Reliable packaging for parylene-based flexible retinal implant

MEMS technology has been used more and more in biomedical application for neural prosthetic implantation [1, 2]. These devices, however, will have to endure harsh and corrosive body fluids [3]. Therefore, biostable and hermetic-like packaging is needed to protect the implant. This work reports the package reliability of parylene-based retinal implant using active (i.e., with electrical signals applied) and accelerated lifetime soaking test in saline. Commercial amplifier chips, dummy conduction chips, and discrete components are tested and the failure modes are examined. It is found that the proposed parylene-metal-parylene flexible composite sandwich layers indeed have longer lifetime than traditional inflexible silicone-parylene combination. In addition, the chip size effect on lifetime is observed that smaller chips have longer lifetime under the same protection.