Accelerated, Reactive Aging Tests of Parylene C, SiO 2 , and Si 3 N 4 Packages for Chronic Neural Implants

Reliable packaging for implantable neural prosthetic devices in body fluids is a long-standing challenge for device’s chronic applications. This work studied the stability of Parylene C (PA), SiO 2 , and Si 3 N 4 packages on tungsten wires using accelerated, reactive aging tests in three solutions: pH 7.4 phosphate-buffered saline (PBS), PBS+30 mM H 2 O 2 , and PBS+150 mM H 2 O 2 . Different combinations of coating thicknesses and deposition methods were studied at 67 °C. Analysis of the preliminary data shows that the pinholes/defects, cracks, and interface delamination are the main attributes of metal erosion and degradation in reactive aging solutions. Failure at the interface of package and metal is the dominating factor in the wire samples with open tips.