Room temperature ionic liquids (RTILs) possess superior physical and chemical properties, such as thermal stability and a wide electrochemical potential window. Because of these advantages, RTILS offer potential as a new generation of electrochemical gas sensor electrolytes. 1- butyl-3-methyl imidazole tetrafluorborate ([BMIM][BF4]) has been proven to be a useful electrolyte for an oxygen sensor; however, the leakage problem of [BMIM][BF4] will corrode the circuit and reduce the life of the sensor. This is also inconvenient for the transportation of sensors. In this paper, by adding a polymer to RTILs, a microporous film was produced to improve the linearity of the sensor response to oxygen; as a result, the electrical properties surpass those of a solid polymer electrolyte. The double-layer ionic liquid film (DLILF) with excellent linear regression coefficient and stability was obtained by combining PMMA/IL microporous film with PVDF/IL microporous film. The linear regression coefficient (R-2) of plotted oxygen concentration vs. peak current is 0.995, although the response current of the electrolyte decreases. Our study indicates that the addition of RTILs to the mixture improves the electrical properties of the polymers and increases the linear relationship between the response current and oxygen concentration; the synergism of different polymers also enhances electrochemical oxygen sensor performance. (c) 2018 The Electrochemical Society.