Self-Healing E‑tongue

Anerise de Barros, Gabriel Gaál, Maria L. Braunger, Mawin J. Martinez Jimenez, Carlos Avila-Avendano, Varlei Rodrigues, Mônica Jung de Andrade, Manuel Quevedo-Lopez, Fernando Alvarez, Ray H. Baughman, Antonio Riul*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Self-healing materials inspire the next generation of multifunctional wearables and Internet of Things appliances. They expand the realm of thin film fabrication, enabling seamless conformational coverage irrespective of the shape complexity and surface geometry for electronic skins, smart textiles, soft robotics, and energy storage devices. Within this context, the layer-by-layer (LbL) technique is versatile for homogeneously dispersing materials onto various matrices. Moreover, it provides molecular level thickness control and coverage on practically any surface, with poly(ethylenimine) (PEI) and poly(acrylic acid) (PAA) being the most used materials primarily employed in self-healing LbL structures operating at room temperature. However, achieving thin film composites displaying controlled conductivity and healing ability is still challenging under ambient conditions. Here, PEI and PAA are mixed with conductive fillers (gold nanorods, poly(3,4-ethylene dioxythiophene): polystyrenesulfonate (PEDOT:PSS), reduced graphene oxides, and multiwalled carbon nanotubes) in distinct LbL film architectures. Electrical (AC and DC), optical (Raman spectroscopy), and mechanical (nanoindentation) measurements are used for characterizing composite structures and properties. A delicate balance among electrical, mechanical, and structural characteristics must be accomplished for a controlled design of conductive self-healing composites. As a proof-of-concept, four LbL composites were chosen as sensing units in the first reported self-healing e-tongue. The sensor can easily distinguish basic tastes at low molar concentrations and differentiate trace levels of glucose in artificial sweat. The formed nanostructures enable smart coverages that have unique features for solving current technological challenges.

Original languageEnglish
Pages (from-to)55073-55081
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number47
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 American Chemical Society.


  • Electronic tongue
  • impedimetric
  • self-healing
  • sweat
  • tastants


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