Long term glass-encapsulated packaging for implant electronics

Hermetic Titanium-alloy packaging (e.g., used in pacemakers and cochlear implants) has been accepted as the industrial standard for decades. However, two remaining issues of this well-known technology are the size and limited number of feedthroughs [1]. On the other hand, the next generation wireless intraocular retinal prosthetic devices do require unprecedented small size and large number of leads to be fitted inside a human eyeball so the traditional metal packaging is difficult to be implemented. Therefore, these new generation of microimplants will need a new packaging scheme. This paper then reports a new long-term packaging method using glass encapsulation featuring a controlled failure mode from fast diffusion to slow undercut. The results is promising that this new packaging scheme could survive more than 10 years by accelerated "active" lifetime soaking test (i.e., with electric field applied) in 0.9 wt.% saline solution. As a whole, this new method provides several advantages including easy employment, controllable long life time, and enhanced heat dissipation.