Development of nanoporous aao based capacitive-type sensors for heavy metal ion (arsenic) sensing application

In this work the evolution of a capacitive type sensor based on nanoporous anodic aluminum oxide (AAO) fabricated by a two-step anodization process using a low-cost customized setup designed in-house is reported. The parallel plate capacitors were fabricated using aluminum (Al) as base electrode and gold as top electrode, where the porous AAO was used as the dielectric material. This demonstrated the clear dependence of the capacitance values of the as prepared different sensors on the dielectric material's thickness. The as developed sensors were tested for the detection of arsenic (As) ions. An increase in the capacitance was observed while increasing the concentration of the As ion in aqueous solutions. The presence of As ion was confirmed through EDS (Energy dispersive X-ray spectroscopy) mapping carried out in a FESEM. This change in capacitance can be attributed to the change in dielectric constant of the active material with the incorporation of metal ions.