Kinetics and Chemistry of Hydrolysis of Ultrathin, Thermally Grown Layers of Silicon Oxide as Biofluid Barriers in Flexible Electronic Systems

Yoon Kyeung Lee, Ki Jun Yu, Yerim Kim, Younghee Yoon, Zhaoqian Xie, Enming Song, Haiwen Luan, Xue Feng, Yonggang Huang, John A. Rogers*

*Corresponding author for this work

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Flexible electronic systems for bioimplants that offer long-term (multidecade) stability and safety in operation require thin, biocompatible layers that can prevent biofluid penetration. Recent work shows that ultrathin films of silicon dioxide thermally grown (TG-SiO2) on device-grade silicon wafers and then released as transferrable barriers offer a remarkable set of attributes in this context. This paper examines the chemical stability of these materials in aqueous solutions with different combinations of chemistries that are present in biofluids. Systematic measurements reveal the dependence of the dissolution rate of TG-SiO2 on concentrations of cations (Na+, K+, Mg2+, Ca2+) and anions (Cl-, HPO42-) at near-neutral pH. Certain results are consistent with previous studies on bulk samples of quartz and nanoparticles of amorphous silica; others reveal significant catalyzing effects associated with divalent cations at high pH and with specific anions at high ionic strength. In particular, Ca2+ and HPO42- greatly enhance and silicic acid greatly reduces the rates. These findings establish foundational data of relevance to predicting lifetimes of implantable devices that use TG-SiO2 as biofluid barriers, and of other classes of systems, such as environmental monitors, where encapsulation against water penetration is important.

Original languageEnglish (US)
Pages (from-to)42633-42638
Number of pages6
JournalACS Applied Materials and Interfaces
Volume9
Issue number49
DOIs
StatePublished - Dec 13 2017

Keywords

  • encapsulation
  • flexible electronics
  • silica dissolution
  • thermal oxide
  • water barrier

ASJC Scopus subject areas

  • Materials Science(all)

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