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1

Chemically synthesized PbS nanoparticulate thin films for a rapid NO2 gas sensor

Burungale V. V., Devan R. S., Pawar S. A., Harale N. S., Patil V. L., Rao V. K., Ma Y. R., Ae J. E., Kim J. H., Patil P. S.

Materials Science Poland

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2016

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Vol. 34, No. 1

204--211

EN

Rapid NO2 gas sensor has been developed based on PbS nanoparticulate thin films synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR) method at different precursor concentrations. The structural and morphological properties were investigated by means of X-ray diffraction and field emission scanning electron microscope. NO2 gas sensing properties of PbS thin films deposited at different concentrations were tested. PbS film with 0.25 M precursor concentration showed the highest sensitivity. In order to optimize the operating temperature, the sensitivity of the sensor to 50 ppm NO2 gas was measured at different operating temperatures, from 50 to 200 degrees C. The gas sensitivity increased with an increase in operating temperature and achieved the maximum value at 150 degrees C, followed by a decrease in sensitivity with further increase of the operating temperature. The sensitivity was about 35 % for 50 ppm NO2 at 150 degrees C with rapid response time of 6 s. T90 and T10 recovery time was 97 s at this gas concentration.

2

Nanostruktury ZnO wytwarzane metodą elektroprzędzenia do zastosowań w detekcji gazów

Maziarz W

Elektronika : konstrukcje, technologie, zastosowania

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2013

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Vol. 54, nr 12

41-45

PL

Jednym z rozwijających się silnie nurtów badań w sensoryce jest poszukiwanie nowych materiałów gazoczułych o rozwiniętej powierzchni, występujących w postaci tzw. nanostruktur. Warstwy gazoczułe tego typu, zawierające elementy jednowymiarowe, pozwalają na szybką dyfuzję gazu w głąb materiału, co zwiększa szybkość reakcji takiego czujnika. Czujniki wykorzystujące nanostruktury pobierają znacznie mniejszą moc ze względu na mniejsze wymiary. Akceptowalną odpowiedź na gaz obserwuje się też w niższej temperaturze. W pracy zarysowano obecny stan badań nad materiałami gazoczułymi zawierającymi struktury w skali nano, ze szczególnym uwzględnieniem nanostruktur tlenku cynku domieszkowanych glinem, wytwarzanych przez autora metodą elektroprzędzenia. Uzyskane struktury złożone z sieci nanodrutów o średnicach 130-500 nm poddano podstawowym badaniom strukturalnym oraz elektrycznym. Stwierdzono dobrą czułość na tlenek azotu już w temperaturze ok. 160ºC, przy braku czułości na etanol.

EN

Nowadays one of the most important issues in gas sensors domain is searching for new materials that are smaller, have faster response, work at lower temperatures in comparison to conventional sensors and exhibit low power consumption. Devices manufactured from such materials can have built-in electronics and may be used in portable applications. The most popular are various nanomaterials manufactured with different technologies.The work presents the outline of current state of research of nanomaterials used in gas sensors. The author obtained ZnO nanostructures with electrospinning method. Investigation of ZnO:Al nanofibres with varying diameters revealed their good sensitivity to nitrogen dioxide at temperatures lower than these for conventional conductometric type sensors.

3

Signal processing system in cavity enhanced spectroscopy

Wojtas J., Bielecki Z.

Opto-Electronics Review

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2008

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Vol. 16, No. 4

420-427

EN

The paper presents a signal processing system used for nitrogen dioxide detection employing cavity enhanced absorption spectroscopy. In this system, the absorbing gas concentration is determined by the measurement of a decay time of a light pulse trapped in a cavity. The setup includes a resonance optical cavity, which was equipped with spherical and high reflectance mirrors, the pulsed diode laser (414 nm) and electronic signal processing system. In order to ensure registration of low-level signals and accurate decay time measurements, special preamplifier and digital signal processing circuit were developed. Theoretical analyses of main parameters of optical cavity and signal processing system were presented and especially signal-to-noise ratio was taken into consideration. Furthermore, investigation of S/N signal processing system and influence of preamplifier feedback resistance on the useful signal distortion were described. The aim of the experiment was to study potential application of cavity enhanced absorption spectroscopy for construction of fully optoelectronic NO₂ sensor which could replace, e.g., commonly used chemical detectors. Thanks to the developed signal processing system, detection limit of NO₂ sensor reaches the value of 0.2 ppb (absorption coefficient equivalent = 2.8 x 10 ⁻⁹ cm⁻¹ ).

4

NO2 optical fibre sensor based on porous glass probe

Dorosz D., Procyk B.

Molecular and Quantum Acoustics

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2008

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Vol. 29

65-72

EN

Nitrogen dioxide optical fibre sensor based on nanoporous glass probe was obtained. As a sensor probe glasses from the Na2O-B2O3-SiO2 system modified with TiO2 and ZrO2 and Al2O3 have been made. Porous glasses based on silica posses very good thermal and chemical durability, they are also transparent in the wide of spectrum range. It makes also possibility of use this kind of material as an optical sensor element, operating in hard working conditions. The presented design consists in the spectroscopic changes caused by the specific coloration reactions between NO2 and organic reagents placed in the nanopores. The presented different sensing reagents are compared and allow to achieve ppb NO2 level detection. High specific surface area (200 m2/g) and stable pores distribution in the size of obtained glasses assured good repeatability of the sensor.