Sensors

1010 KiB

Open AccessArticle

In-Situ Chemiresistor Sensor Package for Real-Time Detection of Volatile Organic Compounds in Soil and Groundwater

by Clifford K. Ho and Robert C. Hughes

Sensors 2002, 2(1), 23-34; https://doi.org/10.3390/s20100023 - 30 Jan 2002

Cited by 93 | Viewed by 14375

This paper presents the development of a real-time microsensor-based monitoring system that can be used to detect and characterize volatile organic compounds in soil and groundwater. The system employs an array of polymer-based microsensors (chemiresistors) packaged in a waterproof housing that is designed to protect the sensor from harsh subsurface environments, including completely water-saturated conditions. The sensors and packaging have been tested in field and laboratory environments, and characterization methods are being developed that utilize contaminant-transport models and time-dependent, in-situ sensor data to identify the location of the contaminant source. Full article

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90 KiB

Open AccessArticle

Surface Plasmon Resonance Studies on Molecular Imprinting

by Ping Li, Yan Huang, Junze Hu, Chunwei Yuan and Baoping Lin

Sensors 2002, 2(1), 35-40; https://doi.org/10.3390/s20100035 - 19 Jan 2002

Cited by 30 | Viewed by 8748

Abstract

The molecular imprinted polymer (MIP) members were fabricated with the print molecule L-phenylalanine ethyl ester. The elution and adsorption procedures were investigated by surface plasmon resonance in situ. The changes of refractive angle during elution procedure suggest that the MIP is prepared on [...] Read more.

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1101 KiB

Open AccessArticle

A (Bio-)Chemical Field-Effect Sensor with Macroporous Si as Substrate Material and a SiO₂ / LPCVD-Si₃N₄ Double Layer as pH Transducer

by Michael J. Schöning, Anette Simonis, Christian Ruge, Holger Ecken, Mattea Müller-Veggian and Hans Lüth

Sensors 2002, 2(1), 11-22; https://doi.org/10.3390/s20100011 - 15 Jan 2002

Cited by 43 | Viewed by 11529

Abstract

Macroporous silicon has been etched from n-type Si, using a vertical etching cell where no rear side contact on the silicon wafer is necessary. The resulting macropores have been characterised by means of Scanning Electron Microscopy (SEM). After etching, SiO₂was thermally grown on the top of the porous silicon as an insulating layer and Si₃N₄ was deposited by means of Low Pressure Chemical Vapour Deposition (LPCVD) as transducer material to fabricate a capacitive pH sensor. In order to prepare porous biosensors, the enzyme penicillinase has been additionally immobilised inside the porous structure. Electrochemical measurements of the pH sensor and the biosensor with an Electrolyte/Insulator/Semiconductor (EIS) structure have been performed in the Capacitance/Voltage (C/V) and Constant capacitance (ConCap) mode. Full article

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140 KiB

Open AccessArticle

Detection of Antioxidative Activity of Plant Extracts at the DNA-Modified Screen-Printed Electrode

by J. Labuda, M. Bučková, L. Heilerová, A. Čaniová-Žiaková, E. Brandšteterová, J. Mattusch and R. Wennrich

Sensors 2002, 2(1), 1-10; https://doi.org/10.3390/s20100001 - 15 Jan 2002

Cited by 36 | Viewed by 13057

Abstract

A simple procedure for the voltammetric detection of antioxidative activity of plant extracts based on the protection from DNA damage at the electrode surface is reported. A disposable electrochemical DNA biosensor fabricated as a carbon-based screen-printed electrode modified by a surface layer of the calf thymus double stranded (ds) DNA was used as a working electrode in combination with a silver/silver chloride reference electrode and a separate platinum auxiliary electrode. The [Co(phen)₃]³⁺ ion served as the dsDNA redox marker and the [Fe(EDTA)]- complex with hydrogen peroxide under the electrochemical reduction of the iron atom were used as the DNA cleavage mixture. A remarkable antioxidative activity of phenolic antioxidants such as rosmarinic and caffeic acids as standards and the extracts of lemon balm, oregano, thyme and agrimony was found which is quite in agreement with an antiradical activity determined spectrophotometrically using 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical. Full article

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Sensors, Volume 2, Issue 1 (January 2002) – 4 articles , Pages 1-40

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