A Chip Integrity Monitor for Evaluating Long-term Encapsulation Performance Within Active Flexible Implants

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 um 6-metal CMOS process. For chip validation, dry and wet measurements in saline are presented in this paper.

Published in Proceedings of IEEE Biomedical Circuis and Systems Conference (BioCAS) 2019

DOI: https://doi.org/10.1109/BIOCAS.2019.8919203

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 author = {Akgun, O. C. and Nanbakhsh, K. and Giagka, V. and Serdijn, W. A.},
 booktitle = {Proceedings of IEEE Biomedical Circuits and Systems (BioCAS)},
 title = {{"A Chip Integrity Monitor Platform for Evaluating Long-term
 Encapsulation Performance Within Active Flexible Implants"}},
 month = {Oct}, 
 year = {2019},
 pages = {1-5},