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A new kind of sandwich-like bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] samarium complex Sm[Pc*]2(Pc*=Pc(OC8H17)8) is used as film-forming material. Pure Sm[Pc*]2 and mixture of Sm[Pc*]2 and octadecanol(OA) deposited from both pure water and 10-4M Cd2+ subphases are investigated. It is found that a mixture of 1:3 Sm[Pc*]2:OA forms an excellent material for the fabrication of the gas-sensing Langmuir-Blodgett (LB) film by studying the film-forming characteristics. A new gas sensor has been fabricated by incorporating the multilayer LB film into the gate electrode of a metal-oxide-semiconductor field effect transistor, forming an array of charge-flow transistor. On the application of a gate voltage (VGS), greater than the threshold voltage (VTH), a delay was observed in the response of the drain current. This is due to the time taken for the resistive gas-sensing film to charge up to VGS. This delay characteristic was found to depend on the concentration of NO2. Results are presented showing that the device can detect reversibly the concentration of NO2 gas down to 5 ppm at room temperature.