Metal electrodes in bioengineering.

The metal electrode is the critical interface between a measuring or stimulating device and the entity to be measured or stimulated. Electricity flows through wires by electron flow. It flows through tissue or fluid by ion flow. To produce an ion from an electron, a chemical reaction is necessary. This reaction occurs within a micron of the metal surface. It is a different reaction for an anode than for a cathode. It usually depends much more strongly on the metal chosen for the electrode than on the fluid or tissue electrolyte in which the electrode is immersed. In all cases, the reaction pair is strongly dependent on the quiescent voltage level of the system and on the magnitude of the voltage excursions around that level. This presentation will attempt to discuss the above points from the viewpoint of the researcher/designer who must use such metal electrodes to make practical measurements or who must connect practical stimulating devices to biophysical systems. The interdisciplinary field we will be discussing is "biophysical electrochemistry", and careful examination of each of these four component fields is necessary.