Long-term hermeticity and biological performance of anodically bonded glass-silicon implantable packages

This paper reviews long-term test results obtained from a series of tests on glass-silicon (Si) hermetically sealed packages. Results are presented from 1) a 9.9-year ongoing room temperature phosphate-buffered saline (PBS) soak test of four packages; 2) accelerated soak tests in high temperature saline of 28 samples resulting in an extrapolated mean-time-to-failure (MTTF) at 37 degrees C of 177 years; 3) a 2.7-year in vitro 97 degrees C PBS soak test of a single package; and 4) in situ hermeticity and biocompatibility tests from 12 packages implanted in four guinea pigs-three packages implanted in two guinea pigs (each) for 1 month and another two guinea pigs for 20 and 22 months. All of the packages remained hermetically sealed over the lifetime of the implant. A detailed histological report of the implants is provided suggesting that they elicit no profound adverse reaction from the body.