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.
|Number of pages||6|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 2016 Oct 18|
Bibliographical noteFunding Information:
We acknowledge the Micro and Nanotechnology Laboratory for device fabrication and the Beckman Institute for Advanced Science and Technology for device measurement. This work was supported by Defense Advanced Research Projects Agency Contract HR0011-14-C-0102, National Science Foundation Award 1403582, National Science Foundation Award CCF-1422914, and Army Research Office Award W911NF-14-1-0173, and performed in the Frederick Seitz Materials Research Laboratory and the Center for Microanalysis of Materials at the University of Illinois at Urbana-Champaign. J.Z. acknowledges supports from Louis J. Larson Fellowship, Swiegert Fellowship, and H. C. Ting Fellowship from the University of Illinois at Urbana-Champaign. E.S. acknowledges support from China Scholarship Council.
© 2016, National Academy of Sciences. All rights reserved.
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