Peterson Type Barbed Electrode
The electrode is shown partially loaded into a hypodermic needle, on the left hand side of the figure. The diameter of the wound-insulated portion is approximately 800 µm. The materials used in the fabrication of these electrodes are:
316 LVM stainless steel wire forms the conducting lead and the stimulating tip. The wire is stranded from seven strands of wire each strand is 40 µm in diameter. Perfluoroalkoxy (PFA) insulation 50 to 75 µm in thickness. Polypropylene suture material, 5-0 gage or diameter, forms the barb and center core of the electrode assembly.

The subcutaneous tissue reaction to the Peterson type of electrode is shown in Figure. The tissue was cut in a plane that is parallel to the axis of the electrode. In the left hand panel, the area appearing as an oval hole is the space occupied by the insulated helix portion of the electrode lead. The long oval space in between the oval holes is the space occupied by the polypropylene core. In the right hand panel is the tissue reaction around the stimulating tip/barb portion of the electrode. High power magnification of the tissue encapsulation between two windings of the helically wound lead of the Peterson electrode. At the interface between the electrode insulation and the tissue a compact group of cells forms a barrier between the implant and the interstitial space, indicated by arrows. This barrier layer is in the range of three to four cell layers thick. The space between the barrier walls contains a loose connection of cells and collagen.

Corey, J. M. (1990) Tissue Response and Corrosion Studies of the Peterson Type Intramuscular Electrode, Master of Science, Case Western Reserve University.