Calculations of temperature rise produced in body tissue by a spherical electrode

Two estimates of temperature rise produced in body tissue when a spherical electrode passes current have been calculated. The estimates bracket the expected temperature rise. Time-transient and steady-state results have been obtained. The effects of heat transfer through the highly conductive metal electrode and irreversible Faradaic reactions have been considered. The calculations indicate that electrodes smaller than about 2 micron in radius produce a peak temperature rise of about 1 degree C when driven by typical square current pulses of 25 microA intensity and 200 microseconds duration. The results are presented in a graphic form allowing for quick estimation of the expected peak temperature rise around electrodes of a specific radius, which are driven with a pulse of known current density and duration.