Effects of electrode size on the performance of neural recording microelectrodes

A significant factor in the optimisation of implantable electrodes for long-term neural recording is the effect electrode size has on the data collected. It is preferable to have as small an electrode as possible for improved selectivity (i.e. the ability to discriminate between different neurons), but reducing electrode size increases electrode impedance and thermal noise. Here, the authors present the results of a study of action potentials recorded from locusts in vivo. Signals recorded from electrodes of dimensions between 4/spl times/4 /spl mu/m and 50/spl times/50 /spl mu/m are presented, with analyses of action potentials and recorded noise. It is observed that there appears to be an optimum electrode size of about 20/spl times/20 /spl mu/m, which presents the best compromise between size and recording characteristics.