Micrometer-sized electrically programmable shape-memory actuators for low-power microrobotics.

Journal: Science robotics
Published Date: Mar 17, 2021

Abstract

Shape-memory actuators allow machines ranging from robots to medical implants to hold their form without continuous power, a feature especially advantageous for situations where these devices are untethered and power is limited. Although previous work has demonstrated shape-memory actuators using polymers, alloys, and ceramics, the need for micrometer-scale electro-shape-memory actuators remains largely unmet, especially ones that can be driven by standard electronics (~1 volt). Here, we report on a new class of fast, high-curvature, low-voltage, reconfigurable, micrometer-scale shape-memory actuators. They function by the electrochemical oxidation/reduction of a platinum surface, creating a strain in the oxidized layer that causes bending. They bend to the smallest radius of curvature of any electrically controlled microactuator (~500 nanometers), are fast (<100-millisecond operation), and operate inside the electrochemical window of water, avoiding bubble generation associated with oxygen evolution. We demonstrate that these shape-memory actuators can be used to create basic electrically reconfigurable microscale robot elements including actuating surfaces, origami-based three-dimensional shapes, morphing metamaterials, and mechanical memory elements. Our shape-memory actuators have the potential to enable the realization of adaptive microscale structures, bio-implantable devices, and microscopic robots.

Authors

  • Qingkun Liu
    Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA. ql59@cornell.edu plm23@cornell.edu itai.cohen@cornell.edu.
  • Wei Wang
    State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau 999078, China.
  • Michael F Reynolds
    Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA.
  • Michael C Cao
    School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.
  • Marc Z Miskin
    Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, USA.
  • Tomas A Arias
    Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA.
  • David A Muller
    School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.
  • Paul L McEuen
    Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA. ql59@cornell.edu plm23@cornell.edu itai.cohen@cornell.edu.
  • Itai Cohen
    Laboratory of Atomic and Solid-State Physics, Cornell University, Ithaca, NY 14853, USA. ql59@cornell.edu plm23@cornell.edu itai.cohen@cornell.edu.

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