Reliability of Implantable Electronic Devices: Two Case Studies

This paper presents two case studies of the reliability of implantable neural stimulators, designed specifically as auditory prostheses. These reliability results, collected from lifetime experiments, failure analysis, and manufacturing testing, confirm the crucial roles of well planned design and packaging in system reliability. Guidelines are proposed for the design of reliable implantable systems. The improvements in the second design can be traced to the better electronic design and manufacture, the careful considerations of metallurgical characteristics in bonding and connecting components, the package design, and the exhaustive tests at each step of the manufacturing process. The reliability of these designs, and of implantable systems in general, is by no means resolved nor well understood. There is a definite need for comprehensive data bases and techniques for reliability analysis of these systems as well as the systematic manufacturing test for reliability assurance, which is a growing concern in the research and development of artificial organs.