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Sensors, Volume 7, Issue 12 (December 2007), Pages 3012-3559

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Open AccessArticle Analysis of Mean Access Delay in Variable-Window CSM
Sensors 2007, 7(12), 3535-3559; https://doi.org/10.3390/s7123535
Received: 10 October 2007 / Accepted: 21 December 2007 / Published: 21 December 2007
Cited by 9 | PDF Full-text (375 KB) | HTML Full-text | XML Full-text
Abstract
The paper addresses the problem of the mean access delay characteristics in termof the channel load for networked sensor/control systems in LonWorks/EIA-709 technology.The system modelling is focused on the Media Access Control protocol that provides theload prediction and determines the key network characteristics.
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The paper addresses the problem of the mean access delay characteristics in termof the channel load for networked sensor/control systems in LonWorks/EIA-709 technology.The system modelling is focused on the Media Access Control protocol that provides theload prediction and determines the key network characteristics. The network model assumesthe consistency of load prediction between the nodes, and that the Transaction ControlSublayer does not introduce limitations on the data transmission. The latter means that thenumbers of concurrent outgoing transactions being in progress are unlimited. Furthermore, itis assumed that the destination addresses of transmitted messages are distributed rather thanconcentrated on particular nodes. The analytical approach based on Markov chains isapplied. The calculation of transition probabilities of the Markov chain is exemplified by theload scenario where all the transactions are acknowledged, unicast, and the optionalcollision detection is enabled. On the basis of the stochastic analysis, the probabilities of asuccessful transmission and collision, respectively, are computed. Furthermore, thenumerical results of the mean access delay are reported. The simulative validation ofanalytical results is provided. Full article
(This article belongs to the Special Issue Intelligent Sensors)
Open AccessReview Optical Fiber Sensing Using Quantum Dots
Sensors 2007, 7(12), 3489-3534; https://doi.org/10.3390/s7123489
Received: 19 November 2007 / Accepted: 20 December 2007 / Published: 21 December 2007
Cited by 76 | PDF Full-text (1618 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in the application of semiconductor nanocrystals, or quantumdots, as biochemical sensors are reviewed. Quantum dots have unique optical properties thatmake them promising alternatives to traditional dyes in many luminescence basedbioanalytical techniques. An overview of the more relevant progresses in the application
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Recent advances in the application of semiconductor nanocrystals, or quantumdots, as biochemical sensors are reviewed. Quantum dots have unique optical properties thatmake them promising alternatives to traditional dyes in many luminescence basedbioanalytical techniques. An overview of the more relevant progresses in the application ofquantum dots as biochemical probes is addressed. Special focus will be given toconfigurations where the sensing dots are incorporated in solid membranes and immobilizedin optical fibers or planar waveguide platforms. Full article
(This article belongs to the Special Issue Optical Biosensors)
Open AccessArticle Naked-eye and Selective Detection of Mercury (II) Ions in Mixed Aqueous Media Using a Cellulose-based Support
Sensors 2007, 7(12), 3481-3488; https://doi.org/10.3390/s7123481
Received: 8 November 2007 / Accepted: 20 December 2007 / Published: 21 December 2007
Cited by 36 | PDF Full-text (858 KB) | HTML Full-text | XML Full-text
Abstract
A test paper for high-selectivity detecting Hg2+ ions in mixed acetonitrile-watersolutions has been achieved using a bis(ferrocenyl) azine, as chromogenic chemosensormolecule, and a solid cellulose fibre, as a substrate. Depending on the amount of mercuryions in contact with the detecting molecule a
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A test paper for high-selectivity detecting Hg2+ ions in mixed acetonitrile-watersolutions has been achieved using a bis(ferrocenyl) azine, as chromogenic chemosensormolecule, and a solid cellulose fibre, as a substrate. Depending on the amount of mercuryions in contact with the detecting molecule a spectacular color change in the celluloseindicator is produced, being possible to determine the concentration of Hg2+ ions either bynaked eye or spectroscopically. Full article
(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)
Open AccessArticle Combination of On-line pH and Oxygen Transfer Rate Measurement in Shake Flasks by Fiber Optical Technique and Respiration Activity MOnitoring System (RAMOS)
Sensors 2007, 7(12), 3472-3480; https://doi.org/10.3390/s7123472
Received: 3 December 2007 / Accepted: 20 December 2007 / Published: 20 December 2007
Cited by 34 | PDF Full-text (312 KB) | HTML Full-text | XML Full-text
Abstract
Shake flasks are commonly used for process development in biotechnologyindustry. For this purpose a lot of information is required from the growth conditions duringthe fermentation experiments. Therefore, Anderlei et al. developed the RAMOS technology[1, 2], which proviedes on-line oxygen and carbondioxide transfer rates
[...] Read more.
Shake flasks are commonly used for process development in biotechnologyindustry. For this purpose a lot of information is required from the growth conditions duringthe fermentation experiments. Therefore, Anderlei et al. developed the RAMOS technology[1, 2], which proviedes on-line oxygen and carbondioxide transfer rates in shake flasks.Besides oxygen consumption, the pH in the medium also plays an important role for thesuccessful cultivation of micro-organisms and for process development. For online pHmeasurement fiber optical methods based on fluorophores are available. Here a combinationof the on-line Oxygen Transfer Rate (OTR) measurements in the RAMOS device with anon-line, fiber optical pH measurement is presented. To demonstrate the application of thecombined measurement techniques, Escherichia coli cultivations were performed and on-line pH measurements were compared with off-line samples. The combination of on-lineOTR and pH measurements gives a lot of information about the cultivation and, therefore, itis a powerful technique for monitoring shake flask experiments as well as for processdevelopment. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Based pH Sensors)
Open AccessArticle Use of a Dynamic Enclosure Approach to Test the Accuracy of the NDIR Sensor: Evaluation Based on the CO2 Equilibration Pattern
Sensors 2007, 7(12), 3459-3471; https://doi.org/10.3390/s7123459
Received: 7 November 2007 / Accepted: 19 December 2007 / Published: 20 December 2007
Cited by 3 | PDF Full-text (351 KB) | HTML Full-text | XML Full-text
Abstract
As part of a quality assurance (QA) study for sensor systems, an enclosureapproach is applied to assess the accuracy of non-dispersive infrared (NDIR)-based CO2sensors. To examine the performance of the sensor system, an enclosure chambercontaining six sensor units of the two
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As part of a quality assurance (QA) study for sensor systems, an enclosureapproach is applied to assess the accuracy of non-dispersive infrared (NDIR)-based CO2sensors. To examine the performance of the sensor system, an enclosure chambercontaining six sensor units of the two model types (B-530 and H-500) was equilibratedwith calibrated CO2 standards at varying concentration levels. Initially, the equilibrationpattern was analyzed by CO2-free gas (0 ppm) at varying flow rates (i.e., 100, 200, 500, and1000 mL min-1). Results of the test yielded a highly predictable and quantifiable empiricalrelationship as a function of such parameters as CO2 concentration, flow rate, andequilibration time for the enclosure system. Hence, when the performance of the NDIR-method was evaluated at other concentrations (i.e., 500 and 1000 ppm), all the sensor unitsshowed an excellent compatibility, at least in terms of the correlation coefficients (r >0.999, p = 0.01). According to our analysis, the NDIR sensor system seems to attain anoverall accuracy near the 5% level. The relative performance of the NDIR sensor for CO2analysis is hence comparable with (or superior to) other methods previously investigated.The overall results of this study indicate that NDIR sensors can be used to provide highlyaccurate and precise analyses of CO2 both in absolute and relative terms. Full article
(This article belongs to the Special Issue Sensors for Urban Environmental Monitoring)
Open AccessReview An Overview of Label-free Electrochemical Protein Sensors
Sensors 2007, 7(12), 3442-3458; https://doi.org/10.3390/s7123442
Received: 4 December 2007 / Accepted: 18 December 2007 / Published: 20 December 2007
Cited by 101 | PDF Full-text (666 KB) | HTML Full-text | XML Full-text
Abstract
Electrochemical-based protein sensors offer sensitivity, selectivity and reliabilityat a low cost, making them very attractive tools for protein detection. Although the sensorsuse a broad range of different chemistries, they all depend on the solid electrode surface,interactions with the target protein and the molecular
[...] Read more.
Electrochemical-based protein sensors offer sensitivity, selectivity and reliabilityat a low cost, making them very attractive tools for protein detection. Although the sensorsuse a broad range of different chemistries, they all depend on the solid electrode surface,interactions with the target protein and the molecular recognition layer. Traditionally, redoxenzymes have provided the molecular recognition elements from which target proteins haveinteracted with. This necessitates that the redox-active enzymes couple with electrodesurfaces and usually requires the participation of added diffusional components, or assemblyof the enzymes in functional chemical matrices. These complications, among many others,have seen a trend towards non-enzymatic-based electrochemical protein sensors. Severalelectrochemical detection approaches have been exploited. Basically, these have fallen intotwo categories: labeled and label-free detection systems. The former rely on a redox-activesignal from a reporter molecule or a label, which changes upon the interaction of the targetprotein. In this review, we discuss the label-free electrochemical detection of proteins,paying particular emphasis to those that exploit intrinsic redox-active amino acids. Full article
Open AccessArticle Determination of Primary Spectral Bands for Remote Sensing of Aquatic Environments
Sensors 2007, 7(12), 3428-3441; https://doi.org/10.3390/s7123428
Received: 5 November 2007 / Accepted: 17 December 2007 / Published: 20 December 2007
Cited by 43 | PDF Full-text (632 KB) | HTML Full-text | XML Full-text
Abstract
About 30 years ago, NASA launched the first ocean-color observing satellite:the Coastal Zone Color Scanner. CZCS had 5 bands in the visible-infrared domain with anobjective to detect changes of phytoplankton (measured by concentration of chlorophyll) inthe oceans. Twenty years later, for the same
[...] Read more.
About 30 years ago, NASA launched the first ocean-color observing satellite:the Coastal Zone Color Scanner. CZCS had 5 bands in the visible-infrared domain with anobjective to detect changes of phytoplankton (measured by concentration of chlorophyll) inthe oceans. Twenty years later, for the same objective but with advanced technology, theSea-viewing Wide Field-of-view Sensor (SeaWiFS, 7 bands), the Moderate-ResolutionImaging Spectrometer (MODIS, 8 bands), and the Medium Resolution ImagingSpectrometer (MERIS, 12 bands) were launched. The selection of the number of bands andtheir positions was based on experimental and theoretical results achieved before thedesign of these satellite sensors. Recently, Lee and Carder (2002) demonstrated that foradequate derivation of major properties (phytoplankton biomass, colored dissolved organicmatter, suspended sediments, and bottom properties) in both oceanic and coastalenvironments from observation of water color, it is better for a sensor to have ~15 bands inthe 400 – 800 nm range. In that study, however, it did not provide detailed analysesregarding the spectral locations of the 15 bands. Here, from nearly 400 hyperspectral (~ 3-nm resolution) measurements of remote-sensing reflectance (a measure of water color)taken in both coastal and oceanic waters covering both optically deep and optically shallowwaters, first- and second-order derivatives were calculated after interpolating themeasurements to 1-nm resolution. From these derivatives, the frequency of zero values foreach wavelength was accounted for, and the distribution spectrum of such frequencies wasobtained. Furthermore, the wavelengths that have the highest appearance of zeros wereidentified. Because these spectral locations indicate extrema (a local maximum orminimum) of the reflectance spectrum or inflections of the spectral curvature, placing the bands of a sensor at these wavelengths maximizes the potential of capturing (and then restoring) the spectral curve, and thus maximizes the potential of accurately deriving properties of the water column and/or bottom of various aquatic environments with a multi-band sensor. Full article
(This article belongs to the Special Issue Ocean Remote Sensing)
Open AccessArticle Satellite-based Flood Modeling Using TRMM-based Rainfall Products
Sensors 2007, 7(12), 3416-3427; https://doi.org/10.3390/s7123416
Received: 30 November 2007 / Accepted: 18 December 2007 / Published: 20 December 2007
Cited by 37 | PDF Full-text (422 KB) | HTML Full-text | XML Full-text
Abstract
Increasingly available and a virtually uninterrupted supply of satellite-estimatedrainfall data is gradually becoming a cost-effective source of input for flood predictionunder a variety of circumstances. However, most real-time and quasi-global satelliterainfall products are currently available at spatial scales ranging from 0.25o to
[...] Read more.
Increasingly available and a virtually uninterrupted supply of satellite-estimatedrainfall data is gradually becoming a cost-effective source of input for flood predictionunder a variety of circumstances. However, most real-time and quasi-global satelliterainfall products are currently available at spatial scales ranging from 0.25o to 0.50o andhence, are considered somewhat coarse for dynamic hydrologic modeling of basin-scaleflood events. This study assesses the question: what are the hydrologic implications ofuncertainty of satellite rainfall data at the coarse scale? We investigated this question onthe 970 km2 Upper Cumberland river basin of Kentucky. The satellite rainfall productassessed was NASA’s Tropical Rainfall Measuring Mission (TRMM) Multi-satellitePrecipitation Analysis (TMPA) product called 3B41RT that is available in pseudo real timewith a latency of 6-10 hours. We observed that bias adjustment of satellite rainfall data canimprove application in flood prediction to some extent with the trade-off of more falsealarms in peak flow. However, a more rational and regime-based adjustment procedureneeds to be identified before the use of satellite data can be institutionalized among floodmodelers. Full article
(This article belongs to the Special Issue Remote Sensing of Land Surface Properties, Patterns and Processes)
Open AccessArticle Six-Degree-of-Freedom Sensor Fish Design and Instrumentation
Sensors 2007, 7(12), 3399-3415; https://doi.org/10.3390/s7123399
Received: 27 November 2007 / Accepted: 18 December 2007 / Published: 19 December 2007
Cited by 30 | PDF Full-text (1609 KB) | HTML Full-text | XML Full-text
Abstract
Fish passing through dams may be injured or killed despite advances in turbinedesign, project operations and other fish bypass systems. The six-degree-of-freedom (6DOF)Sensor Fish device is an autonomous sensor package that characterizes the physical conditionsand physical stresses to which fish are exposed when
[...] Read more.
Fish passing through dams may be injured or killed despite advances in turbinedesign, project operations and other fish bypass systems. The six-degree-of-freedom (6DOF)Sensor Fish device is an autonomous sensor package that characterizes the physical conditionsand physical stresses to which fish are exposed when they pass through complex hydraulicenvironments. It has been used to identify the locations and operations where conditions aresevere enough to injure or kill fish. During the design process, a set of governing equationsof motion for the Sensor Fish was derived and simulated to understand the design implica-tions of instrument selection and placement within the body of the device. The Sensor Fishpackage includes three rotation sensors, three acceleration sensors, a pressure sensor, and atemperature sensor with a sampling frequency of 2,000 Hz. Its housing is constructed of clearpolycarbonate plastic. It is 24.5 mm in diameter and 90 mm in length and weighs about 43 g,similar to the size and density of a yearling salmon smolt. The accuracy of the pressure sensorwas determined to be within 0.2 psi. In laboratory acceptance tests, the relative errors of boththe linear acceleration and angular velocity measurements were determined to be less than5%. An exposure is defined as a significant event when the acceleration reaches predefinedthresholds. Based on the different characteristic of acceleration and rotation velocities, theexposure event is categorized as either a collision between the Sensor Fish and a solid struc-ture or shear caused by turbulence. Since its development in 2005, the 6DOF Sensor Fish hasbeen deployed successfully at many major dams in the United States. Full article
Open AccessArticle A Novel Pulse Measurement System by Using Laser Triangulation and a CMOS Image Sensor
Sensors 2007, 7(12), 3366-3385; https://doi.org/10.3390/s7123366
Received: 2 November 2007 / Accepted: 18 December 2007 / Published: 19 December 2007
Cited by 40 | PDF Full-text (2246 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a novel, non-invasive, non-contact system to measure pulsewaveforms of artery via applying laser triangulation method to detect skin surfacevibration. The proposed arterial pulsation measurement (APM) system chiefly consists of alaser diode and a low cost complementary metal-oxide semiconductor (CMOS) imagesensor.
[...] Read more.
This paper presents a novel, non-invasive, non-contact system to measure pulsewaveforms of artery via applying laser triangulation method to detect skin surfacevibration. The proposed arterial pulsation measurement (APM) system chiefly consists of alaser diode and a low cost complementary metal-oxide semiconductor (CMOS) imagesensor. Laser triangulation and centroid method are combined with the Fast FourierTransform (FFT) in this study. The shape and frequency of the arterial pulsation can bedetected rapidly by using our APM system. The relative variation of the pulse at differentmeasurement points near wrist joint is used as a prognostic guide in traditional Chinesemedicine (TCM). An extensive series of experiments was conducted to evaluate theperformance of the designed APM system. From experimental results, the pulse amplitudeand frequency at the Chun point (related to the small intestine) of left hand showed anobvious increase after having food. In these cases, the peak to peak amplitudes and thefrequencies of arterial pulsations range from 38 to 48 μm and from 1.27 to 1.35 Hz,respectively. The height of arterial pulsations on the area near wrist joint can be estimatedwith a resolution of better than 4 μm. This research demonstrates that applying a CMOSimage sensor in designing a non-contact, portable, easy-to-use, low cost pulse measurementsystem is feasible. Also, the designed APM system is well suited for evaluating and pre-diagnosing the health of a human being in TCM clinical practice. Full article
(This article belongs to the Special Issue Integrated High-performance Imagers)
Open AccessArticle Lidar-based Studies of Aerosol Optical Properties Over Coastal Areas
Sensors 2007, 7(12), 3347-3365; https://doi.org/10.3390/s7123347
Received: 1 November 2007 / Accepted: 17 December 2007 / Published: 19 December 2007
Cited by 3 | PDF Full-text (239 KB) | HTML Full-text | XML Full-text
Abstract
Aerosol size distribution and concentration strongly depend on wind speed,direction, and measuring point location in the marine boundary layer over coastal areas.The marine aerosol particles which are found over the sea waves in high wind conditionsaffect visible and near infrared propagation for paths
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Aerosol size distribution and concentration strongly depend on wind speed,direction, and measuring point location in the marine boundary layer over coastal areas.The marine aerosol particles which are found over the sea waves in high wind conditionsaffect visible and near infrared propagation for paths that pass very close to the surface aswell as the remote sensing measurements of the sea surface. These particles are producedby various air sea interactions. This paper presents the results of measurements taken atnumerous coastal stations between 1992 and 2006 using an FLS-12 lidar system togetherwith other supporting instrumentation. The investigations demonstrated that near-waterlayers in coastal areas differ significantly from those over open seas both in terms ofstructure and physical properties. Taking into consideration the above mentioned factors,aerosol concentrations and optical properties were determined in the marine boundary layeras a function of offshore distance and altitude at various coastal sites in two seasons. Thelidar results show that the remote sensing algorithms used currently in coastal areas needverification and are not fully reliable. Full article
(This article belongs to the Special Issue Ocean Remote Sensing)
Open AccessArticle pH Sensitivity of Novel PANI/PVB/PS3 Composite Films
Sensors 2007, 7(12), 3329-3346; https://doi.org/10.3390/s7123329
Received: 29 November 2007 / Accepted: 18 December 2007 / Published: 19 December 2007
Cited by 26 | PDF Full-text (480 KB) | HTML Full-text | XML Full-text
Abstract
This paper reports on the results from the investigation into the pH sensitivity ofnovel PANI/PVB/PS3 composite films. The conductimetric sensing mode was chosen as itis one of the most promising alternatives to the mainstream pH-sensing methods and it is theleast investigated due to
[...] Read more.
This paper reports on the results from the investigation into the pH sensitivity ofnovel PANI/PVB/PS3 composite films. The conductimetric sensing mode was chosen as itis one of the most promising alternatives to the mainstream pH-sensing methods and it is theleast investigated due to the popularity of other approaches. The films were deposited usingboth screen-printing and a drop-coating method. It was found that the best response to pHwas obtained from the screen-printed thick films, which demonstrated a change inconductance by as much as three orders of magnitude over the pH range pH2-pH11. Thedevices exhibited a stable response over 96 hours of operation. Several films were immersedin buffer solutions of different pH values for 96 hours and these were then investigated usingXPS. The resulting N 1s spectra for the various films confirmed that the change inconductance was due to deprotonation of the PANI polymer backbone. SEM andProfilometry were also undertaken and showed that no considerable changes in themorphology of the films took place and that the films did not swell or contract due toexposure to test solutions. Full article
(This article belongs to the Special Issue State-of-the-Art Polymer Based pH Sensors)
Open AccessArticle Evaluation of Grassland Dynamics in the Northern-Tibet Plateau of China Using Remote Sensing and Climate Data
Sensors 2007, 7(12), 3312-3328; https://doi.org/10.3390/s7123312
Received: 13 October 2007 / Accepted: 14 December 2007 / Published: 17 December 2007
Cited by 27 | PDF Full-text (591 KB) | HTML Full-text | XML Full-text
Abstract
The grassland ecosystem in the Northern-Tibet Plateau (NTP) of China is verysensitive to weather and climate conditions of the region. In this study, we investigate thespatial and temporal variations of the grassland ecosystem in the NTP using theNOAA/AVHRR ten-day maximum NDVI composite data
[...] Read more.
The grassland ecosystem in the Northern-Tibet Plateau (NTP) of China is verysensitive to weather and climate conditions of the region. In this study, we investigate thespatial and temporal variations of the grassland ecosystem in the NTP using theNOAA/AVHRR ten-day maximum NDVI composite data of 1981-2001. The relationshipsamong Vegetation Peak-Normalized Difference Vegetation Index (VP-NDVI) and climatevariables were quantified for six counties within the NTP. The notable and unevenalterations of the grassland in response to variation of climate and human impact in theNTP were revealed. Over the last two decades of the 20th century, the maximum greennessof the grassland has exhibited high increase, slight increase, no-change, slight decrease andhigh decrease, each occupies 0.27%, 8.71%, 77.27%, 13.06% and 0.69% of the total area ofthe NTP, respectively. A remarkable increase (decrease) in VP-NDVI occurred in thecentral-eastern (eastern) NTP whereas little change was observed in the western andnorthwestern NTP. A strong negative relationship between VP-NDVI and ET0 was foundin sub-frigid, semi-arid and frigid- arid regions of the NTP (i.e., Nakchu, Shantsa, Palgonand Amdo counties), suggesting that the ET0 is one limiting factor affecting grasslanddegradation. In the temperate-humid, sub-frigid and sub-humid regions of the NTP (Chaliand Sokshan counties), a significant inverse correlation between VP-NDVI and populationindicates that human activities have adversely affected the grassland condition as waspreviously reported in the literature. Results from this research suggest that the alterationand degradation of the grassland in the lower altitude of the NTP over the last two decades of the 20th century are likely caused by variations of climate and anthropogenic activities. Full article
(This article belongs to the Special Issue Remote Sensing of Natural Resources and the Environment)
Open AccessArticle Gold Nanoparticles With Special Shapes: Controlled Synthesis, Surface-enhanced Raman Scattering, and The Application in Biodetection
Sensors 2007, 7(12), 3299-3311; https://doi.org/10.3390/s7123299
Received: 12 November 2007 / Accepted: 12 December 2007 / Published: 14 December 2007
Cited by 103 | PDF Full-text (1409 KB) | HTML Full-text | XML Full-text
Abstract
Specially shaped gold nanoparticles have intrigued considerable attention becausethey usually possess high-sensitivity surface-enhanced Raman scattering (SERS) and thusresult in large advantages in trace biodetermination. In this article, starch-capped goldnanoparticles with hexagon and boot shapes were prepared through using a nontoxic andbiologically benign aqueous-phase
[...] Read more.
Specially shaped gold nanoparticles have intrigued considerable attention becausethey usually possess high-sensitivity surface-enhanced Raman scattering (SERS) and thusresult in large advantages in trace biodetermination. In this article, starch-capped goldnanoparticles with hexagon and boot shapes were prepared through using a nontoxic andbiologically benign aqueous-phase synthetic route. Shape effects of gold nanoparticles onSERS properties were mainly investigated, and found that different-shaped goldnanoparticles possess different SERS properties. Especially, the boot-shaped nanoparticlescould induce more 100-fold SERS enhancements in sensitivity as compared with those fromgold nanospheres. The extremely strong SERS properties of gold nanoboots have beensuccessfully applied to the detection of avidin. The unique nanoboots with high-sensitivitySERS properties are also expected to find use in many other fields such as biolabel,bioassay, biodiagnosis, and even clinical diagnosis and therapy. Full article
Open AccessArticle From Hearing to Listening: Design and Properties of an Actively Tunable Electronic Hearing Sensor
Sensors 2007, 7(12), 3287-3298; https://doi.org/10.3390/s7123287
Received: 5 December 2007 / Accepted: 13 December 2007 / Published: 14 December 2007
Cited by 18 | PDF Full-text (1581 KB) | HTML Full-text | XML Full-text
Abstract
An important step towards understanding the working principles of the mammalian hearing sensor is the concept of an active cochlear amplifier. Theoretical arguments and physiological measurements suggest that the active cochlear amplifiers originate from systems close to a Hopf bifurcation. Efforts to model
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An important step towards understanding the working principles of the mammalian hearing sensor is the concept of an active cochlear amplifier. Theoretical arguments and physiological measurements suggest that the active cochlear amplifiers originate from systems close to a Hopf bifurcation. Efforts to model the mammalian hearing sensor on these grounds have, however, either had problems in reproducing sufficiently close essential aspects of the biological example (Magnasco, M.O. Phys. Rev. Lett. 90, 058101 (2003); Duke, T. & Jülicher, F. Phys. Rev. Lett. 90, 158101 (2003)), or required complicated spatially coupled differential equation systems that are unfeasible for transient signals (Kern, A. & Stoop, R. Phys. Rev. Lett. 91, 128101 (2003)). Here, we demonstrate a simple system of electronically coupled Hopf amplifiers that not only leads to the desired biological response behavior, but also has real-time capacity. The obtained electronic Hopf cochlea shares all salient signal processing features exhibited by the mammalian cochlea and thus provides a simple and efficient design of an artificial mammalian hearing sensor. Full article
(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Switzerland)
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