Flexible Substrate Based Gas Sensors for Air Pollution Monitoring
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I7.14.1
Flexible Substrate Based Gas Sensors for Air Pollution Monitoring 1
S.Dmitriev, 1Gh.Duca, 2I. Dementiev, 1A.Craciun 'Department of Industrial and Environmental Chemistry, Moldova State University 2 Department of Physics, Moldova State University 60, A. Mateevici Str., Chisinau, MD-2009, Republic of Moldova
ABSTRACT
In the given report we present results of investigation of possibility to produce gas sensors on flexible substrates (polymer roll base). As gas sensitive materials were chosen glass chalcogenide semiconductors on the base of solid solutions of (As2S3)x-(As2Se3)1-x (where x=0; 0.3; 0.5; 0.7 and 1.0) and also solid solutions of As-Tl-S-Se system. Thin films of the mentioned above materials were deposited on lavsan roll film by means of thermal evaporation under vacuum conditions 10-5 Torr. At the thickness of 1-2 um the deposited layers are possessed the specific resistance in the range of 1010-1014 Ohm.cm on dependence on chemical composition. The change of conductivity of these films in the presence of gas impurity in atmosphere was used as sensitive parameter. Gas sensitive characteristics of obtained structures were tested with such toxic and inflammable environmental pollutant gases as carbon monoxide, methane, nitrogen dioxide, hydrogen and other. All measurements of gas sensitivity were performed at room temperature. For further increase of the gas sensitivity and selectivity the very thin layer of Pd was deposited onto the surface of semiconductor layer. The last one has allowed to increasing the gas sensitive characteristics by order. Through routine technology mode ready gas sensors were created. Dimensions of the developed gas sensitive elements were 1000x1000x350 µm. INTRODUCTION
The first attempts to implement flexible electronics were made still in 60’s and were directed on creation of passive and interconnect elements of electronic arrays or devices. Only in the late 90’s it became possible to fabricate active elements (such as, for example, thin film transistors) on the flexible substrate. As further progress of the flexible electronics the transition from the wafer to wafer process to roll to roll one could be considered. Fabrication of the integrated circuits on the flexible substrates by means of roll to roll process allows to significantly decreasing the manufacturing costs through higher throughput, and it may bring a revolution in the electronic manufacturing industry compared to the transition from the printing press to roll processing in typography. Currently, the basic application of this technology is concentrated in the flexible displays manufacturing but full advantages of flexible electronics technology will be seen at the realization of circuits and devices for very specific application. One of such scientific and applied directions is gas sensorics.
I7.14.2
Many research efforts aiming to develop innovative monitoring systems for the detection and measuring of concentrations of toxic and inflammable gases have been undertaken to substitute the standard analyti
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