Voltohmmetry — a novel sensing principle for heavy metal determination in aqueous solutions

The lateral resistance of a thin metal film depends on the presence or absence of interacting species at its surface. This phenomenon has been investigated regarding possible analytical applications for the determination of heavy metals in aqueous solutions. Therefore, microstructured polycrystalline metal electrodes of gold (film thickness∼20 nm) were fabricated by silicon planar technology and their resistance–potential behaviour was measured during the electrochemical deposition and dissolution of selected heavy metals, such as Cd, Pb, Ni, Tl and Zn. The deposition causes an increase of the dc resistance of the thin layer electrode, and the subsequent dissolution of the deposited heavy metal species decreases the resistance to its initial value. Since both processes have been registered in dependence of the applied electrode potential, we introduce this sensing principle as voltohmmetry.