INTRODUCTION TO BIOELECTRODES

Recent developments in experimental and applied methodology in biology and medicine have accentuated the significance of electrode theory and practice to the biological investigator. At the same time, electrochemistry continues to devote full attention to electrode processes. ’ Although these fields have recently followed divergent pathways, a small number of review papers and monographs have appeared from time to time which focus on mutual interrelationships.This interdisciplinary meeting is being held to assess current developments in electrochemistry as applicable to and applied in the biomedical field. The history of electrochemistry and bioelectric phenomena is linked by electrodes and electrode problems, particularly electrode polarization. The existence of secondary currents generated by polarization effects, designated as secondary because they were opposite in direction to the current of the voltaic pile which produced them, was first described in 1801. Gautherot pointed out that platinum or silver wires which were used to decompose saline and which were charged by a voltaic battery yielded an electric current of short duration after being cut off from this battery. Within two years, secondary currents were applied to neuromuscular physiology. Oersted found that platinum wires which had formed part of a voltaic circuit for a few instants could produce secondary currents which would cause muscular contractions in a frog. However, the term “polarization” and its origin are immersed in confusion. The first application of this term to electrode phenomena is attributed by Gaston Plante, the originator of the lead storage (secondary current) battery, to the 1826 paper of the eminent Swiss physicist, de la Rive. It is extraordinary to note, however, that nowhere in this paper does he mention the words “secondary current” or “polarization. ” Although de la Rive subsequently used the term polarization in explaining the electrode changes which generated secondary currents, he himself realized that this concept was erroneous. Not only did the term “polarization” originate in a misconception, but the effects it was supposed to describe were a continuing source of ambiguity and misunderstanding in explanations of the electrical changes sensed by electrodes. In the next few years, Becquerel, Peltier, and Matteuci elucidated the phenomenon of polarization and attributed it to the deposition of foreign materials or thin films of gas on the electrodes-i.e., ohmic polarization. Meanswhile, experiments on the physiological effects of electricity by Marianini, Nobili, and Matteuci were seriously impaired by polarization, there being erratic responses on the make and break of current. Matteuci was well aware of the difficulties imposed by polarization and, in 1843, gave a description of what we now recognize as activation polarization. Various explanations of the cause of secondary currents raised the question of whether the resistance to current flow was due solely to polarization of the electrodes or whether there was an added resistance or junction potential in the opposite sense generated at the liquid metal interface. De la Rive, Fechner, Schroeder and others concluded from their studies that there existed a Uebergangswiderstand or transition resistance to current flow; Ohm and Lenz denied * Current address: Maimonides Medical Center, 4802 10th Ave., Brooklyn, N. Y.