Sensors

215 KiB

Open AccessArticle

Near-UV Transmittance of Basalt Dust as an Analog of the Martian Regolith: Implications for Sensor Calibration and Astrobiology

by G. M. Muñoz Caro, E. Mateo-Martí and J. Martínez-Frías

Sensors 2006, 6(6), 688-696; https://doi.org/10.3390/s6060688 - 27 Jun 2006

Cited by 22 | Viewed by 9229

Abstract

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 [...] Read more.

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. Full article

► Show Figures

995 KiB

Open AccessReview

Wide Bandgap Semiconductor Nanorod and Thin Film Gas Sensors

by Byoung Sam Kang, Hung-Ta Wang, Li- Chia Tien, Fan Ren, Brent P. Gila, David P. Norton, Cammy R. Abernathy, Jenshan Lin and Stepehn J. Pearton

Sensors 2006, 6(6), 643-666; https://doi.org/10.3390/s6060643 - 24 Jun 2006

Cited by 67 | Viewed by 15405

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Gas Sensors)

► Show Figures

197 KiB

Open AccessArticle

A Microsystem Based on Porous Silicon-Glass Anodic Bonding for Gas and Liquid Optical Sensing

by Luca De Stefano, Krzysztof Malecki, Francesco G. Della Corte, Luigi Moretti, Ilaria Rea, Lucia Rotiroti and Ivo Rendina

Sensors 2006, 6(6), 680-687; https://doi.org/10.3390/s6060680 - 23 Jun 2006

Cited by 35 | Viewed by 11153

Abstract

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 [...] Read more.

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. Full article

► Show Figures

31 KiB

Open AccessEditorial

Introduction to the Special Issue on "Satellite Altimetry: New Sensors and New Applications"

by Graham Quartly and Ge Chen

Sensors 2006, 6(6), 616-619; https://doi.org/10.3390/s6060616 - 23 Jun 2006

Cited by 4 | Viewed by 5306

Abstract

Spaceborne radar altimeters provide information on the Earth's surface by transmitting a series of radio-frequency pulses and recording their echoes.[...] Full article

(This article belongs to the Special Issue Satellite Altimetry: New Sensors and New Application)

181 KiB

Open AccessArticle

Sensing Arrays Constructed from Nanoparticle Thin Films and Interdigitated Microelectrodes

by Lingyan Wang, Nancy N. Kariuki, Mark Schadt, Derrick Mott, Jin Luo, Chuan-Jian Zhong, Xiajing Shi, Chen Zhang, Weibing Hao, Susan Lu, Nam Kim and Jian-Q. Wang

Sensors 2006, 6(6), 667-679; https://doi.org/10.3390/s6060667 - 22 Jun 2006

Cited by 29 | Viewed by 9733

Abstract

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 [...] Read more.

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. Full article

► Show Figures

132 KiB

Open AccessArticle

A Rotating Knife-beam Altimeter for Wide-swath Remote Sensing of Ocean: Wind and Waves

by V. Yu. Karaev, M. B. Kanevsky, G. N. Balandina, E. M. Meshkov, P. Challenor, Meric Srokosz and C. Gommenginger

Sensors 2006, 6(6), 620-642; https://doi.org/10.3390/s6060620 - 22 Jun 2006

Cited by 14 | Viewed by 10419

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Satellite Altimetry: New Sensors and New Application)

► Show Figures

272 KiB

Open AccessReview

Cyclodextrin Derivatives as Chiral Supramolecular Receptors for Enantioselective Sensing

by Patrick Shahgaldian and Uwe Pieles

Sensors 2006, 6(6), 593-615; https://doi.org/10.3390/s6060593 - 22 Jun 2006

Cited by 114 | Viewed by 14717

Abstract

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 [...] Read more.

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. Full article

► Show Figures

290 KiB

Open AccessArticle

Development of an In-Fiber Nanocavity Towards Detection of Volatile Organic Gases

by Cesar Elosua, Ignacio R. Matias, Candido Bariain and Francisco J. Arregui

Sensors 2006, 6(6), 578-592; https://doi.org/10.3390/s6060578 - 16 Jun 2006

Cited by 31 | Viewed by 9202

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Gas Sensors)

► Show Figures

416 KiB

Open AccessReview

Further Structural Intelligence for Sensors Cluster Technology in Manufacturing

by Samir Mekid

Sensors 2006, 6(6), 557-577; https://doi.org/10.3390/s6060557 - 15 Jun 2006

Cited by 35 | Viewed by 11137

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Intelligent Sensors)

► Show Figures

176 KiB

Open AccessArticle

Differential Laser Doppler based Non-Contact Sensor for Dimensional Inspection with Error Propagation Evaluation

by Samir Mekid and Ketsaya Vacharanukul

Sensors 2006, 6(6), 546-556; https://doi.org/10.3390/s6060546 - 15 Jun 2006

Cited by 7 | Viewed by 9859

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Intelligent Sensors)

► Show Figures

Journal Menu

Journal Browser

Sensors, Volume 6, Issue 6 (June 2006) – 10 articles , Pages 546-696

Further Information

Guidelines

MDPI Initiatives

Follow MDPI