Transferred, Ultrathin Oxide Bilayers as Biofluid Barriers for Flexible Electronic Implants
Abstract
The work presented here introduces a materials strategy that involves physically transferred, ultrathin layers of silicon dioxide (SiO2) thermally grown on silicon wafers and then coated with hafnium oxide (HfO2) by atomic layer deposition, as barriers that satisfy requirements for even the most challenging flexible electronic devices. Materials and physics aspects of hydrolysis and ionic transport associated with such bilayers define their performance and reliability characteristics. Systematic experimental studies and reactive diffusion modeling suggest that the HfO2 film, even with some density of pinholes, slows dissolution of the underlying SiO2 by orders of magnitude, independent of the concentration of ions in the surrounding biofluids. Accelerated tests that involve immersion in phosphate‐buffered saline solution at a pH of 7.4 and under a constant electrical bias demonstrate that this bilayer barrier can also obstruct the transport of ions that would otherwise cause drifts in the operation of the electronics. Theoretical drift–diffusion modeling defines the coupling of dissolution and ion diffusion, including their effects on device lifetime. Demonstrations of such barriers with passive and active components in thin, flexible electronic test structures highlight the potential advantages for wide applications in chronic biointegrated devices.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 20, 2017
- Source ID
- 10.1002/adfm.201702284
Entities
People
- Enming Song
- Guanhua Fang
- Haina Du
- Hui Fang
- Jinghua Li
- Jize Zhang
- John A. Rogers
- Ki Jun Yu
- Muhammad Ashraful Alam
- Rui Li
- Xin Jin
- Yerim Kim
- Yiding Zhong
- Yongfeng Mei
- Yonggang Huang
- Yoon Kyeung Lee
- Younghee Yoon
- Zhaoqian Xie
Organizations
- China Scholarship Council
- Defense Advanced Research Projects Agency
- Fudan University
- National Institutes of Health
- National Natural Science Foundation of China
- National Science Foundation
- Northeastern University
- Northwestern University
- Purdue University
- University of Illinois Urbana–Champaign
- Yonsei University