A novel surface plasmon resonance(SPR)trimethylamine(TAM)gas sensor structure coated a combined Ag and TiO2 film is proposed.The combined film is prepared by RF-reactive-sputtering deposition on rutile prism
and the thicknesss of Ag and TiO2 films are 50nm and 100nm
respectively.A gas sample cell is set up on the surface of the combined film.The phenomena of SPR occurs on the interfue of combined film under the excitation of He-Ne light.The experiments show that the SPR angle is almost linear with the TAM volume fraction.