“…Compared to other sensing materials, metal oxide semiconductors possess low cost, simple construction, small size, and easy installation. Recently, with the advantages of large surface area, high surface to volume ratio, and special physicochemical properties, metallic oxide nanostructures such as SnO 2, TiO 2 , ZnO and CeO 2 have attracted wide interest for being used as humidity sensing materials [8][9][10][11] . Although lots of progresses on humidity sensors have been obtained, there are still some shortcomings in humidity sensitive materials such as low response speed and poor stability.…”