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Stretchable, Multiplexed pH Sensors With Demonstrations on Rabbit and Human Hearts Undergoing Ischemia

Authors

  • Hyun-Joong Chung,

    1. Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 2V4, Canada
    2. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
    Current affiliation:
    1. These authors contributed equally to this work.
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  • Matthew S. Sulkin,

    1. Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO, USA
    Current affiliation:
    1. These authors contributed equally to this work.
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  • Jong-Seon Kim,

    1. Department of Chemical and Biomolecular, Engineering (BK21 Program), Korea Advanced Institute of Science and Technology, Daejeon, Korea
    Current affiliation:
    1. These authors contributed equally to this work.
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  • Camille Goudeseune,

    1. Illinois Simulator Laboratory, Beckman Institute, University of Illinois, Urbana, IL 61801, USA
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  • Hsin-Yun Chao,

    1. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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  • Joseph W. Song,

    1. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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  • Sang Yoon Yang,

    1. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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  • Yung-Yu Hsu,

    1. MC10 Inc. 36 Cameron Avenue, Cambridge, MA 02140, USA
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  • Roozbeh Ghaffari,

    1. MC10 Inc. 36 Cameron Avenue, Cambridge, MA 02140, USA
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  • Igor R. Efimov,

    Corresponding author
    1. Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO, USA
    • Igor R. Efimov, Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO, USA

      John A. Rogers, Department of Materials Science and Engineering, Chemistry, Mechanical Science and Engineering, Electrical, and Computer Engineering, Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

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  • John A. Rogers

    Corresponding author
    1. Department of Materials Science and Engineering, Chemistry, Mechanical Science and Engineering, Electrical, and Computer Engineering, Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
    • Igor R. Efimov, Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO, USA

      John A. Rogers, Department of Materials Science and Engineering, Chemistry, Mechanical Science and Engineering, Electrical, and Computer Engineering, Beckman Institute for Advanced Science and Technology and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

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Abstract

Stable pH is an established biomarker of health, relevant to all tissues of the body, including the heart. Clinical monitoring of pH in a practical manner, with high spatiotemporal resolution, is particularly difficult in organs such as the heart due to its soft mechanics, curvilinear geometry, heterogeneous surfaces, and continuous, complex rhythmic motion. The results presented here illustrate that advanced strategies in materials assembly and electrochemical growth can yield interconnected arrays of miniaturized IrOx pH sensors encapsulated in thin, low-modulus elastomers to yield conformal monitoring systems capable of noninvasive measurements on the surface of the beating heart. A thirty channel custom data acquisition system enables spatiotemporal pH mapping with a single potentiostat. In vitro testing reveals super-Nernstian sensitivity with excellent uniformity (69.9 ± 2.2 mV/pH), linear response to temperature (−1.6 mV °C−1), and minimal influence of extracellular ions (<3.5 mV). Device examples include sensor arrays on balloon catheters and on skin-like stretchable membranes. Real-time measurement of pH on the surfaces of explanted rabbit hearts and a donated human heart during protocols of ischemia–reperfusion illustrate some of the capabilities. Envisioned applications range from devices for biological research, to surgical tools and long-term implants.

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