Automated and Wireless Accelerated Heat Soak Testing System to Assess Hermetic Failure Mechanism of Inductively Powered Implantable Medical Applications

Reliability and lifetime estimation of implantable medical devices (IMDs) is one of the essential steps in their design and development. As any failure of IMDs can result in serious health risks for the patients, they should be guaranteed not to fail over their intended lifetime under the harsh body fluidic and chemical environments. Traditional leak tests are applicable to large cm-scale IMDs, and they are often destructive, laborious, and costly. This paper presents an automated and wireless accelerated heat soak testing system to assess hermetic failure mechanisms in small mm-sized inductively powered IMDs. A high-throughput readout coil array printed circuit board can test hermeticity of multiple mm-sized wireless IMDs simultaneously in a harsh environment (e.g., 45 degrees C/90% RH with an error range of +/- 0.2% for 18 days gage repeatability and reproducibility test). An accelerated heat soak test is performed to evaluate the electronic durability and estimate the lifetime of the IMDs. This work focuses on validating the proposed system interrogating with eight inductor-capacitor sensors, composed of an interdigitated capacitive sensor connected to an inductor patterned polyimide substrate, to examine hermetic failure mechanisms of parylene-C encapsulation for wireless IMDs as well as broader miniature-sized consumer electronics.