An electrode up to 30 cm long may be required for signal derivation from the brainstem and other deeper parts of the brain. The depth and direction of the area to be measured are ensured by the use of a conductive steel tube, through which the electrode is introduced.
At the electrode lead points 16 or 24, with a platinum-iridium wire thickness of 40 microns, the diameter of the polyimide tube is 0.4-0.5 mm. These sizes are typical, but smaller sizes are possible. The end of the electrode is cylindrical and sealed with an epoxy resin hemisphere. The electrode is not suitable for piercing the dura. A rigid guide must be used to reach the target area to be examined.
• Electrode outer surface: 400 or 500 micron diameter polyimide tube.
• Lead points: platinum-iridium wire. Diameter: 15, 20, 25, 40 microns.
• Synthetic resin binder: implant grade epoxy resin.
• Connector: Omnetics, Precidip, etc. different types.