A perfectly sealed noble metal surface is a necessity for systems used to identify pathogens.
Traditional surfaces for diagnostic devices were built over nickel and similar metals. These interfered with some analytical techniques, however. One answer was a noble metal, gold.
Gold is widely used in biomedical diagnostics, particularly in the sensors and circuit boards that are the heart of all electronics. Gold is, however, inherently porous. As a result, it is imperfect at best for advanced spectroscopy and other emerging techniques.
To achieve zero porosity, zero contamination and a sealed, contaminant-free surface, a metallic layer stack comprised of palladium with fine-grained gold overplate has proved optimum.
There are two processes, both developed and patented by Uyemura, that are exquisitely suited to spectroscopic and other advanced diagnostics. They are EPIG (electroless palladium / immersion gold) and EPAG (electroless palladium/ autocatalytic gold).
In both, the palladium layer is Uyemura Talon; the gold layer is Uyemura TWX-42. The EPIG process allows gold to build predictably and with exceptional uniformity up to 8 μin.
The processes are economical, and compatible with existing equipment; there is no free cyanide involved and no elaborate lab analysis needed.