Ultrathin, transferred layers of thermally grown silicon dioxide as biofluid barriers for biointegrated flexible electronic systems.

TitleUltrathin, transferred layers of thermally grown silicon dioxide as biofluid barriers for biointegrated flexible electronic systems.
Publication TypeJournal Article
Year of Publication2016
AuthorsH Fang, J Zhao, KJ Yu, E Song, AB Farimani, C-H Chiang, X Jin, Y Xue, D Xu, W Du, KJ Seo, Y Zhong, Z Yang, SM Won, G Fang, SW Choi, S Chaudhuri, Y Huang, MA Alam, J Viventi, NR Aluru, and JA Rogers
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue42
Start Page11682
Pagination11682 - 11687
Date Published10/2016
Abstract

Materials that can serve as long-lived barriers to biofluids are essential to the development of any type of chronic electronic implant. Devices such as cardiac pacemakers and cochlear implants use bulk metal or ceramic packages as hermetic enclosures for the electronics. Emerging classes of flexible, biointegrated electronic systems demand similar levels of isolation from biofluids but with thin, compliant films that can simultaneously serve as biointerfaces for sensing and/or actuation while in contact with the soft, curved, and moving surfaces of target organs. This paper introduces a solution to this materials challenge that combines (i) ultrathin, pristine layers of silicon dioxide (SiO2) thermally grown on device-grade silicon wafers, and (ii) processing schemes that allow integration of these materials onto flexible electronic platforms. Accelerated lifetime tests suggest robust barrier characteristics on timescales that approach 70 y, in layers that are sufficiently thin (less than 1 μm) to avoid significant compromises in mechanical flexibility or in electrical interface fidelity. Detailed studies of temperature- and thickness-dependent electrical and physical properties reveal the key characteristics. Molecular simulations highlight essential aspects of the chemistry that governs interactions between the SiO2 and surrounding water. Examples of use with passive and active components in high-performance flexible electronic devices suggest broad utility in advanced chronic implants.

DOI10.1073/pnas.1605269113
Short TitleProceedings of the National Academy of Sciences of the United States of America