Two sets of electrode arrays made of either 25- or 50-μm-diameter Teflon-insulated platinum-iridium wire and Teflon have been developed for chronic intracortical electrical stimulation. It is concluded that a chronic intracortical stimulating electrodes should have the following properties: 1) the penetrating electrodes and supporting substrate must be stiff (to maintain interelectrode spacings upon implantation), and 2) the percutaneous leads must be extremely flexible (to avoid array movement after implantation).
