A novel composite model is put forward for semiconductor humidity-sensitive ceramic material based on Maxwell-Garnett and effective medium theory

and analytical expression of the relation between effective refractive index and relative humidity is showed with different absorption factors and porosities.The lager the absorption factor is

the higher the refractive index is.Refractive index of humidity-sensitive film SiO2 decreases with the increase of ceramic material porosity.The sensitivity of optical humidity sensor is available to magnitude of 10-3.In contrast to the experimental humidity-sensing curve of Alberto A H et al

the analysis of mechanism

theoretical simulation is in agreement with experimental results.So this composite model is proved to be reasonable.