Biomedical implants that incorporate active electronics and offer the ability to operate in a safe, stable fashion for long periods of time must incorporate defect-free layers as barriers to biofluid penetration. This paper reports an engineered material approach to this challenge that combines ultrathin, physically transferred films of silicon dioxide (t-SiO2) thermally grown on silicon wafers, with layers of hafnium oxide (HfO2) formed by atomic layer deposition and coatings of parylene (Parylene C) created by chemical vapor deposition, as a dual-sided encapsulation structure for flexible bioelectronic systems. Accelerated aging tests on passive/active components in platforms that incorporate active, silicon-based transistors suggest that this trilayer construct can serve as a robust, long-lived, defect-free barrier to phosphate-buffered saline (PBS) solution at a physiological pH of 7.4. Reactive diffusion modeling and systematic immersion experiments highlight fundamental aspects of water diffusion and hydrolysis behaviors, with results that suggest lifetimes of many decades at physiological conditions. A combination of ion-diffusion tests under continuous electrical bias, measurements of elemental concentration profiles, and temperature-dependent simulations reveals that this encapsulation strategy can also block transport of ions that would otherwise degrade the performance of the underlying electronics. These findings suggest broad utility of this trilayer assembly as a reliable encapsulation strategy for the most demanding applications in chronic biomedical implants and high-performance flexible bioelectronic systems.
|Number of pages||10|
|Publication status||Published - 2018|
Bibliographical noteFunding Information:
This work was supported by Defense Advanced Research Projects Agency Contract HR0011-14-C-0102, and the Center for Bio-Integrated Electronics. We acknowledge the use of facilities in the Micro and Nanotechnology Laboratory for device fabrication and the Frederick Seitz Materials Research Laboratory for Advanced Science and Technology for device measurement at the University of Illinois at Urbana- Champaign. R.L. acknowledges the support from the Young Elite Scientists Sponsorship Program by CAST (No. 2015QNRC001) and Opening Fund of State Key Laboratory of Nonlinear Mechanics, Chinese Academy of Sciences. X.J. And M.A.A. acknowledge the support from Lilly Endowment through the Wabash Heartland Innovation Network (WHIN) (grant number: 40001922). K.J.Y. acknowledges the support from the National Research Foundation of Korea (NRF-2017M1A2A2048880, NRF-2018M3A7B4071109) and the Yonsei University Future-leading Research Initiative of (RMS2 2018-22-0028).
© 2018 American Chemical Society
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physics and Astronomy(all)