Letter

An electric-eel-inspired soft power source from stacked hydrogels

  • Nature volume 552, pages 214218 (14 December 2017)
  • doi:10.1038/nature24670
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Abstract

Progress towards the integration of technology into living organisms requires electrical power sources that are biocompatible, mechanically flexible, and able to harness the chemical energy available inside biological systems. Conventional batteries were not designed with these criteria in mind. The electric organ of the knifefish Electrophorus electricus (commonly known as the electric eel) is, however, an example of an electrical power source that operates within biological constraints while featuring power characteristics that include peak potential differences of 600 volts and currents of 1 ampere1,2. Here we introduce an electric-eel-inspired power concept that uses gradients of ions between miniature polyacrylamide hydrogel compartments bounded by a repeating sequence of cation- and anion-selective hydrogel membranes. The system uses a scalable stacking or folding geometry that generates 110 volts at open circuit or 27 milliwatts per square metre per gel cell upon simultaneous, self-registered mechanical contact activation of thousands of gel compartments in series while circumventing power dissipation before contact. Unlike typical batteries, these systems are soft, flexible, transparent, and potentially biocompatible. These characteristics suggest that artificial electric organs could be used to power next-generation implant materials such as pacemakers, implantable sensors, or prosthetic devices in hybrids of living and non-living systems3,4,5,6.

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Acknowledgements

We are grateful to B. Rothen-Rutishauser and A. Petri-Fink at the Adolphe Merkle Institute for the use of their 3DDiscovery printer. F. Bircher’s iPrint institute at the Haute École d’Ingénierie et d’Architecture Fribourg, particularly F. Bourguet and M. Soutrenon, donated time towards adapting a printer for our use and helped us to understand the intricacies of microvalve printing systems. Laser cutting was performed at Fablab Fribourg. U. Steiner’s group, in particular P. Sutton and M. Fischer, provided instrumentation and advice related to impedance measurements. Research reported in this publication was supported by the Air Force Office of Scientific Research (grant FA9550-12-1-0435 to M.M., J.Y., D.S. and M.S.) and the National Institute of General Medical Sciences of the National Institutes of Health under award T32GM008353, which funds the Cellular Biotechnology Training Program (T.B.H.S.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Author information

Author notes

    • Thomas B. H. Schroeder
    •  & Anirvan Guha

    These authors contributed equally to this work.

Affiliations

  1. Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan, USA

    • Thomas B. H. Schroeder
  2. Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland

    • Thomas B. H. Schroeder
    • , Anirvan Guha
    •  & Michael Mayer
  3. Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan, USA

    • Aaron Lamoureux
    • , Gloria VanRenterghem
    •  & Max Shtein
  4. Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.

    • David Sept
    •  & Michael Mayer
  5. Center for Computational Medicine and Biology, University of Michigan, Ann Arbor, Michigan, USA

    • David Sept
  6. Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, USA

    • Jerry Yang

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Contributions

T.B.H.S., A.G., J.Y. and M.M. conceived the project and designed the experiments. T.B.H.S. and A.G. performed all data collection. A.L. and M.S. provided the idea of Miura-ori folding. G.V. helped to define the parameters of the fluidic implementation. T.B.H.S. and D.S. conducted analysis of literature electrical datasets of Electrophorus. T.B.H.S., A.G. and M.M. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Michael Mayer.

Reviewer Information Nature thanks C. Bettinger, P. Calvert and A. Stokes for their contribution to the peer review of this work.

Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    This file contains seven discussion sections and two supplementary tables. The contents are theoretical background, characterization, fabrication methods, and calculations related to the artificial electric organ presented in this work.

Videos

  1. 1.

    Fluidic artificial organ implementation

    This video shows fluidic artificial organ implementation.

  2. 2.

    Printer depositing gels for serpentine implementation.

    This video shows printer depositing gels for serpentine implementation.

  3. 3.

    Miura-ori folding of a gel-bearing substrate

    This video shows Miura-ori folding of a gel-bearing substrate.

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