According to this technique of packaging a sensor device implantable in a living body so as to provide protection of the sensor device and to the living body itself, an electrical conductor of the sensor device is sealed in an insulating substrate extending between proximal and distal ends. The distal end of the electrical conductor is externally connected to an external sensor on the sensor device and the proximal end of the electrical conductor is externally connected to a distal end of a lead wire extending proximally to a pulse generator and these connections are embedded in an insulative sheath. The external sensor, substrate, and insulative sheath are encapsulated in a thin film of hermetic material without interference with the lead wire. In another embodiment, a layer of insulating material may underlie the hermetic material to encapsulate the external sensor and the substrate.