An implantable medical system includes a first die substrate with a first outer surface. The system also includes a second die substrate with a second outer surface. Furthermore, the system includes a medical device with a first portion that is mounted to the first die substrate and a second portion that is mounted to the second die substrate. The first and second die substrates are fixed to each other and substantially hermetically sealed to each other. Also, the medical device is substantially encapsulated between the first and second die substrates. The first portion is electrically connected to the second portion. Moreover, the first and second outer surfaces of the first and second die substrates are directly exposed to a biological material.