
(c)2026 David Prutchi PhD
In the 1960s and early 1970s, pacemakers powered by mercury/zinc cells had to be enclosed in epoxy because the cells produced hydrogen, which could safely diffuse outward through the epoxy’s permeability to hydrogen.
However, epoxy encapsulation also allowed water molecules to penetrate into the battery area and electronic assembly, often causing their failure.
In 1971, Australian pacemaker company Telectronics produced the model P8; the first hermetically sealed pulse generator in a titanium case. The hydrogen problem was taken care of by means of a
hydrogen absorbent inside the case, and the high welding temperature needed to seal the case, without damaging the contents, by a carefully worked out combination of fast welding and external heat sinking and cooling.
The P10 model shown here was based on the P8, but incorporated a silicone elastomer coating to limit the area of the indifferent electrode to prevent pectoral muscle stimulation.















