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 abse nce of interacting species at its surface. This phenomenon has been investi gated regarding possible analytical applications for the determination of h eavy metals in aqueous solutions. Therefore, microstructured polycrystallin e metal electrodes of gold (film thickness similar to 20 nm) were fabricate d 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 incr ease of the de resistance of the thin layer electrode, and the subsequent d issolution 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. (C) 2001 Elsevier Science B.V. All rights reserved.