Sensors

682 KiB

Open AccessReview

Aspartate Aminotransferase (AST/GOT) and Alanine Aminotransferase (ALT/GPT) Detection Techniques

by Xing-Jiu Huang, Yang-Kyu Choi, Hyung-Soon Im, Oktay Yarimaga, Euisik Yoon and Hak-Sung Kim

Sensors 2006, 6(7), 756-782; https://doi.org/10.3390/s6070756 - 31 Jul 2006

Cited by 365 | Viewed by 46519

The levels of aspartate aminotransferase (AST/GOT) and alanineaminotransferase (ALT/GPT) in serum can help people diagnose body tissues especially theheart and the liver are injured or not. This article provides a comprehensive review ofresearch activities that concentrate on AST/GOT and ALT/GPT detection techniques due totheir clinical importance. The detection techniques include colorimetric, spectrophotometric,chemiluminescence, chromatography, fluorescence and UV absorbance, radiochemical, andelectrochemical techniques. We devote the most attention on experimental principle. Insome methods a few representative devices and important conclusions are presented. Full article

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155 KiB

Open AccessArticle

A Comparison of Frequency Pullability in Oscillators Using a Single AT-Cut Quartz Crystal and Those Using Two Single AT- Cut Crystals Connected in Parallel with a Series Load Capacitance or Series Load Inductance

by Vojko Matko

Sensors 2006, 6(7), 746-755; https://doi.org/10.3390/s6070746 - 29 Jul 2006

Cited by 11 | Viewed by 9122

Abstract

This paper presents a comparison of frequency pullability in oscillators using asingle AT-cut crystal and those using two single AT-cut crystals connected in paralleloperated with a series load capacitance or series load inductance at fundamental frequenciesof 4, 10 and 19 MHz. Pullability describes how the operating frequency may be changed byvarying the load capacitance. The paper also gives impedance circuits for both single- anddual-crystal units. The experiment results show that the new approach using two singlequartz crystals connected in parallel increases the frequency pulling range by 30-200% pending on the type of oscillator. Also given is the crystal frequency stability at thesethree frequencies. Full article

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266 KiB

Open AccessArticle

Mathematical Modeling of Plate−gap Biosensors with an Outer Porous Membrane

by Romas Baronas, Feliksas Ivanauskas, Irmantas Kaunietis and Valdas Laurinavicius

Sensors 2006, 6(7), 727-745; https://doi.org/10.3390/s6070727 - 24 Jul 2006

Cited by 17 | Viewed by 7482

Abstract

A plate−gap model of a porous enzyme doped electrode covered by a porousinert membrane has been proposed and analyzed. The two−dimensional−in−spacemathematical model of the plate−gap biosensors is based on the reaction−diffusionequations containing a nonlinear term related to the Michaelis−Menten kinetics. Usingnumerical simulation of the biosensor action, the influence of the geometry of the outermembrane on the biosensor response was investigated at wide range of analyteconcentrations as well as of the reaction rates. The numerical simulation was carried outusing finite−difference technique. The behavior of the plate−gap biosensors was comparedwith that of a flat electrode deposited with a layer of enzyme and covered with the sameouter membrane. Full article

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378 KiB

Open AccessArticle

A Miniaturized Magnetic Induction Sensor Using Geomagnetism for Turn Count of Small-Caliber Ammunition

by Sang-Hee Yoon, Seok-Woo Lee, Young-Ho Lee and Jong-Soo Oh

Sensors 2006, 6(7), 712-726; https://doi.org/10.3390/s6070712 - 24 Jul 2006

Cited by 14 | Viewed by 13050

Abstract

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

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130 KiB

Open AccessArticle

Improving the Response of a Load Cell by Using Optimal Filtering

by Wilmar Hernandez

Sensors 2006, 6(7), 697-711; https://doi.org/10.3390/s6070697 - 21 Jul 2006

Cited by 41 | Viewed by 14871

Abstract

Load cells are transducers used to measure force or weight. Despite the fact thatthere is a wide variety of load cells, most of these transducers that are used in the weighingindustry are based on strain gauges. In this paper, an s-beam load cell based on strain gaugeswas suitably assembled to the mechanical structure of several seats of a bus underperformance tests and used to measure the resistance of their mechanical structure to tensionforces applied horizontally to the seats being tested. The load cell was buried in a broad-band noise background where the unwanted information and the relevant signal sometimesshare a very similar frequency spectrum and its performance was improved by using arecursive least-squares (RLS) lattice algorithm. The experimental results are satisfactoryand a significant improvement in the signal-to-noise ratio at the system output of 27 dB wasachieved, which is a good performance factor for judging the quality of the system. Full article

(This article belongs to the Special Issue Intelligent Sensors)

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Sensors, Volume 6, Issue 7 (July 2006) – 5 articles , Pages 697-782

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