Please find the attachment

Several influencing factors of sensing, such as the characteristics and structure of the sensing layer, affect the redox reactions and thus decide the sensitivity of metal oxides as gas sensing materials. Among all sensors based on metal oxide semiconductors, the sensitivity of SnO2, ZnO, TiO2 etc based ones is relatively high, leading to its greater popularity. However, this high sensitivity is mainly based on the low working temperature, which is often realized through a preheated film for sensing at low temperature. For most metal oxide gas sensors, the low operating temperature is due to the reaction temperature of O2−. The sensitive layer has to be preheated to an elevated temperature (RT) in order to increase the probability of gas molecule adsorption on the layer surface which would consume ions of the sensing materials. As the ions are consumed, the conductivity of the film will increase to realize the sensing function. Besides the preheated film. Apart from this methods, there are also other methods like pre-concentration technology that could be applied to improve the sensitivity of gas sensors. Since methods like those do not affect the characteristics of composite sensing materials. For the methods changing materials’ characteristics, the use of composite materials such as SnO2-ZnO, ZnO-PANI, TiO2-PANI, ZnO, Fe2O3-PANI is also a good choice for improving metal oxide gas sensors’ sensitivity since they suggest a synergistic effect between the two components. In this method the sensitivity could be moderated by changing the proportions of each material in the composite.

Annealing is an important issue but adhesion and film thickness is the main parameters.

Annealing will affect the sensing properties- but necessarily improving. Since you deposit the film on a glass substrate, then make sure about using suitable preparation parameters.

You may check this:

Article Selective hydrogen gas sensor using CuFe2O4 nanoparticle bas...