Failure mode analysis of al2O2-parylene c bilayer encapsulation for implantable devices and application to penetrating neural arrays

We assess the performance of a parylene C - aluminum oxide bilayer encapsulation strategy as it applies to implantable devices with non-planar topography. Electrochemical measurements of devices subject to in vitro accelerated lifetime testing are analyzed to evaluate benefits of bilayer encapsulation versus parylene C alone. Failure modes associated with device features and topographies are identified and solutions are presented that promote stability of device impedances.