Preventing saline moisture penetration into high-voltage intracranial electronics.
Radio transparency requires non-metallic windows. High-purity monocrystalline sapphire disks are vacuum-brazed to titanium rings using gold-nickel alloys, passing helium leak tests below 1e-9 atm*cc/s.
Capacitive moisture sensors inside the vacuum cavity monitor moisture ingress over years, alerting clinical teams before corrosion can cause circuit malfunctions.