Reducing insertion sites of penetrating multipolar shaft electrodes by double side electrode arrangement

Micromachined devices with substrate-integrated electrodes are the key component in implantable microdevices for recording neuronal signals or stimulating nerves. For basic investigations in central- and partially in peripheral-nerve structures, silicon based shaft electrodes have established as standard multichannel device. In this paper, we present polyimide based multichannel shaft electrodes with a total thickness of 15 /spl mu/m. The integration of interconnects and an interface to an commercially available connector made additional assembling techniques obsolete. An electrode arrangement on the front side and the back side of the shafts reduces the insertion sites at a given number of electrode channels. Areas on interest in the half planes left and right to the insertion site could be monitored with one device simultaneously. The double side shaft electrodes were inserted in the optic nerve of rats. First recordings were obtained from this acute implantation after visual stimulation of the corresponding eye with flash light.