A Chip Integrity Monitor for Evaluating Long-term Encapsulation Performance Within Active Flexible Implants
O.C. Akgün (TU Delft - Bio-Electronics)
Kambiz Nanbakhsh (TU Delft - Bio-Electronics)
V. Giagka (TU Delft - Bio-Electronics, Fraunhofer Institute for Reliability and Microintegration IZM)
W.A. Serdijn (TU Delft - Bio-Electronics)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
One key obstacle in employing silicon integrated circuits in flexible implants is ensuring a long-term operation of the chip within the wet corrosive environment of the body. For this reason, throughout the years, various biocompatible insulating materials have been proposed, yet, evaluating their long-term encapsulation performance on representative silicon samples still remains to be the main challenge. For this aim, in this work, a sensitive platform is introduced that can track the integrity of the chip against water and ion ingress. This platform is developed to be used for long-term monitoring of chip integrity and study of encapsulation layers in wet environments. The platform comprises a sensing array and a measurement engine and operates by tracking the changes in the inter-layer dielectric resistance within the chip. The proposed system uses a novel charge/discharge-based time-mode resistance sensor that can be implemented using simple yet highly robust circuitry. The sensor array is implemented together with the measurement engine in a standard 0.18 µm 6-metal CMOS process. For chip validation, dry and wet measurements in saline are presented in this paper.