Self-healing materials are indispensable for soft actuators and robots that operate in dynamic and real-world environments, as these machines are vulnerable to mechanical damage. However, current self-healing materials have shortcomings that limit their practical application, such as low healing strength (below a megapascal) and long healing times (hours). Here, we introduce high-strength synthetic proteins that self-heal micro- and macro-scale mechanical damage within a second by local heating. These materials are optimized systematically to improve their hydrogen-bonded nanostructure and network morphology, with programmable healing properties (2–23 MPa strength after 1 s of healing) that surpass by several orders of magnitude those of other natural and synthetic soft materials. Such healing performance creates new opportunities for bioinspired materials design, and addresses current limitations in self-healing materials for soft robotics and personal protective equipment.
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The authors thank H. Shahsavan and P. Cabanach for helpful discussions. M.C.D. and H.J. thank staff members of Penn State MRI and Huck user facilities. A.P.-F. and M.S. were supported by the Max Planck Society. A.P.-F. was also funded by the Alexander von Humboldt Foundation and the German Federal Ministry for Education and Research. M.S. was also funded by the European Research Council (ERC) Advanced Grant SoMMoR project with grant no: 834531. M.C.D. and H.J. were supported by the United States Army Research Office (grant no. W911NF-16-1-0019 and W911NF-18-1-026) and the Huck Endowment of The Pennsylvania State University.
A.P.-F. and M.C.D. have issued patents (US patent 9,663,658 and US patent 10,253,144), and H.J. and M.C.D. have issued patents (US patent 9,765,121, US patent 10,047,127, and US patent 10,246,493) on technology related to processes described in this article. All other authors have no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Note 1, Supplementary Figs. 1–20, Supplementary Videos 1–5, and Supplementary References
Heat-assisted healing of TRn11 proteins
Protein-based pneumatic soft actuator
Protein-based soft gripper
Protein-based artificial muscle
Degradation of protein-based actuators
Self-healing performance benchmark
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Pena-Francesch, A., Jung, H., Demirel, M.C. et al. Biosynthetic self-healing materials for soft machines. Nat. Mater. (2020). https://doi.org/10.1038/s41563-020-0736-2