High-performance humidity sensors based on high-field anodized porous alumina films

Improved humidity sensors based on porous anodized alumina (PAA) films were prepared via stable high-field anodization and subsequent isotropic chemical etching for appropriate times. The results reveal that sensitivity over a wide humidity range can be adjusted by changing the microstructure of the porous alumina layer, which can be explained in terms of the inhomogeneous distribution of anion impurities in the pore sidewall. The short response and recovery times obtained were ascribed to the ordered pore arrays and large pore size of the PAA films. This study has significance in tailoring the moisture sensitivity in the design of diverse sensors for practical applications.