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The paper considers the advantages and disadvantages of existing methods for temperature compensation of data from fiber-optic sensors based on fiber Bragg gratings as part of an embedded system for simultaneous testing of deformation and temperature of polymer composite materials. It is shown that when external temperature testing is impossible, it is most expedient to implement the method of two optical fibers with different sensitivity to at least one of these parameters due to different dopants. Technological issues related to the formation of a spatial topology and the provision of an effective survey of the embedded optical system for monitoring polymer composite materials by the two-fiber method are considered. The results of theoretical research of a linear model of temperature compensation, a model that takes into account the influence of cross sensitivity, as well as a quadratic model of temperature compensation of optical testing data are presented. It has been established that the linear model is the simplest, however, when using it, one should take into account the error associated with the inaccuracy of the approximation of optical inspection data by a linear function. At the same time, it is shown that in order to improve the quality and reliability of the results of optical testing, it is advisable to use a quadratic model of temperature compensation, which provides an error level comparable to the error of the fiber-optic sensor survey device. The results obtained can be used to develop methods for the simultaneous testing of samples, as well as monolithic and three-layer structures from structural layered polymer composite materials with limiting molding conditions (temperature less than 180°C, specific pressure lower than 0.7 MPa), as in the process of bench and other tests, and, in the future, in real operating conditions. [ABSTRACT FROM AUTHOR]

Dissolved organic material (DOM) has posed adverse impacts on the detection of water quality between different water pollutants. Once the total amount of DOM reaches a critical level, the explosive growth of algae can be induced by eutrophication in the water, leading to a more complicated composition. There is a more serious interference in the detection, as the DOM aggravated during this time. The previous research also shows that the effect of DOM is closely related to the total amount, and the components. It is a high demand to accurately measure the DOM components for effective water quality monitoring. Particularly, the DOM component measurement is highly required to effectively implement, due to the complex organic structure. For this reason, it is difficult for a single sensor to complete the complicated test of the total amount and components of DOM in water. In this study, the fiber sensing array was proposed to detect the DOM components using the non-specific selectivity of the fiber SPR sensor. The cross-sensitivity analysis was carried out to obtain the different SPR sensing arrays using the fiber SPR sensor. A field test was been realized by the SPR sensing array in large-scale water bodies. Particle Swarm Optimization (PSO) was selected to optimize the artificial neural network (ANN). As such, effective predictions were obtained for the five DOM components and their concentrations in four kinds of measured water. The SPR sensors were then prepared with different optimal refractive indices using multimode fiber and gold film with seven thicknesses of 55-85 nm. The optimal refractive index of each sensor was effectively distributed in the range of 1.33 to 1.43, according to the design requirements. Correspondingly, each sensor presented excellent sensitivity and linearity in the best measurement interval. The sensitive crossing-response was achieved in the measurement interval corresponding to other sensors through the wavelength, spectrum width, and light intensity. In terms of the classifier and intelligent algorithm, the global search PSO was used to train the BP-ANN, in order to avoid the local search easy to fall into the local extremum. After that, the DOM water sample was prepared to determine the DOM components in the water body. The SPR effect was realized to measure the refractive index using a sensing array. The artificial intelligence network BP-ANN was trained by the PSO. Three classifiers were then constructed, including the PSO-BP (wavelength), PSO-BP (spectral width), and PSO-BP (light intensity). The comprehensive training was verified by the resonance wavelength, spectral width and light intensity of the SPR effect in the tested water. Therefore, five DOM components were tested, including the tyrosine proteins, tryptophan proteins, fulvic acid, soluble microbial metabolites, and humic acids of Outer Canal (A), Hongze Lake (B), Park Landscape Lake (C) and Campus Landscape Lake (D). The highest recognition rate was up to 85% from the samples of P2.n in Hongze Lake (B), indicating the excellent prediction of DOM components. Anyway, the PSO-BP multi-classifiers can be expected to mine the cross-sensitivity information by the SPR sensor. The finding can provide a new idea for the application of fiber SPR sensors and multi-classifiers using cross-sensitivity analysis. [ABSTRACT FROM AUTHOR]

This work designed a dual-wavelength 2D fiber Bragg grating (FBG) engraved on the single-mode fiber to measure the temperature and strain. The FBG is composed of two sub-gratings that are not overlapped spatially at the same location of the fiber core. Experiments showed that the temperature and strain sensitivities of this grating were separately measured to be 10.64 p.m./°C and 0.882,731 p.m./μɛ at the central wavelength of 1,548 nm, and 10.74 p.m./°C and 0.916,080 p.m./μɛ at the central wavelength of 1,550 nm. These coefficients constitute a coefficient matrix that can solve the problem of cross sensitivity between temperature and strain, which has been verified by varying central wavelengths caused by the synchronous change of temperature and strain.

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A temperature-compensated MZI-based optical sensor using few-mode concentric multilayer-core fiber (CMCF) was designed, and surrounding refractive index (SRI) sensing via interference spectra was successfully proposed and experimentally demonstrated. This sensor with sandwich structure generated lots of resonance dips in the interference spectra, which had differentiated sensitivities to SRI and temperature. The homemade CMCF only supported few mode groups, and variability of the resonance drift could be influenced by different mode excitation and sensitivity. For the two selected dips of this proposed sensor, the SRI sensitivities experimentally achieved were −76.88 and −50.51 nm per refractive index unit (RIU), and the temperature ones were 80.2 and 50.1 pm/°C, respectively. The experimental mechanism and results have been analyzed in brief. The standard matrix inversion method could be used for simultaneous two parameter determination. Therefore, the SRI detection could show good accuracy and sensitivity by temperature compensation.

Use of a detailed parallel theoretical model has allowed the design of a high figure of merit and low cross sensitivity accelerometer based on fiber Bragg grating (FBG), and the good response characteristics have been demonstrated experimentally. The relationship between the sensitivity and resonant frequency is downplayed, the mechanism of expanding the frequency band and maintaining higher sensitivity has been analyzed. A FBG accelerometer with a good performance of higher main-axis sensitivity and lower cross sensitivity has been presented. The experimental results obtained indicate that the FBG accelerometer has a broad frequency range from 1 to 60Hz, the corresponding sensitivity range from 754.3 to 763.2pm/G, while the fluctuation is less than 3dB. The resonant frequency is 103Hz, and the corresponding cross sensitivity is less than −24.76dB (< 5%). The figure of merit is 78.61nm $\cdot $ Hz/G, it shows that the sensor has better comprehensive characteristics. An accelerometer with this performance thus has the potential for application in low frequency oil and gas seismic exploration. [ABSTRACT FROM AUTHOR]

Low-cost, accurate monitoring of macronutrient ions in soils, plants, and water is highly desired to improve fertilizer management for maximum profitability and minimum negative environmental impacts. Traditional ion-selective electrodes (ISEs) suffer from interference from non-target ions. This paper reports the integration of artificial neural networks (ANNs) and a miniature sensor containing an array of three ISE-based sensing elements to improve accuracy of the sensor in detecting and quantifying target nitrate (${\mathrm {NO}}_{3}^{-}$), phosphate (H2 ${\mathrm {PO}}_{4}^{-}$), and potassium (K+) ions in the environment. The sensor outputs of ${\text{NO}}_{3}^{-}$ , H2 ${\text{PO}}_{4}^{-}$ , and K+ ion concentrations are used to train and optimize ANNs. The optimized neural networks are applied to classify and estimate concentrations of the target ions in the presence of interfering ions. The ANN-assisted array of sensing elements reduces cross-sensitivity between these elements. The present sensor is validated with measurements of ${\text{NO}}_{3}^{-}$ , $\text{H}_{2} {PO}_{4}^{-}$ , and K+ ions in soil solution, plant sap, and tile drainage water from crop fields. [ABSTRACT FROM AUTHOR]

We have designed a Fabry–Pérot interferometric fiber sensor based on the principal component analysis (PCA) assisted orbital angular momentum (OAM) interrogation for simultaneous measurement of magnetic field intensity and temperature. A hollow core fiber sandwiched between two segments of single mode fiber serving as the sensing probe, is introduced to the Gaussian interference arm. Encapsulated with magnetic fluid, the intensity and phase of Gaussian beam are highly sensitive to the variations of magnetic field and temperature, exerting a modulation on the intensity and rotation angle of OAM interferograms. A dual-parameter sensing matrix to discrimination the cross-sensitivity could be established via the PCA-assisted OAM interrogation. The minimum sensing resolutions of magnetic field and temperature are calculated as 0.06 G and 0.0079 °C, respectively. • A Fabry–Pérot interferometric sensing system using principal-component analysis-based OAM interrogation is designed. • A dual-parameter sensing matrix is established to resolve the cross-sensitivities between magnetic field and temperature. • The minimum sensing resolutions of magnetic field and temperature are calculated as 0.06 G and 0.0079 ℃, respectively. [ABSTRACT FROM AUTHOR]

Hybrid materials based on perfluorinated sulfonic acid Nafion-type membranes and poly-3,4-ethylenedioxythiophene (PEDOT) with a gradient distribution of the latter along the film length were synthesized by in situ oxidative polymerization. The initial monomer concentration (0.01 and 0.002 M) and the concentration ratio of the monomer to the oxidant (1/1.25 and 1/2.5) were varied. We studied the effect of the equilibrium and transport properties of the obtained materials on the characteristics of cross-sensitive DP-sensors (analytical signal is the Donnan potential) in aqueous solutions of procaine, lidocaine, and bupivacaine hydrochlorides, including those containing sodium chloride, in a concentration range from 1.0 × 10–4 to 1.0 × 10–2 M and pH from 2 to 6. The relative error in determining the active substance in the Novokain preparation using a DP-sensor based on the Nafion/PEDOT membrane (0.002 M, 1/2.5) was 0.4%. An array of DP-sensors based on Nafion and Nafion/PEDOT (0.002 M, 1/1.25) membranes was used to determine bupivacaine hydrochloride and sodium chloride in the Markain® Spinal preparation with an error of 11 and 6%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, an in-fiber Mach–Zehnder interferometer (MZI) is developed for refractive index (RI) sensing through core-offset splicing. In MZI, two ends of a section erbium-doped fiber are asymmetrically spliced with two pieces of single-mode fiber in order to get large contrast ratio of fringes. The comprehensive experimental measurements are then performed in terms of temperature and ambient RI. Owing to high sensitive consistency in temperature, a novel common difference compensation (CDC) method is introduced to achieve the self-elimination of cross-sensitivity. Thus the measurement error ( ∼ 1.2%) can be deleted by CDC and the corrected sensitivity (-74.22nm/RIU) is obtained without the crosstalk from temperature In addition, high working stabilities are demonstrated in the fabricated RI sensor in terms of wavelength ( ± 0.02 nm) and intensity ( ± 0.03 dB). [ABSTRACT FROM AUTHOR]

SnO 2 coatings were deposited on alumina substrates using an atmospheric plasma spray. The coating morphology and phase structure were characterized by scanning electron microscopy and X-ray diffraction. Two different coatings were fabricated using nitrogen as a plasma forming gas with and without hydrogen. The arc current was kept fixed at 400 A during deposition. The ethanol sensing capability of these two coatings was studied using a cost effective homemade quasi-static sensing chamber. The sensing measurement was performed in the temperature range of 175–300 °C. The coating deposited at 400 A without hydrogen showed higher response in the presence of ethanol. It was tested further in the presence of acetone and isopropanol to check the cross-sensitivity. The concentration dependent response characteristics of the same coating were investigated in the range of 25–300 ppm. This coating exhibited excellent repeatability characteristics in the presence of ethanol at 300 °C.Coating showed excellent durability in the presence of ethanol. The effect of relative humidity on the sensor response was also investigated. The temperature dependent response was modeled using a gas diffusion theory to better understand the sensing characteristics. From the simulated temperature dependence of sensor responses we have estimated activation energy for transduction and first order kinetics together with the sensitivity of these sensors. We have argued that differences of these activation energies could be a basis to address the cross-sensitivity issues toward acetone and isopropanol sensing. To the best of authors' knowledge, this is the first report exploring the sensing capability of atmospheric plasma sprayed SnO 2 coatings. [ABSTRACT FROM AUTHOR]

The effect of heat treatment at varying relative humidity and mechanical deformation on the properties of Nafion perfluorosulfonic cation-exchange membranes and Nafion-based hybrid materials containing hydrated zirconia nanoparticles has been studied. It has been shown that the treatment of the materials makes it possible to change their water uptake, ionic conductivity, and diffusion permeability over wide ranges. Variations in the water uptake and intrapore space volume of the membranes provided by their treatment and modification have led to a decrease in the sensitivity of DP-sensors (the analytical signal is the Donnan potential) to interfering hydroxonium cations in arginine and histidine solutions in 1.5−5 times. The material samples providing a high accuracy of determination of amino acid ions in a concentration range from 1.0 × 10–4 to 1.0 × 10–1 mol/L at pH < 7 have been selected. [ABSTRACT FROM AUTHOR]

The influence of incorporation of the dopants with proton-acceptor properties into perfluorosulfonic acid cation exchange membranes (MF-4SC and Nafion), and their treatment conditions on the characteristics of Donnan potential (DP)-sensors (analytical signal is the Donnan potential) in the aqueous solutions containing asparaginate and potassium ions in a wide pH range was investigated. A silica, surface modified by 3-aminopropyl and 3-(2-imidazolin-1-yl)-propyl groups, was used as the dopant. The membranes were subjected to mechanical deformation and thermal treatment at various relative humidities. The relationship between water uptake and diffusion permeability of membranes subjected to modification and treatment and the cross sensitivity of DP-sensors based on them to counter and co-ions was studied. The multisensory systems for the simultaneous determination of asparaginate and potassium ions in a concentration range from 1.0 × 10−4 to 1.0 × 10−2 M and pH range from 4 to 8 were developed. An array of cross-sensitive DP-sensors based on MF-4SC membranes containing 3 wt.% SiO2 modified by 10 mol.% 3-aminopropyl and 3-(2-imidazolin-1-yl)-propyl was used for the potassium asparaginate hemihydrate and magnesium asparaginate pentahydrate determination in Panangin® (with an error of 2 and 4%, respectively).

WS2 exfoliated by a combined ball milling and sonication technique to produce few-layer WS2 is characterized and assembled as chemo-resistive NO2, H2 and humidity sensors. Microstructural analyses reveal flakes with average dimensions of 110 nm, “aspect ratio” of lateral dimension to the thickness of 27. Due to spontaneous oxidation of exfoliated WS2 to amorphous WO3, films have been pre-annealed at 180 °C to stabilize WO3 content at ≈58%, as determined by X-ray Photoelectron Spectroscopy (XPS), Raman and grazing incidence X-ray Diffraction (XRD) techniques. Microstructural analysis repeated after one-year conditioning highlighted that amorphous WO3 concentration is stable, attesting the validity of the pre-annealing procedure. WS2 films were NO2, H2 and humidity tested at 150 °C operating Temperature (OT), exhibiting experimental detection limits of 200 ppb and 5 ppm to NO2 and H2 in dry air, respectively. Long-term stability of the electrical response recorded over one year of sustained conditions at 150 °C OT and different gases demonstrated good reproducibility of the electrical signal. The role played by WO3 and WS2 upon gas response has been addressed and a likely reaction gas-mechanism presented. Controlling the microstructure and surface oxidation of exfoliated Transition Metal Dichalcogenides (TMDs) represents a stepping-stone to assess the reproducibility and long-term response of TMDs monolayers in gas sensing applications.

A fast and reliable determination of the ethanol concentration is essential in the analysis of alcoholic beverages. However, different factors like pH value or salt concentration can influence the ethanol measurement. Furthermore, analytical figures of merit for the alcohol sensor, such as limit of detection, sensitivity and measurement uncertainty, are necessary for the application. In this paper, a detailed sensor characterization of a novel sensor based on ethanol-sensitive poly acrylamide hydrogels will be presented. The resulting swelling pressure of the hydrogel was transformed via a piezoresistive pressure sensor into a measurable output voltage. These kinds of sensors can be used over a large measuring range, up to 50 vol% ethanol and more, with a high sensitivity. In the range from pH 7.4 to 4, the pH value had no influence on the sensor signal. Higher salt concentrations can slightly influence the measurement. The detection limit amounts to 0.06–0.65 vol% ethanol. The concentration of a vodka sample was determined with a sufficient measuring uncertainty.

The results of studying characteristics of potentiometric DP-sensors (sensors with the Donnan potential as their analytical signal) are presented for alkaline solutions of a sulfur-containing amino acid with perfluorosulfonic cation exchange membranes subjected to thermal treatment and mechanical deformation at different relative humidity. Correlation between the distribution of sensitivity of DP-sensors towards cations and anions and diffusion permeability of membranes was found. A multisensor system including two DP-sensors based on membranes with optimized properties and a glass electrode for codetermination of potassium cations and amino acid anions and zwitterions in solutions at pH > 7 are developed. [ABSTRACT FROM AUTHOR]

A cataluminescence (CTL) based method for simultaneously identifying and determining formaldehyde (HCHO), benzene (C 6 H 6 ) and ammonia (NH 3 ) in air was proposed. CTL is emitted from the surface of nano-sized Ti 2 YAl 3 O 10 contained in a CTL reactor. Three analysis wavelengths of 350 nm, 440 nm and 560 nm were selected. The surface temperature of sensing materials was 340 °C. The flow rate of air carrier was 140 mL/min. The limits of detection were 0.07 mg/m 3 for HCHO, 0.10 mg/m 3 for C 6 H 6 and 0.15 mg/m 3 for NH 3 . The linear ranges of CTL intensity versus analyte concentration were 0.2–66.4 mg/m 3 for HCHO, 0.5–71.5 mg/m 3 for C 6 H 6 and 0.5–63.8 mg/m 3 for NH 3 . The recoveries of 10 testing standard samples was 97.5%–103.1% for HCHO and 96.8%–102.8% for C 6 H 6 and 98.1%–103.7% for NH 3 . Common coexistence matters, such as acetaldehyde, toluene, ethyl benzene, methylamine, ethylamine, methanol, ethanol, sulfur dioxide, hydrogen sulfide and carbon dioxide, did not disturb the determination. The relative deviation of CTL intensities was less than 3% for continuous 200 h detection, which demonstrated the longevity and steady performance of nano- Ti 2 YAl 3 O 10 to HCHO, C 6 H 6 and NH 3 . [ABSTRACT FROM AUTHOR]

The authors describe a cataluminescence (CTL) based sensing method via signals generated at the surface of InLaTiO nanoparticles for simultaneous determination of trimethylamine, formaldehyde and benzene in air. The analytical wavelengths are 340 nm, 440 nm and 600 nm, and the best surface temperature of the catalytic material is 275 °C. The limits of detection of this method are 0.3 mg⋅m for trimethylamine, 0.07 mg⋅m for formaldehyde, and 0.2 mg⋅m for benzene. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg⋅m for trimethylamine, from 0.2 to 72.5 mg⋅m for formaldehyde, and from 0.5 to 77.5 mg⋅m for benzene. The recoveries after testing 10 standard samples ranged from 98.1% to 102.6% for trimethylamine, from 98.1% to 102.6% for formaldehyde, and from 97.7% to 103.8% for benzene. Gaseous ammonia, acetaldehyde, toluene, ethylbenzene, ethanol, sulfur dioxide and carbon dioxide do not interfere. The relative deviation of the CTL signals after 200 h of continuous detection of trimethylamine, formaldehyde and benzene is <3%. [ABSTRACT FROM AUTHOR]

We have investigated the sensing characteristics of ethanol, methanol, acetone, and 2-propanol using wet chemical synthesized copper oxide (CuO) thin films deposited on fused quartz substrates. As compared to the volatile organic component (VOC) sensing characteristics of CuO films reported in recent literatures, our thin film sensors offer relatively higher response (%), lower optimized temperature (corresponds to highest response%), better stability, and faster response time. In order to address the cross-sensitivity towards these VOC sensing we had performed fast Fourier transformation (FFT) analyses of the resistance transients. The resultant data matrices extracted from these FFT analyses were used as input parameter in a linear unsupervised principal component analysis (PCA) pattern recognition technique. We have demonstrated that FFT combined with PCA is an excellent tool for differentiating these reducing gases. [ABSTRACT FROM AUTHOR]

In this paper we report the influence of the absolute surface area (ASA) and aspect ratio (L/D) of hydrothermally grown ZnO nanorods (NRs) on the NO 2 and H 2 gases relative responses (RRs) in the 20 ppb − 1 ppm and 50 ppm–1000 ppm concentrations range. We used films of NRs characterized by different geometrical features, such as diameter, length, L/D and ASA, obtained using different growth times, but all showing a well-defined hexagonal shape and an alignment perpendicular to the substrate. Values of L/D up to 129 and NRs lengths up to 14 μm have been obtained; one of the highest reported for quasi-one-dimensional ZnO nanostructures obtained through solution-based one-pot syntheses. Electrical tests at 150 °C (NO 2 ) and 200 °C (H 2 ) carried out using films of NRs presenting different L/D evidenced a direct relationship between the increase of the ASA and L/D and gas RRs. The influence of geometrical and chemical characteristics, such as diameter, size and surface-defects concentration is also discussed in light of the existing literature. Cross sensitivity, investigated measuring the H 2 (target) response in the presence of NO 2 (interfering) gases as well as dynamic and cumulative NO 2 gas reproducibility test are also presented. Beside the considerable interference played by NO 2 to the H 2 response, our long NRs demonstrate an excellent reproducibility of the electrical signal and fast recovery of the base line, evidencing the absence of irreversible chemisorption or sample-surface “history-related” phenomena. [ABSTRACT FROM AUTHOR]

A highly sensitive strain sensor based on coupled two-dimensional (2D) photonic crystal waveguides consisting of dielectric rods array immersed in air is designed. The effective side-coupling between directional coupled waveguides and surrounding defect cavities gives flexibility in the choice of the sensing monitoring band. The coupling process and transmission spectral properties are analyzed by the finite difference time domain (FDTD) method. The influence of strain and temperature on the transmission spectrum is investigated by monitoring the wavelength shift in the loss peaks. The dual-channel sensing method is proposed to eliminate the cross sensitivity effect between the strain and ambient temperature, and render a new category of temperature-independent strain sensing devices. [ABSTRACT FROM AUTHOR]

Cross sensitivity due to temperature variation and the presence of other contaminants in an analyte could affect the accuracy of concentration measurement made by a sensor. In this study, a miniaturized non-adiabatic interferometer fiber optic sensor (NAIFOS) is used to monitor the Remazol Black B (RBB) dye concentration in the presence of other contaminants, pH adjustment and temperature variation. The objective of this experiment is to investigate the ability and accuracy of the sensor to monitor RBB concentration under the influence of cross-sensitivity from a single spectrum, which is considered as an advantage over traditional sensing techniques. The developed sensor shows a dye concentration sensitivity of 0.0013 nm/ppm between 0 and 800 ppm when conducted room temperature without the presence of other contaminants. The influence of pH, suspended solids in the sample and temperature variation on the accuracy of the measurement is also examined. The results show that the sensor could still provide an accurate measurement if the pH value falls between 3.07 and 10.09 with very low concentration of suspended solids (approximately 1 mg/L). In addition, a corrective measure for temperature bias is carried out by compensating the cross-sensitivity effect and a model for temperature compensation is established. To the best of our knowledge, this might well be the first attempt to establish temperature correction and compensation for optical fiber sensing using non-adiabatic tapered fiber sensor. In extended experiments involving many concentration levels, the results obtained are encouraging. [ABSTRACT FROM AUTHOR]

The cross sensitive sensors whose analytical signal is the Donnan potential (PD-sensors) were developed for the determination of the amino acids glycine, alanine, and leucine in acidic and alkaline solutions. Hybrid materials based on perfluorinated sulfo cation-exchange membranes Nafion and MF-4SC with incorporated zirconium dioxide and silicon dioxide nanoparticles, including those with modified surfaces containing proton-acceptor groups, were used in the PD-sensors. The sensitivity of the PD-sensors to hydronium ions, which interfere with the determination of amino acids at pH < 7, was considerably decreased due to the use of the membranes obtained by an in situ method that contained silicon dioxide nanoparticles with amine-containing groups. The greatest sensitivity of the PD-sensors to the anions of amino acids at pH > 7 and the smallest sensitivity to the cations K were observed in hybrid membranes, which combined an increased rate of anion transfer and a low moisture capacity. The use of the PD-sensors based on hybrid membranes makes it possible to determine the cations, anions, and zwitterions of amino acids over a wide range of pH with a sufficiently high accuracy. [ABSTRACT FROM AUTHOR]

A credible method based on cross sensitivity of cataluminescence (CTL) on nano-Ti 3 SnLa 2 O 11 was proposed for simultaneously determining formaldehyde and ammonia in air. The experimental conditions satisfying the algebraic sum rule of the CTL intensities of formaldehyde and ammonia were ascertained. They are two analysis wavelengths of 575 nm and 675 nm, the surface temperature of sensing materials of 350 °C and the flow rate of air carrier of 300 mL/min. The limits of detection of this method were 0.06 mg/m 3 for formaldehyde and 0.14 mg/m 3 for ammonia. The linear ranges of CTL intensity versus analyte concentration were 0.17–51.5 mg/m 3 for formaldehyde and 0.31–59.6 mg/m 3 for ammonia. The recoveries of 10 testing standard samples by this method were 97.3–102.7% for formaldehyde and 97.6–102.4% for ammonia. Common coexistence matters, such as acetaldehyde, methylamine, benzene, toluene, ethylbenzene, ethanol, sulfur dioxide and carbon dioxide, did not disturb the determination. The relative deviation (RD) of CTL signals of continuous 150 h detection for gaseous mixture containing formaldehyde and ammonia was less than 3%, which demonstrated the longevity and steady performance of nano-Ti 3 SnLa 2 O 11 to formaldehyde and ammonia. [ABSTRACT FROM AUTHOR]

In order to set integrated procedures involving geotechnical and structural aspects finalized to buildings diagnostics, uncertainty aspects are discussed concerning three-axis accelerometers and inclinometers for a distributed sensor network. This network allows to operate in a selective manner, preferring the most critical situations. To this aim, the main aspects affecting the measurement uncertainty of sensors to be used for building diagnostic should be known. As the firstly step of the uncertainty evaluation procedure, we focused on the calibration of sensors used for the task. The requirement of low cost and complexity of sensors and test benches was considered. Experimental results show that satisfactory calibration accuracy could be achieved, also for the low frequency range, 0–10 Hz. Systematic errors are minimized and main parameters affecting uncertainty are identified, such as: the motion positioning of the accelerometer with respect to the vertical axis, the imposed motion law, the parameter used as the reference and, finally, the real radial positioning of the sensor. Requirements to be satisfied by the sensor are also analysed. [ABSTRACT FROM AUTHOR]

A multi-sensor system is a chemical sensor system which quantitatively andqualitatively records gases with a combination of cross-sensitive gas sensor arrays andpattern recognition software. This paper addresses the issue of data analysis foridentification of gases in a gas sensor array. We introduce a software tool for gas sensorarray configuration and simulation. It concerns thereby about a modular software packagefor the acquisition of data of different sensors. A signal evaluation algorithm referred to asmatrix method was used specifically for the software tool. This matrix method computes thegas concentrations from the signals of a sensor array. The software tool was used for thesimulation of an array of five sensors to determine gas concentration of CH4, NH3, H2, COand C2H5OH. The results of the present simulated sensor array indicate that the softwaretool is capable of the following: (a) identify a gas independently of its concentration; (b)estimate the concentration of the gas, even if the system was not previously exposed to thisconcentration; (c) tell when a gas concentration exceeds a certain value. A gas sensor database was build for the configuration of the software. With the data base one can create,generate and manage scenarios and source files for the simulation. With the gas sensor database and the simulation software an on-line Web-based version was developed, with whichthe user can configure and simulate sensor arrays on-line.

ABSTRACT An all-fiber temperature sensor based on two peanut-shape structures modal interferometer is demonstrated. The results show that a high temperature sensitivity of 63.7 pm/°C is acquired for the 30 mm sensor, and the strain sensitivity is as low as −0.86 pm/με. The cross sensitivity is only 0.013°C/με, which is suitable for temperature sensing. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2841-2844, 2015 [ABSTRACT FROM AUTHOR]

Cross sensitivity of potentiometric PD-sensors (sensors whose signal is Donnan potential) based on MF-4SC and Nafion cation-exchange membranes containing hydrated ZrO nanoparticles to amino acid (glycine, alanine, and leucine) ions in alkaline solutions has been investigated. By varying ZrO concentrations, it is possible to select pairs of PD-sensors that have a sufficiently high sensitivity to the amino acid anions and K cations in Gly + KOH, β-Ala + KOH, and Leu + KOH solutions, as well as the lowest correlation between responses of sensors. The pairs of PD-sensors were used for simultaneous determination of amino acid anions and K cations in alkaline solutions. [ABSTRACT FROM AUTHOR]

In this paper, we report an integrated single-chip surface acoustic wave sensor with the capability of measuring magnetic field, temperature, and humidity. The sensor is fabricated using a thermally sensitive LiNbO3 substrate, a humidity sensitive hydrogel coating, and a magnetic field sensitive impedance load. The sensor response to individually and simultaneously changing magnetic field, temperature and humidity is characterized by connecting a network analyzer directly to the sensor. Analytical models for each measurand are derived and used to compensate noise due to cross sensitivities. The results show that all three measurands can be monitored in parallel with sensitivities of 75 ppm/°C, 0.13 dB/%R.H. (at 50%R.H.), 0.18 dB/Oe and resolutions of 0.1 °C, 0.4%R.H., 1 Oe for temperature, humidity and magnetic field, respectively. A passive wireless measurement is also conducted on a current line using, which shows the sensors capability to measure both temperature and current signals simultaneously. [ABSTRACT FROM PUBLISHER]

An attempt has been made to study theoretically electrical admittance type level measurement and its cross sensitivity with ionic concentration of liquid. The analysis has been made for single and double electrodes and found there is significant cross sensitivity which varies with the ionic concentration of the liquid. This study will help further to design and develop continuous level measurement transmitter in Boiler drum. [ABSTRACT FROM AUTHOR]

The effect of the presence of bulky organic cations in the phase of perfluorosulfonated cationexchange membranes on the sensitivity of PD-sensors to ions of vitamins (nicotinic acid, pyridoxine, and thiamin) and hydronium in aqueous solutions has been studied. Three cross-sensitive PD-sensors based on perfluorinated membranes have been used for simultaneous determination of the ions of nicotinic acid, pyridoxine, and thiamine in aqueous solutions. The relative error of determination of the vitamins does not exceed 12%; the relative standard deviation of the determination results is no more than 0.04; the detection limit and the determination limit are 4.9 × 10 and 1.6 × 10 mol/L, respectively. [ABSTRACT FROM AUTHOR]

Ideally, there is a linear relationship between the max of PDL and pressure in FBG weak pressure sensor. However, the linear relationship has been broken down because of the cross sensitivity about the circular birefringence and pressure. In this paper, the relative PDL was proposed to solve the cross sensitivity problem. For different circular birefringences, the experimental results show the same pressure sensitivity value of 2.29 dB/(N/nm). The theoretical analysis and experimental results prove that the proposed method can solve the cross-sensitivity problem in FBG weak pressure sensor. This research can provide useful information to practical application. [ABSTRACT FROM AUTHOR]