Multi-channel stimulation required inserting a bundle of electrodes around the first turn of the cochlea, so that individual electrodes could lie close to the auditory nerve fibres for the place coding of frequencies. However, initially the electrode bundle could not pass an adequate distance, as it met the outer wall and its upward passage was limited by friction (top). A solution came when it was found that blades of grass which have a flexible tip and increasing stiffness passed around the basal turn of a shell which was a replicas of the human cochlea (centre). This was verified on the human cochlea, and also with modelling and biomechanical studies. In addition the electrode wires were terminated as bands around the carrier to reduce the friction against the other wall and allow safe electrical currents to be used (bottom). A sheath of tissue from the patient was placed around the electrode where it entered the cochlea to prevent infection passing from the middle to the inner ear with the risk of meningitis.