SURFACE MODIFICATION OF PLATINUM THIN-FILM ELECTRODES TOWARDS A DEFINED ROUGHNESS AND MICROPOROSITY

The roughness and microporosity of platinum thin-film electrodes, whic h act as transducers in electrochemical biosensors, have been varied b y evaporating titanium or aluminum as top layers and subsequent anneal ing and etching of these metal films. This defined structural variatio n is very important in the field of chemo- and biosensors. The electro chemical characteristics of the electrode surface were investigated by cyclic voltammetry in 0.5 M H2SO4. From this the real electrode area was determined by calculating the charge density in the hydrogen adsor ption and desorption regions, and the roughness factor, defined as the ratio between the calculated charge density and the theoretical value of smooth polycrystalline platinum, covered a range from 1.1 to 8.85. The platinum surface was studied by cyclic voltammetry, laser-seconda ry-neutral-mass-spectroscopy and atomic force microscopy. (C) 1997 Els evier Science S.A.