Soft Elastomers with Ionic Liquid-Filled Cavities as Strain Isolating Substrates for Wearable Electronics

Yinji Ma, Matt Pharr, Liang Wang, Jeonghyun Kim, Yuhao Liu, Yeguang Xue, Rui Ning, Xiufeng Wang, Ha Uk Chung, Xue Feng, John A. Rogers*, Yonggang Huang

*Corresponding author for this work

Research output: Contribution to journalArticle

50 Scopus citations

Abstract

Managing the mechanical mismatch between hard semiconductor components and soft biological tissues represents a key challenge in the development of advanced forms of wearable electronic devices. An ultralow modulus material or a liquid that surrounds the electronics and resides in a thin elastomeric shell provides a strain-isolation effect that enhances not only the wearability but also the range of stretchability in suitably designed devices. The results presented here build on these concepts by (1) replacing traditional liquids explored in the past, which have some nonnegligible vapor pressure and finite permeability through the encapsulating elastomers, with ionic liquids to eliminate any possibility for leakage or evaporation, and (2) positioning the liquid between the electronics and the skin, within an enclosed, elastomeric microfluidic space, but not in direct contact with the active elements of the system, to avoid any negative consequences on electronic performance. Combined experimental and theoretical results establish the strain-isolating effects of this system, and the considerations that dictate mechanical collapse of the fluid-filled cavity. Examples in skin-mounted wearable include wireless sensors for measuring temperature and wired systems for recording mechano-acoustic responses.

Original languageEnglish (US)
Article number1602954
JournalSmall
Volume13
Issue number9
DOIs
StatePublished - Mar 7 2017

Keywords

  • flexible electronics
  • ionic liquid
  • stretchable electronics
  • wearable electronics

ASJC Scopus subject areas

  • Biotechnology
  • Biomaterials
  • Chemistry(all)
  • Materials Science(all)

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