An optical microsensor array is described for the rapid analysis of silver ions at low parts per trillion levels. Because the ionophore o-xylylenebis(N,N-diisobutyldithiocarbamate) (Cu-I) was reevaluated and shown to ...
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An optical microsensor array is described for the rapid analysis of silver ions at low parts per trillion levels. Because the ionophore o-xylylenebis(N,N-diisobutyldithiocarbamate) (Cu-I) was reevaluated and shown to exhibit excellent selectivity for silver ions, ion-selective electrode (ISE) membranes were optimized and found to exhibit the lowest reported detection limit so far (3 x 10(-10) M). A corresponding Ag+-selective fluorescent optical microsensor array for the rapid sensing of trace level Ag+ was then developed. It was fabricated using plasticized PVC-based micrometer-scale fluorescent microspheres that were produced via a sonic particle casting device. They contained 156 mmol/kg Cu-I, 10 mmol/kg 9-(diethylamino)5-[4-(15-butyl-1,13-dioxo-2,14-dioxanodecyl)phenylimino]-benzo[a]phenoxazine (chromoionophore VII, EM 5418), 2.3 mmol/kg 1,1"-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (internal reference dye), and 14 mmol/kg sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate and were deposited onto the etched distal end of a 3200-mu m-diameter optical fiber bundle. The microarray was characterized by fluorescence spectroscopy in samples containing 10(-12)-10(-8) AT AgNO3 at pH 7.4, with selectivity characteristics comparable to the corresponding ISEs. The response time of the microsensor array was found to be less than 15 min for 10(-9) M AgNO3, which is drastically shorter than earlier data on optode films (8 h) and corresponding ISEs (30 min). A detection limit of 4 x 10(-11) M for Ag+ was observed, lower than any previously reported optode or silver-selective ISE. The microsensor array was applied for measurement of free silver levels in buffered pond water samples.
In this paper, an experimental study was carried out for the design of microsensor arrays dedicated to eddy current non destructive applications. A 3-microcoil 1-D array sensor was realized thanks to microtechnology. ...
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ISBN:
(纸本)9781424408412
In this paper, an experimental study was carried out for the design of microsensor arrays dedicated to eddy current non destructive applications. A 3-microcoil 1-D array sensor was realized thanks to microtechnology. Since each coil can be used as a transmitter or a receiver, five different transmission-reception strategies were considered for the inspection of a nickel based alloy target, featuring several calibrated surface notches. While the most basic strategy did not detect the smallest notch (0.1x0.1x0.1 mm(3)), the best strategy detected it with a 20 dB signal to noise ratio. The detection performances were then analyzed versus frequency and versus notch size.
This article describes the laboratory and field performance evaluation of a small prototype instrument employing art array of six polymer-coated surface acoustic wave (SAW) sensors and a thermal desorption preconcentr...
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This article describes the laboratory and field performance evaluation of a small prototype instrument employing art array of six polymer-coated surface acoustic wave (SAW) sensors and a thermal desorption preconcentration unit, for rapid analysis of perchloroethylene in breath. Laboratory calibrations were performed using breath samples spiked with perchloroethylene to prepare calibration standards spanning a concentration range of 0.1-10 ppm. A sample volume of 250 mL was preconcentrated on 40 mg of Tenax(R) GR at a flow rate of 100 mL/min, followed by a dry air purge and thermal desorption at a temperature of 200 C. The resulting pulse of vapor was passed over the sensor array at a flow rate of 20 mL/min and sensor responses were recorded rend displayed using a laptop computer: The total time per analysis was 4.5 min. SAW sensor responses were linear, and the instrument's limit of detection was estimated to be 50 ppb based on the criterion that four of the six sensors show a detectable response. Field performance was evaluated at a commercial dry-cleaning operation by comparing prototype instrument results for breath samples with those of a portable gas chromatograph (NIOSH 3704). Four breath samples were collected from a single subject over the course of the workday and avalyzed using the portable gas chromatograph (GC) and SAW instruments. An additional seven spiked breath samples were prepared and analyzed so that a broader range of perchloroethylene concentrations could be examined. Linear regression analysis showed excellent agreement between prototype instrument and portable GC breath sample results with a correlation coefficient of 0.99 and a slope of 1.04. The average error for the prototype instrument over a perchloroethylene breath concentration range of 0.9-7.2 ppm was 2.6% relative to the portable GC. These results demonstrate the field capabilities of SAW microsensor arrays for rapid analysis of organic vapors in breath.
In this paper, measurements of environmentally relevant gases (CO, CH(4) and NO(2)) with a novel single-chip digital microhotplate array are presented. The array consists of three tin-oxide-coated microhotplates with ...
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ISBN:
(纸本)0780386922
In this paper, measurements of environmentally relevant gases (CO, CH(4) and NO(2)) with a novel single-chip digital microhotplate array are presented. The array consists of three tin-oxide-coated microhotplates with integrated MOS-transistor heaters and specifically designed circuitry. The programmable digital temperature controllers enable individual regulation of the microhotplate temperatures in continuous or dynamic mode. Nanocrystalline tin-oxide thick films with different Pd dopings (undoped, 0.2 wt% and 3 wt%) were tested. Excellent dicrimination between the three gases was achieved with detection limits of less than 1 ppm for CO, 100 ppm for CH(4) (40% r. h.) and 10 ppb of NO(2) (30% / 70% r.h).
作者：
He, HQXu, GXYe, XSWang, PZhejiang Univ
Biosensor Natl Special Lab Dept Biomed Engn Biomed Engn Key LabNatl Educ Minist Hangzhou 310027 Peoples R China
A novel chemical image sensor developed for liquid component analysis is proposed in this paper;using it, pH values ranging from I to 12 and six kinds of metal ion, namely Cu2+, Fe2+, Fe3+, Ca2+, Zn2+, and Mg2+, can b...
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A novel chemical image sensor developed for liquid component analysis is proposed in this paper;using it, pH values ranging from I to 12 and six kinds of metal ion, namely Cu2+, Fe2+, Fe3+, Ca2+, Zn2+, and Mg2+, can be detected qualitatively and quantitatively. The sensor applies the principles of optical chemistry and microfabrication technology to detect the ion concentrations in the solution, and has the advantages of high sensitivity, reduced contamination, a lower sample volume required, and the capability of detecting several indices at one time. Moreover, three multivariate data analysis methods are suggested in the paper for treating the raw data acquired from the microbeads, and predicting the results. The study demonstrates that the principal component analysis is capable of classifying six kinds of cation with success. Both partial least-squares regression (PLS) and artificial neural networks (ANN) can be used to compute the pH values quantitatively;furthermore, the PLS method has the advantage of requiring fewer iteration steps than the ANN approach.
A complexing gel integrated microelectrode (CLIME) for direct measurements of free metal ion concentrations in natural waters has been developed. It is prepared by the successive deposition of microlayers of a chelati...
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A complexing gel integrated microelectrode (CLIME) for direct measurements of free metal ion concentrations in natural waters has been developed. It is prepared by the successive deposition of microlayers of a chelating resin, an antifouling agarose gel and Hg on a 100-interconnected Ir-based microelectrode array. The trace metals of interest are in a first step accumulated on the chelating resin in proportion to their free ion concentration in solution, then released in acidic solution and detected simultaneously by using square wave anodic stripping voltammetry (SWASV). The reliability of this sensor for the simultaneous measurement of copper, lead and cadmium has been studied by a series of replicate laboratory tests. The proportionality between the voltammetric peak current intensity and the free metal ion concentrations in solution has been demonstrated by using malonate as a model ligand. Finally, the CLIME sensor was applied to the Cu and Pb free concentration measurement in sea water samples and the results compared to the free metal ion concentrations measured using hollow fiber based permeation liquid membrane (HF-PLM) coupled to inductively coupled plasma mass spectrophotometer (ICP-MS). Comparable concentration values were found for both metals with both techniques allowing to validate the CLIME measurements in complex media.
This paper reports on a novel low volume delivery system for ultra-fast odour detection. A miniature microchannel delivery package has been designed and fabricated using stereolithography (STL) and interfaced to a sil...
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ISBN:
(纸本)0780386922
This paper reports on a novel low volume delivery system for ultra-fast odour detection. A miniature microchannel delivery package has been designed and fabricated using stereolithography (STL) and interfaced to a silicon microsensor array;realising a chemical microsystem. Such a system significantly reduces both the volume of analyte required and response time. In addition the combination has the added advantages of miniaturisation, e.g. lower power consumption, size and weight. Initial investigations show that the microsystem is capable of responding to both simple and complex odorants with response times of less than 100 ms. We believe that this type of chemical microsystem provides a cost-effective solution suitable for future commercialisation.
A novel method for fabricating a micro gas sensor film on an indium tin oxide (ITO) electrode patterned using micromachining technology was developed. A micromanipulation system equipped with a counter electrode (Au;c...
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A novel method for fabricating a micro gas sensor film on an indium tin oxide (ITO) electrode patterned using micromachining technology was developed. A micromanipulation system equipped with a counter electrode (Au;circle divide10 pm) and a microsyringe, which was connected to a microinjection system, was first constructed. With this system, micro gas sensor arrays could be successfully prepared on ITO electrodes. Two kinds of micro gas sensor films were prepared, based on polythiophene (PTh) and poly(3-n-dodecylthiophene) (PD). The response behavior of conventional PTh and micro-PTh films against NH3 at three different operating temperatures (25, 40 and 60degreesC) was investigated by measuring the resistance of the film. With the micro-PTh film, a reversible response was observed against NH3 when measured at 40 and 60degreesC. In addition, the responsive characteristics of the microsensor films against different testing gases were examined at the three operating temperatures. The resistance of the microsensor films of PTh and PD changed considerably, depending on the type of testing gas, allowing these sensor films to be used for the detection of various gases. Furthermore, the microsensor films had a high stability compared with conventional films prepared from the same polymer.
Monitoring the bioelectrochemical activity of living cells with sensor array-based microsystems represents an emerging technique in a large area of biomedical applications, ranging from basic research to various field...
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Monitoring the bioelectrochemical activity of living cells with sensor array-based microsystems represents an emerging technique in a large area of biomedical applications, ranging from basic research to various fields of pharmacological analyses. The main appeal is the ability of these miniaturised microsystems to perform, in real time, non-invasive in-vitro investigations of the physiological state of a cell population. In this paper, we present two different microsystems designed for multisite monitoring of the physiological state of a cell population. The first microsystem, intended for cellular metabolism monitoring, consists of an array of 12 spatially distributed ISFETs to detect small pH variations induced by the cell population. The second microsystem consists of an array of 40 ISFETs and 20 gold microelectrodes and it has been designed to monitor the electrical activity of neurons. This is achieved by direct coupling of the neuronal culture with the ISFET sensitive layer and by utilising gold microelectrodes for neuronal electrical stimulation. (C) 2001 Elsevier Science B.V. AU rights reserved.
Monitoring the bioelectrochemical activity of living cells with sensor array-based microsystems represents an emerging technique in a large area of biomedical applications, ranging from basic research to various field...
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Monitoring the bioelectrochemical activity of living cells with sensor array-based microsystems represents an emerging technique in a large area of biomedical applications, ranging from basic research to various fields of pharmacological analyses. The main appeal is the ability of these miniaturised microsystems to perform, in real time, non-invasive in-vitro investigations of the physiological state of a cell population. In this paper, we present two different microsystems designed for multisite monitoring of the physiological state of a cell population. The first microsystem, intended for cellular metabolism monitoring, consists of an array of 12 spatially distributed ISFETs to detect small pH variations induced by the cell population. The second microsystem consists of an array of 40 ISFETs and 20 gold microelectrodes and it has been designed to monitor the electrical activity of neurons. This is achieved by direct coupling of the neuronal culture with the ISFET sensitive layer and by utilising gold microelectrodes for neuronal electrical stimulation. (C) 2001 Elsevier Science B.V. AU rights reserved.
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