Platinum electrode noise in the ENG spectrum.

The noise from Pt electrodes has not been measured before. We measured the impedance and noise between pairs of Pt electrodes in cylindrical cells within frequency bands which contain the electroneurogram band (ENG, 500-10 kHz). The results show that the noise from the Pt-saline interface and also the volume conductor are the same as the thermal noise from the real part of those impedances. This means that Pt electrodes are convenient for neural recording because the total source noise from the electrodes and the volume conductor (tissue) can be estimated from the measured total impedance and calculating the thermal noise associated with the resistive part. This differs from Ag/AgCl electrodes for which the interface noise has been reported to be higher than the thermal noise, and therefore calculation of the total noise will be more difficult.