**4. The effective factors on gas sensor properties**

The following are the effective factors on gas sensor properties.


displaces the oxygen atoms which is related to the grain. This lowers the voltage barrier and thus lowers the resistance and conductivity increases. Since dopant increases the number of one type of carrier so the electrical conductivity depends on the number of atoms of the added material that is, focuses on free electrons generated from it [16]. The researcher Navaneethan M, et al., was able to study the improvement of sensitivity to ammonia gas sensor, as the sensitivity measurements for ammonia gas showed the highest response rate when Ag impregnation of ammonia gas [17].

