above the buffer 38 is coated onto the fiber immediately upon drawing of the fiber to preserve the strength of the fiber protecting it from environmental elements such as atmospheric moisture that can attack the glass silica surface and introduce fine cracking aluminum is a preferred metal buffer 38 because of its hermetic bonding with the silica or glass surface although gold or other suitable metals or metal alloys can be used the aluminum buffer can be about 20 microns thick or 5 microns thick or even thinner the wire lead 35 will have an electrode not shown at its distal end fig2 also shows a polymer coating 40 as an outer buffer this buffer is also added very soon after drawing and is applied after the metal buffer 38 in a continuous manner the plastic outer buffer coating 40 is biocompatible as discussed further below a further metal buffer can be added over the aluminum buffer 38 prior to addition of the plastic coating this can be a coating of gold or platinum for example both of which are biocompatible the plastic buffer 40 adds a further protective layer fig3 shows a modified fine wire pacing lead 42 which has a metal conductor 44 as a center element here the pure silica glass.