W pracy podjęto problem optycznej detekcji gazów H2 i NH3 czujnikiem światłowodowym. Czujnik wykorzystuje warstwową strukturę sensorową, wykonaną na włóknie światłowodowym, pozwalającą wykrywać i mierzyć stężenie gazowego wodoru i amoniaku. Do detekcji H2 wykorzystano struktury Pd/TMO (TMO ang. Transition Metal Oxide) obejmujące warstwę wykonaną z tlenku metalu przejściowego (TMO) pokrytą katalityczną warstwą palladu. Warstwa TMO jest warstwą chemochromiczną, której działanie polega na zmianie jej parametrów optycznych pod wpływem absorpcji atomowego wodoru. Kataliza wodoru cząsteczkowego na atomowy następuje w warstwie palladu. Do detekcji NH3 wykorzystano struktury interferencyjne wykonane z Nafionu. Nafion wskutek oddziaływania z NH3 zmienia swoje parametry optyczne zmieniając tym samym warunki interferencji światła. Struktury sensorowe wykorzystane w czujnikach światłowodowych są warstwowymi strukturami interferencyjnymi Fabry-Perot.
EN
The paper presents an optical-fiber hydrogen sensor and ammonia sensor. The H2 and NH3 sensor utilises a layered Fabry-Perot interferometer and includes chemical active the resonance cavity. In the present paper the authors suggest the idea of a gasochromic hydrogen sensor based on the structure of a layered Fabry-Perot interferometer located at the end of the standard multi-mode fiber. The resonance cavity is a layer of metal oxides (e.g. NiO, WO3) coated on a thin film of palladium (Pd). The sensor permits to detect and to measure the concentration of hydrogen in a gaseous medium. The idea of presented optical ammonia sensor is based on variations of reflected light spectra result from interactions of ammonia with sensing layer. The sensor head consists of Nafion layer as a resonance cavity, deposited on the face of the fibre. The optical ammonia gas sensor display a very fast response time and a fast regeneration time at room temperature.
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In the paper, a gas optoelectronic sensor based on interferometric structure has been presented. Active polymer NafionŽ layer deposited at the top of the optical fibre forms the Fabry?Perot interferometer. Interaction with gas changes the physical properties of sensing layer, hence the interference conditions are fulfilled for different wavelengths. Sensor performance for different humidity levels has been measured. The influence of humidity variations on sensing layer is investigated as well. In order to suppress the moisture induced instability of the sensor different inhibiting layers have been deposited and their performance has been investigated. In the paper, a wide investigation of the sensor in ammonia atmosphere has been shown.
The deposition possibility of the polymer based waveguides in low cost and relatively simple and repeatable process is presented in experimental results. The waveguide can be easily formed into Mach-Zehnder interferometer by photolithography. The numerical analysis using the beam propagation method yields very promising results of sensor interaction with ammonia. The aim of future work will be to deposit the desired interferometer and compare the efficiency of the sensor with computer analysis.
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In recent years organic semiconductors have been given attention in the field of active materials for gas sensor applications. In the paper the investigations of the optoelectronic sensor structure of ammonia were presented. The sensor head consists of polyaniline and Nafion layers deposited on the face of the telecommunication optical fiber. The elaborated sensor ructure in the form of Fabry-Perot interferometer is of the extremely small dimension - its thickness is of the order of 1 [mu]m. Many sensor structures of different combinations of the polyaniline and Nafion layers were constructed and investigated. The optimal solution seems to be the structures with small number of polianiline layers (up to three).