monitoring systems. In this paper, we report oninvestigations on silicon-on-insulator (SOI) based infrared (IR) emitter devices heated byemploying different kinds of metallic and semiconductor heater materials. Our resultsclearly reveal the superior high-temperature performance of semiconductor over metallicheater materials. Long-term stable emitter operation in the vicinity of 1300 K could beattained using heavily antimony-doped tin dioxide (SnO2:Sb) heater elements.
Magneto-controlled Quantized Electron Transfer to Surface-confined Redox Units and Metal Nanoparticles
Authors: Katz Eugenii , Willner Itamar
Published: October 2008

Hydrophobic magnetic nanoparticles (NPs) consisting of undecanoate-cappedmagnetite (Fe3O4, average diameter ca. 5 nm) are used to control quantized electron transferto surface-confined redox units and metal NPs. A two-phase system consisting of anaqueous electrolyte solution and a toluene phase that includes the suspended undecanoate-capped magnetic NPs is used to control the interfacial properties of the electrode surface.The attracted magnetic NPs form a hydrophobic layer on the electrode surface resulting inthe change of the mechanisms of the surface-confined electrochemical processes. Aquinone-monolayer modified Au electrode demonstrates an aqueous-type of theelectrochemical process (2e- 2H+ redox mechanism) for the quinone units in the absence ofthe hydrophobic magnetic NPs, while the attraction of the magnetic NPs to the surfaceresults in the stepwise single-electron transfer mechanism characteristic of a dry non-aqueous medium. Also, the attraction of the hydrophobic magnetic NPs to the Au electrodesurface modified with Au NPs (ca. 1.4 nm) yields a microenvironment with a low dielectricconstant that results in the single-electron quantum charging of the Au NPs.
pH-based Detection of Phenylalnine by Potentiometric and Colorimetric Methods
Authors: Pijanowska Dorota  G. , Remiszewska Elżbieta
Published: October 2008

In this paper, methods of sample preparation for potentiometric measurement ofphenylalanine are presented. Basing on the spectrophotometric measurements ofphenylalanine, the concentrations of reagents of the enzymatic reaction (10 mM L-Phe,0,4 mM NAD+ , 2U L-PheDH) were determined. Then, the absorption spectrum of thereaction product, NADH, was monitored (maximum peak at 340 nm). The results obtainedby the spectrophotometric method were compared with the results obtained by thecolourimetry, using pH indicators. The above-mentioned two methods will be used asreferences for potentiometric measurements of phenylalanine concentration.
Novel Organic Membrane-based Thin-film Microsensors for the Determination of Heavy Metal Cations
Authors: Arida Hassan  A. , Kloock Joachim  P. , Schöning Michael  J.
Published: October 2008

A first step towards the fabrication and electrochemical evaluation of thin-filmmicrosensors based on organic PVC membranes for the determination of Hg(II), Cd(II),Pb(II) and Cu(II) ions in solutions has been realised. The membrane-coating mixture used inthe preparation of this new type of microsensors is incorporating PVC as supporting matrix,o-nitrophenyloctylether (o-NPOE) as solvent mediator and a recently synthesizedHg[dimethylglyoxime(phene)]2+ and Bis-(4-hydroxyacetophenone)-ethylenediamine aselectroactive materials for Hg(II) and Cd(II), respectively. A set of three commercialisedionophores for Cd(II), Pb(II) and Cu(II) has been also used for comparison. Thin-filmmicrosensors based on these membranes showed a Nernstian response of slope(26-30 mV/dec.) for the respective tested cations. The potentiometric responsecharacteristics (linear range, pH range, detection limit and response time) are comparablewith those obtained by conventional membranes as well as coated wire electrodes preparedfrom the same membrane. The realisation of the new organic membrane-based thin-filmmicrosensors overcomes the problem of an insufficient selectivity of solid-state-based thin-film sensors.
Silver Solid Amalgam Electrodes as Sensors for Chemical Carcinogens
Authors: Barek Jiri , Fischer Jan , Navratil Tomas , Peckova Karolina , Yosypchuk Bogdan
Published: October 2008

The applicability of differential pulse voltammetry (DPV) and adsorptivestripping voltammetry (AdSV) at a non-toxic meniscus-modified silver solid amalgamelectrode (m-AgSAE) for the determination of trace amounts of genotoxic substances wasdemonstrated on the determination of micromolar and submicromolar concentrations of3-nitrofluoranthene using methanol - 0.01 mol L-1 NaOH (9:1) mixture as a base electrolyteand of Ostazine Orange using 0.01 mol L-1 NaOH as a base electrolyte.
Mathematical Modeling of Biosensors Based on an Array of Enzyme Microreactors
Authors: Baronas Romas , Ivanauskas Feliksas , Kulys Juozas
Published: October 2008

This paper presents a two-dimensional-in-space mathematical model ofbiosensors based on an array of enzyme microreactors immobilised on a single electrode.The modeling system acts under amperometric conditions. The microreactors were modeledby particles and by strips. The model is based on the diffusion equations containing a non-linear term related to the Michaelis-Menten kinetics of the enzymatic reaction. The modelinvolves three regions: an array of enzyme microreactors where enzyme reaction as well asmass transport by diffusion takes place, a diffusion limiting region where only the diffusiontakes place, and a convective region, where the analyte concentration is maintained constant.Using computer simulation, the influence of the geometry of the microreactors and of thediffusion region on the biosensor response was investigated. The digital simulation wascarried out using the finite difference technique.
Biosensor for Direct Determination of Fenitrothion and EPN Using Recombinant Pseudomonas putida JS444 with Surface Expressed Organophosphorus Hydrolase. 1. Modified Clark Oxygen Electrode
Authors: Lei Yu , Mulchandani Priti , Chen Wilfred , Mulchandani Ashok
Published: October 2008

This paper reports a first microbial biosensor for rapid and cost-effectivedetermination of organophosphorus pesticides fenitrothion and EPN. The biosensorconsisted of recombinant PNP-degrading/oxidizing bacteria Pseudomonas putida JS444anchoring and displaying organophosphorus hydrolase (OPH) on its cell surface asbiological sensing element and a dissolved oxygen electrode as the transducer. Surface-expressed OPH catalyzed the hydrolysis of fenitrothion and EPN to release 3-methyl-4-nitrophenol and p-nitrophenol, respectively, which were oxidized by the enzymaticmachinery of Pseudomonas putida JS444 to carbon dioxide while consuming oxygen,which was measured and correlated to the concentration of organophosphates. Under theoptimum operating conditions, the biosensor was able to measure as low as 277 ppb offenitrothion and 1.6 ppm of EPN without interference from phenolic compounds and othercommonly used pesticides such as carbamate pesticides, triazine herbicides andorganophosphate pesticides without nitrophenyl substituent. The applicability of thebiosensor to lake water was also demonstrated.
Simulation Study of Nano Aqueous Flow Sensor Based on Amperometric Measurement
Authors: Wu Jian , Zhou Qingli , Liu Jun , Lou Zhengguo
Published: October 2008

In this paper, a novel nano aqueous flow sensor which consists of two closelyspaced amperometric sensors is investigated by digital simulation. The simulation resultsindicate that the ratio of the responses of two closely spaced amperometric sensors is onlyrelated to flow rates in the channel, insensitive to the analyte concentration in the solution.By comparing the output of two amperometric sensors, the flow rate in the channel can bededuced. It is not necessary to determine the analyte concentration in advance. Thesimulation results show it is able to detect flow rate by in the range of several nano-liters perminute when the distance between the working electrodes of two amperometric sensors is200 nm and the cross-section of the channel is 1 μm x 1 μm.
An Ion-selective Electrode for Anion Perchlorate in Thick-film Technology
Authors: Segui María  Jesús , Lizondo-Sabater Josefa , Martínez-Máñez Ramón , Sancenón Félix , Soto Juan , García-Breijo Eduardo , Gil Luís
Published: October 2008

The ionophore 1,4,7,10,13-penta(n-octyl)-1,4,7,10,13-pentaazacyclopentadecane(L1) was used for the development of miniaturised perchlorate-selective electrodes in thick-film technology. Different PVC membranes containing L1 and the plasticizers o-nitrophenyloctyl ether (NPOE), dibutyl phthalate (DBP), bis(2-ethylhexyl)sebacate (DOS) and dibutylsebacate (DBS) were prepared and placed on a graphite working electrode manufactured byusing thick film serigraphic technology. The perchlorate selective electrode containing DBSas plasticizer showed a potentiometric Nernstian response of -57 mV per decade in a rangeof perchlorate concentration from 1 x 10-4 to 1 x 10-1 M with a detection limit of 5 x 10-5 M.The ion selective electrodes containing DBP and NPOE as plasticizers exhibit a workingrange from 6.3 x 10-5 to 1 x 10-1 M and 7.4 x 10-5 to 1 x 10-1 M for perchlorate, respectively,with a detection limit of ca. 2.2 x 10-5 M. For all three electrodes a response time of ca. 5 s was found. The prepared electrodes do not show appreciable decay of the slope for at least 25 days. Potentiometric selectivity coefficients (log KpotClO4-,X-) with respect to the primaryanion perchlorate were evaluated using the fixed interference method. These coefficients areof the order of 10-1.7 or smaller, indicating the relatively poor interference of the differentanions studied.
Enhancement of H2-sensing Properties of F-doped SnO2 Sensorby Surface Modification with SiO2
Authors: Han Chi-Hwan , Han Sang-Do , Khatkar S. P.
Published: October 2008

Effects of surface chemical modification with sodium silicate on the gas-sensingproperties of F-doped SnO2 gas sensor designed and fabricated employing micro-electromechanical system (MEMS) technology were investigated. Gas sensing properties of thesensor were checked against combustible gases like H2, CO, CH4 and C3H8 at a heatervoltage of 0.7 V. The H2 sensitivity of the surface modified F-doped SnO2 micro sensormarkedly increased and reached S = 175 which was found to be about 40 times more thanthat of unmodified sensor (S = ~ 4.2). The increase in the sensitivity is discussed in terms ofincreased resistivity and reduced permeation of gaseous oxygen into the underlying sensinglayer due to the surface modification of the sensor. The present micro-hydrogen sensor withenhanced sensitivity due to SiO2 incorporation is a low energy consuming portable sensormodule that can be mass-produced using MEMS technology at low cost.
CNT Sensors for Detecting Gases with Low Adsorption Energy by Ionization
Authors: Kim Seongjeen
Published: October 2008

In case of typical chemical gas sensors reacted by gas adsorption on surface of anactive layer, it is difficult to detect some gases which have low chemical adsorption energylike inert gases. In this paper, we report a gas sensor using carbon nanotube(CNT) array aselectron emitters for the purpose of detecting these gases. Specifically, sensors werefabricated with applications of glass patterning by a sand-blast process and of anodicbonding between glass and silicon to improve the compactness of the structure and thereliability in process. The proposed sensor, based on an electrical discharge theory known asPaschen's law, worked by figuring the changes of dark discharge current and initialbreakdown voltage depending on the concentration and the identity of gases. In this work,air and Ar gases were examined and discussed.
Light Dependent Resistance as a Sensor in Spectroscopy Setups Using Pulsed Light and Compared with Electret Microphones
Authors: Da Silva Derci  Felix , Acosta-Avalos Daniel
Published: October 2008

Light-dependent resistances (LDR) are cheap light sensors. A less known lightdetector is the electret microphone, whose electret membrane functions as a perfectabsorber, but only detects pulsed light. The aim of this study was to analyze the use of aLDR and an electret microphone as a light sensor in an optical spectroscopy system usingpulsed light. A photoacoustic spectroscopy setup was used, substituting the photoacousticchamber by the light sensor proposed. The absorption spectra of two different liquids wereanalyzed. The results obtained allow the recommendation of the LDR as the first choice inthe construction of cheap homemade pulsed light spectroscopy systems.
Micro Semiconductor CO Sensors Based on Indium-Doped Tin Dioxide Nanocrystalline Powders
Authors: Kim Il Jin , Han Sang Do , Han Chi Hwan , Gwak Jihye , Lee Hi Doek , Wang Jin Suk
Published: October 2008

The precursors of SnO2 or In2O3/SnO2 nanocrystlline powders have been prepared bythe sol-precipitation method. The precursors were calcined at different temperatures to prepareSnO2 or In2O3/SnO2 nanocrystalline powders with different particle sizes. The nanocrystalliteswere examined by differential thermal analysis (DTA), X-ray diffraction (XRD) andtransmission electron microscopy (TEM). And then thick film CO sensors were fabricated usingprepared SnO2 or In2O3/SnO2 nanocrystlline powders loaded with PdOx. The composition thatgave the highest sensitivity for CO was in the weight% ratio of 5 wt.% In2O3/SnO2:PdOx as99:1(wt %). The composite material was found sensitive against CO at the working temperature200 °C. It was found that the sensors based on In2O3/SnO2 nanocrystalline system exhibitedvery short response time to CO at ppm level. These characteristics make the sensor to be apromising candidate for detecting low concentrations of CO.
Reticulation of Aqueous Polyurethane Systems Controlled by DSC Method
Authors: Cakic Suzana , Lacnjevac Caslav , Rajkovic Milos   B. , Raskovic Ljiljana , Stamenkovic Jakov
Published: October 2008

The DSC method has been employed to monitor the kinetics of reticulation ofaqueous polyurethane systems without catalysts, and with the commercial catalyst of zirconium(CAT®XC-6212) and the highly selective manganese catalyst, the complex Mn(III)-diacetylacetonemaleinate (MAM). Among the polyol components, the acrylic emulsions wereused for reticulation in this research, and as suitable reticulation agents the water emulsiblealiphatic polyisocyanates based on hexamethylendoisocyanate with the different contents ofNCO-groups were employed. On the basis of DSC analysis, applying the methods of Kissinger,Freeman-Carroll and Crane-Ellerstein the pseudo kinetic parameters of the reticulation reactionof aqueous systems were determined. The temperature of the examination ranged from 50oC to450oC with the heat rate of 0.5oC/min. The reduction of the activation energy and the increaseof the standard deviation indicate the catalytic action of the selective catalysts of zirconium andmanganese. The impact of the catalysts on the reduction of the activation energy is thestrongest when using the catalysts of manganese and applying all the three afore-said methods.The least aberrations among the stated methods in defining the kinetic parameters wereobtained by using the manganese catalyst.
Differential Laser Doppler based Non-Contact Sensor for Dimensional Inspection with Error Propagation Evaluation
Authors: Mekid Samir , Vacharanukul Ketsaya
Published: October 2008

To achieve dynamic error compensation in CNC machine tools, a non-contactlaser probe capable of dimensional measurement of a workpiece while it is being machinedhas been developed and presented in this paper. The measurements are automatically fedback to the machine controller for intelligent error compensations. Based on a well resolvedlaser Doppler technique and real time data acquisition, the probe delivers a very promisingdimensional accuracy at few microns over a range of 100 mm. The developed opticalmeasuring apparatus employs a differential laser Doppler arrangement allowing acquisitionof information from the workpiece surface. In addition, the measurements are traceable tostandards of frequency allowing higher precision.
Further Structural Intelligence for Sensors Cluster Technology in Manufacturing
Authors: Mekid Samir
Published: October 2008

With the ever increasing complex sensing and actuating tasks in manufacturingplants, intelligent sensors cluster in hybrid networks becomes a rapidly expanding area.They play a dominant role in many fields from macro and micro scale. Global object controland the ability to self organize into fault-tolerant and scalable systems are expected for highlevel applications. In this paper, new structural concepts of intelligent sensors and networkswith new intelligent agents are presented. Embedding new functionalities to dynamicallymanage cooperative agents for autonomous machines are interesting key enablingtechnologies most required in manufacturing for zero defects production.
Development of an In-Fiber Nanocavity Towards Detection of Volatile Organic Gases
Authors: Elosua Cesar , Matias Ignacio R. , Bariain Candido , Arregui Francisco J.
Published: October 2008

A fiber optic sensor for Volatile Organic Compounds (VOCs) detection has beendeveloped and characterized for some organic gasses. The sensor is based on a novelvapochromic material, which is able to change its optical properties in presence of organicvapors in a reversely way. A nano Fabry Perot is constructed onto a cleaved ended opticalfiber pigtail by Electrostatic Self Assembly method (ESA), doping this structure with thevapochromic material. Employing a reflection scheme, a change in the intensity modulatedreflected signal at 850 nm have been registered. The response of the sensor has beenevaluated for five different VOCs, and a deeper study has been made for vapors of threedifferent alcohols.
Cyclodextrin Derivatives as Chiral Supramolecular Receptors for Enantioselective Sensing
Authors: Shahgaldian Patrick , Pieles Uwe
Published: October 2008

In view of the chiral nature of many bio-molecules (and all bio-macromolecules),most of therapeutically active compounds which target these molecules need to be chiraland “good handed” to be effective. In addition to asymmetric synthetic and separationmethodologies, enantioselective chemical sensors, able to distinguish between twoenantiomers of the same molecule, are of relevance. In order to design these sensing tools,two major classes of enantioselective layers have been developed. The first is based onmolecularly imprinted polymers which are produced (polymerized) in the presence of theirtarget, thus the polymeric material keep in “memory” the size and the shape of this moleculeand the system could be used for sensing (not reviewed here). The second approach makesuse of sensitive layers containing chiral macrocyclic receptors able of stereoselectivemolecular recognition; these receptors are mainly based on cyclodextrins. In thiscontribution, are reviewed achievements in the use of native or chemically modifiedcyclodextrins for chiral sensing purposes (at interfaces). Potentialities of other chiralmacrocycles based on calixarenes, calix-resorcinarenes or crown-ethers as supramolecularreceptors for enantioselective sensing are discussed.
Introduction to the Special Issue on "Satellite Altimetry: New Sensors and New Applications"
Authors: Quartly Graham , Chen Ge
Published: October 2008

Spaceborne radar altimeters provide information on the Earth's surface by transmitting a series of radio-frequency pulses and recording their echoes.[...]
A Rotating Knife-beam Altimeter for Wide-swath Remote Sensing of Ocean: Wind and Waves
Authors: Karaev V. Yu. , Kanevsky M. B. , Balandina G. N. , Meshkov E. M. , Challenor P. , Srokosz Meric , Gommenginger C.
Published: October 2008

The use of a nadir altimeter radar with a rotating knife-beam antenna pattern isconsidered for improved measurements of the sea surface wind and wave parameters over awide swath. Theoretical calculations suggest the antenna beam rotating about the verticalaxis is able to provide wide swath of order 250-350 km. Processing of the signals using timeor Doppler sampling techniques results in the division of the antenna footprint intoelementary scattering cells of the order of 14x14 km. The theoretical algorithms developedhere indicate that the system may be used to retrieve the variance of large-scale slopes, thedirection of wave propagation and the wind speed in each cell. The possibility of measuringsignificant wave height is also analyzed. The combination of linear motion of the radar andthe rotation of the knife-beam antenna can be exploited to build up a two-dimensional mapof the surface, which enables better understanding of wave processes and to study theirstructure and temporal dynamics using repeated observations.
Wide Bandgap Semiconductor Nanorod and Thin Film Gas Sensors
Authors: Kang Byoung Sam , Wang Hung-Ta , Tien Li- Chia , Ren Fan , Gila Brent P. , Norton David P. , Abernathy Cammy R. , Lin Jenshan , Pearton Stepehn J.
Published: October 2008

In this review we discuss the advances in use of GaN and ZnO-based solid-statesensors for gas sensing applications. AlGaN/GaN high electron mobility transistors(HEMTs) show a strong dependence of source/drain current on the piezoelectricpolarization -induced two dimensional electron gas (2DEG). Furthermore, spontaneous andpiezoelectric polarization induced surface and interface charges can be used to develop verysensitive but robust sensors for the detection of gases. Pt-gated GaN Schottky diodes and Sc2O3/AlGaN/GaN metal-oxide semiconductor diodes also show large change in forwardcurrents upon exposure to H2 containing ambients. Of particular interest are methods fordetecting ethylene (C2H4), which offers problems because of its strong double bonds andhence the difficulty in dissociating it at modest temperatures. ZnO nanorods offer largesurface area, are bio-safe and offer excellent gas sensing characteristics.
Sensing Arrays Constructed from Nanoparticle Thin Films and Interdigitated Microelectrodes
Authors: Wang Lingyan , Kariuki Nancy  N. , Schadt Mark , Mott Derrick , Luo Jin , Zhong Chuan-Jian , Shi Xiajing , Zhang Chen , Hao Weibing , Lu Susan , Kim Nam , Wang Jian-Q.
Published: October 2008

This paper describes the results of a study of a few design parameters influencingthe performance of sensor arrays constructed from nanostructured thin films andinterdigitated microelectrodes (IMEs). The nanostructured thin films on the IME deviceswere prepared from nonanedithiol (NDT) and mercaptoundecanoic acid (MUA) linkedassemblies of 2-nm sized gold nanoparticles. The sensor array data in response to volatileorganic compounds were collected and analyzed using fractional factorial experimentaldesign and analysis of variance for understanding effects of the design parameters on thesensitivity. While the smaller value for the microelectrode space, width, and lengthgenerally led to higher response sensitivity, a strong dependence on the nature of thenanostructured thin films was found. The microelectrode space was the most importantdesign parameter for NDT-based thin films. However, the microelectrode space, width, andlength were found to play almost equally important roles for MUA-based thin films. Theprincipal component analysis results for classification performances of the arrays consistingof a set of thin films have demonstrated the possibility of optimizing sensor arrays byappropriate selections of microelectrode parameters and nanostructured sensing films.
A Microsystem Based on Porous Silicon-Glass Anodic Bonding for Gas and Liquid Optical Sensing
Authors: De Stefano Luca , Malecki Krzysztof , Della Corte Francesco  G. , Moretti Luigi , Rea Ilaria , Rotiroti Lucia , Rendina Ivo
Published: October 2008

We have recently presented an integrated silicon-glass opto-chemical sensor forlab-on-chip applications, based on porous silicon and anodic bonding technologies. In thiswork, we have optically characterized the sensor response on exposure to vapors of severalorganic compounds by means of reflectivity measurements. The interaction between theporous silicon, which acts as transducer layer, and the organic vapors fluxed into the glasssealed microchamber, is preserved by the fabrication process, resulting in optical pathincrease, due to the capillary condensation of the vapors into the pores. Using theBruggemann theory, we have calculated the filled pores volume for each substance. Thesensor dynamic has been described by time-resolved measurements: due to the analysischamber miniaturization, the response time is only of 2 s. All these results have beencompared with data acquired on the same PSi structure before the anodic bonding process.
Near-UV Transmittance of Basalt Dust as an Analog of the Martian Regolith: Implications for Sensor Calibration and Astrobiology
Authors: Caro G.  M. Muñoz , Mateo-Martí E. , Martínez-Frías J.
Published: October 2008

The Martian regolith is exposed to solar irradiation in the near-UV (200-390 nm).Basalt is one of the main components of the dust on Mars surface. The near-UV irradiationof basalt dust on Mars is simulated experimentally in order to determine the transmittance asa function of the mass and thickness of the dust. This data can serve to quantify theabsorption of dust deposited on sensors aiming to measure the UV intensity on Marssurface. The minimum thickness of the dust that corresponds to near-zero-transmittance inthe near-UV is measured. Hypothetical Martian microorganisms living on the dusty regolithat deeper layers would be preserved from the damaging solar UV irradiation.
Improving the Response of a Load Cell by Using Optimal Filtering
Authors: Hernandez Wilmar
Published: October 2008

Load cells are transducers used to measure force or weight. Despite the fact thatthere is a wide variety of load cells, most of these transducers that are used in the weighingindustry are based on strain gauges. In this paper, an s-beam load cell based on strain gaugeswas suitably assembled to the mechanical structure of several seats of a bus underperformance tests and used to measure the resistance of their mechanical structure to tensionforces applied horizontally to the seats being tested. The load cell was buried in a broad-band noise background where the unwanted information and the relevant signal sometimesshare a very similar frequency spectrum and its performance was improved by using arecursive least-squares (RLS) lattice algorithm. The experimental results are satisfactoryand a significant improvement in the signal-to-noise ratio at the system output of 27 dB wasachieved, which is a good performance factor for judging the quality of the system.
A Miniaturized Magnetic Induction Sensor Using Geomagnetism for Turn Count of Small-Caliber Ammunition
Authors: Yoon Sang-Hee , Lee Seok-Woo , Lee Young-Ho , Oh Jong-Soo
Published: October 2008

This paper presents a miniaturized magnetic induction sensor (MMIS), wheregeomagnetism and high rpm rotation of ammunition are used to detect the turn number ofthe ammunition for applications to small-caliber turn-counting fuzes. The MMIS, composedof cores and a coil, has a robust structure without moving parts to increase the shocksurvivability in a gunfire environment of ~30,000 g’s. The MMIS is designed and fabricatedon the basis of the simulation results of an electromagnetic analysis tool, Maxwell® 3D. Inthe experimental study, static MMIS test using a solenoid-coil apparatus and dynamicMMIS test (firing test) have been made. The present MMIS has shown that an inductionvoltage of 6.5 mVp-p is generated at a magnetic flux density of 0.05 mT and a rotationalvelocity of 30,000 rpm. From the measured signal, MMIS has shown a signal-to-noise ratioof 44.0 dB, a nonlinearity of 0.59%, a frequency-normalized sensitivity of 0.256±0.010V/T·Hz and a drift of 0.27% in the temperature range of -30~ 43°C. Firing test has shownthat the MMIS can be used as a turn-counting sensor for small-caliber ammunition,verifying the shock survivability of the MMIS in a high-g environment.
Mathematical Modeling of Plate−gap Biosensors with an Outer Porous Membrane
Authors: Baronas Romas , Ivanauskas Feliksas , Kaunietis Irmantas , Laurinavicius Valdas
Published: October 2008

A plate−gap model of a porous enzyme doped electrode covered by a porousinert membrane has been proposed and analyzed. The two−dimensional−in−spacemathematical model of the plate−gap biosensors is based on the reaction−diffusionequations containing a nonlinear term related to the Michaelis−Menten kinetics. Usingnumerical simulation of the biosensor action, the influence of the geometry of the outermembrane on the biosensor response was investigated at wide range of analyteconcentrations as well as of the reaction rates. The numerical simulation was carried outusing finite−difference technique. The behavior of the plate−gap biosensors was comparedwith that of a flat electrode deposited with a layer of enzyme and covered with the sameouter membrane.
A Comparison of Frequency Pullability in Oscillators Using a Single AT-Cut Quartz Crystal and Those Using Two Single AT- Cut Crystals Connected in Parallel with a Series Load Capacitance or Series Load Inductance
Authors: Matko Vojko
Published: October 2008

This paper presents a comparison of frequency pullability in oscillators using asingle AT-cut crystal and those using two single AT-cut crystals connected in paralleloperated with a series load capacitance or series load inductance at fundamental frequenciesof 4, 10 and 19 MHz. Pullability describes how the operating frequency may be changed byvarying the load capacitance. The paper also gives impedance circuits for both single- anddual-crystal units. The experiment results show that the new approach using two singlequartz crystals connected in parallel increases the frequency pulling range by 30-200% pending on the type of oscillator. Also given is the crystal frequency stability at thesethree frequencies.
Aspartate Aminotransferase (AST/GOT) and Alanine Aminotransferase (ALT/GPT) Detection Techniques
Authors: Huang Xing-Jiu , Choi Yang-Kyu , Im Hyung-Soon , Yarimaga Oktay , Yoon Euisik , Kim Hak-Sung
Published: October 2008

The levels of aspartate aminotransferase (AST/GOT) and alanineaminotransferase (ALT/GPT) in serum can help people diagnose body tissues especially theheart and the liver are injured or not. This article provides a comprehensive review ofresearch activities that concentrate on AST/GOT and ALT/GPT detection techniques due totheir clinical importance. The detection techniques include colorimetric, spectrophotometric,chemiluminescence, chromatography, fluorescence and UV absorbance, radiochemical, andelectrochemical techniques. We devote the most attention on experimental principle. Insome methods a few representative devices and important conclusions are presented.
Solid State pH Sensor Based on Light Emitting Diodes (LED) As Detector Platform
Authors: Lau King Tong , Shepherd R. , Diamond Danny , Diamond Dermot
Published: October 2008

A low-power, high sensitivity, very low-cost light emitting diode (LED)-baseddevice developed for low-cost sensor networks was modified with bromocresol greenmembrane to work as a solid-state pH sensor. In this approach, a reverse-biased LEDfunctioning as a photodiode is coupled with a second LED configured in conventionalemission mode. A simple timer circuit measures how long (in microsecond) it takes for thephotocurrent generated on the detector LED to discharge its capacitance from logic 1 ( 5 V)to logic 0 ( 1.7 V). The entire instrument provides an inherently digital output of lightintensity measurements for a few cents. A light dependent resistor (LDR) modified withsimilar sensor membrane was also used as a comparison method. Both the LED sensor andthe LDR sensor responded to various pH buffer solutions in a similar way to obtainsigmoidal curves expected of the dye. The pKa value obtained for the sensors was found toagree with the literature value.
Special Issue of Photonic Sensors for Chemical, Biological, and Physical Parameter Detection
Authors: Pickrell Gary
Published: October 2008

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Aptamer Based Microsphere Biosensor for Thrombin Detection
Authors: Zhu Hongying , Suter Jonathan D. , White Ian M. , Fan Xudong
Published: October 2008

We have developed an optical microsphere resonator biosensor using aptamer asreceptor for the measurement of the important biomolecule thrombin. The sphere surface ismodified with anti-thrombin aptamer, which has excellent binding affinity and selectivityfor thrombin. Binding of the thrombin at the sphere surface is monitored by the spectralposition of the microsphere’s whispering gallery mode resonances. A detection limit on theorder of 1 NIH Unit/mL is demonstrated. Control experiments with non-aptameroligonucleotide and BSA are also carried out to confirm the specific binding betweenaptamer and thrombin. We expect that this demonstration will lead to the development ofhighly sensitive biomarker sensors based on aptamer with lower cost and higher throughputthan current technology.
Fiber-Optic Biosensor Employing Alexa-Fluor Conjugated Antibody for Detection of Escherichia coli O157:H7 from Ground Beef in Four Hours
Authors: Geng Tao , Uknalis Joe , Tu Su-I , Bhunia Arun K.
Published: October 2008

Fiber optic biosensor has a great potential to meet the need for rapid, sensitive,and real-time microbial detection systems. We developed an antibody-based fiber-opticbiosensor to rapidly detect low levels of Escherichia coli O157:H7 cells in ground beef. Theprinciple of the sensor is a sandwich immunoassay using an antibody which is specific forE. coli O157:H7. A polyclonal antibody was first immobilized on polystyrene fiberwaveguides through a biotin-streptavidin reaction that served as a capture antibody. AnAlexa Fluor 647 dye-labeled antibody to E. coli O157:H7 was used to detect cells andgenerate a specific fluorescent signal, which was acquired by launching a 635 nm laser-lightfrom an Analyte-2000. Fluorescent molecules within several hundred nanometers of thefiber were excited by an evanescent wave, and a portion of the emission light fromfluorescent dye transmitted by the fiber and collected by a photodetector at wavelengths of670 to 710 nm quantitatively. This immunosensor was specific for E. coli O157:H7compared with multiple other foodborne bacteria. In addition, the biosensor was able todetect as low as 103 CFU/ml pure cultured E. coli O157:H7 cells grown in culture broth.Artificially inoculated E. coli O157:H7 at concentration of 1 CFU/ml in ground beef couldbe detected by this method after only 4 hours of enrichment.
Antibody Immobilization on Waveguides Using aFlow–Through System Shows Improved Listeria monocytogenesDetection in an Automated Fiber Optic Biosensor: RAPTORTM
Authors: Nanduri Viswaprakash , Kim Giyoung , Morgan Mark T. , Ess Daniel , Hahm Byoung-Kwon , Kothapalli Aparna , Valadez Angela , Geng Tao , Bhunia Arun K.
Published: October 2008

Recent outbreaks of food borne illnesses continue to support the need for rapidand sensitive methods for detection of foodborne pathogens. A method for detecting Listeriamonocytogenes in food samples was developed using an automated fiber-optic-basedimmunosensor, RAPTORTM. Detection of L. monocytogenes in phosphate buffered saline(PBS) was performed to evaluate both static and flow through antibody immobilizationmethods for capture antibodies in a sandwich assay. Subsequent detection in frankfurtersamples was conducted using a flow through immobilization system. A two stage blockingusing biotinylated bovine serum albumin (b-BSA) and BSA was effectively employed toreduce the non-specific binding. The sandwich assay using static or flow through mode ofantibody immobilization could detect 1
Single-crystal Sapphire Based Optical Polarimetric Sensor for High Temperature Measurement
Authors: Zhang Yibing , Pickrell Gary R. , Qi Bing , Safaai-Jazi Ahmad , Wang Anbo
Published: October 2008

Optical sensors have been investigated and widely deployed in industrial andscientific measurement and control processes, mainly due to their accuracy, high sensitivityand immunity to electromagnetic interference and other unique characteristics. They areespecially suited for harsh environments applications, where no commercial electricalsensors are available for long-term stable operations. This paper reports a novel contactoptical high temperature sensor targeting at harsh environments. Utilizing birefringentsingle crystal sapphire as the sensing element and white light interferometric signalprocessing techniques, an optical birefringence based temperature sensor was developed.With a simple mechanically structured sensing probe, and an optical spectrum-codedinterferometric signal processor, it has been tested to measure temperature up to 1600 °Cwith high accuracy, high resolution, and long-term measurement stability.
Nanoporous Zeolite Thin Film-Based Fiber Intrinsic Fabry-Perot Interferometric Sensor for Detection of Dissolved Organics in Water
Authors: Liu Ning , Hui Juan , Sun Cunqiang , Dong Junhang , Zhang Luzheng , Xiao Hai
Published: October 2008

A fiber optic intrinsic Fabry-Perot interferometric (IFPI) chemical sensor wasdeveloped by fine-polishing a thin layer of polycrystalline nanoporous MFI zeolitesynthesized on the cleaved endface of a single mode fiber. The sensor operated bymonitoring the optical thickness changes of the zeolite thin film caused by the adsorption oforganic molecules into the zeolite channels. The optical thickness of the zeolite thin filmwas measured by white light interferometry. Using methanol, 2-propanol, and toluene as themodel chemicals, it was demonstrated that the zeolite IPFI sensor could detect dissolvedorganics in water with high sensitivity.
Nucleoside Sensing
Authors: Fokkens Michael , Klärner Frank-Gerrit , Schrader Thomas
Published: October 2008

A rigid molecular clip comprising bisphosphonate binding sites and aromaticsidewalls forming an electron-rich cavity is able to distinguish between nucleosides andnucleotides in aqueous solution. Neutral nucleosides as well as antibiotics derived thereofare drawn into the unpolar interior of the cleft and lead to substantial upfield-shifts in the 1HNMR spectrum. Nucleoside drugs can therefore be detected with high selectivity in thepresence of their phosphorylated pendants or nucleic acids.