Biosynthetic self-healing materials for soft machines


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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Fig. 1: Cephalopod-inspired biosynthetic proteins.
Fig. 2: Self-healing polypeptides.
Fig. 3: Self-healing of extreme mechanical damage.
Fig. 4: Self-healing, protein-based soft actuator.

Data availability

All relevant data that support the findings of this study are available in the article and its supplementary files. Source data for Figs. 1b,1c,4c are available in the Source Data files. Additional data can be obtained from the authors upon request.


  1. 1.

    Rus, D. & Tolley, M. T. Design, fabrication and control of soft robots. Nature 521, 467–475 (2015).

    CAS  Google Scholar 

  2. 2.

    Hu, W., Lum, G. Z., Mastrangeli, M. & Sitti, M. Small-scale soft-bodied robot with multimodal locomotion. Nature 554, 81–85 (2018).

    CAS  Google Scholar 

  3. 3.

    Ren, Z., Hu, W., Dong, X. & Sitti, M. Multi-functional soft-bodied jellyfish-like swimming. Nat. Commun. 10, 2703 (2019).

    Google Scholar 

  4. 4.

    Martinez, R. V., Glavan, A. C., Keplinger, C., Oyetibo, A. I. & Whitesides, G. M. Soft actuators and robots that are resistant to mechanical damage. Adv. Funct. Mater. 24, 3003–3010 (2014).

    CAS  Google Scholar 

  5. 5.

    Yang, G.-Z. et al. The grand challenges of Science Robotics. Sci. Robot. 3, eaar7650 (2018).

    Google Scholar 

  6. 6.

    Blaiszik, B. J. et al. Self-healing polymers and composites. Annu. Rev. Mater. Res. 40, 179–211 (2010).

    CAS  Google Scholar 

  7. 7.

    Terryn, S., Brancart, J., Lefeber, D., van Assche, G. & Vanderborght, B. Self-healing soft pneumatic robots. Sci. Robot. 2, eaan4268 (2017).

    Google Scholar 

  8. 8.

    Canadell, J., Goossens, H. & Klumperman, B. Self-healing materials based on disulfide links. Macromolecules 44, 2536–2541 (2011).

    CAS  Google Scholar 

  9. 9.

    Cordier, P., Tournilhac, F., Soulié-Ziakovic, C. & Leibler, L. Self-healing and thermoreversible rubber from supramolecular assembly. Nature 451, 977–980 (2008).

    CAS  Google Scholar 

  10. 10.

    Chen, Y., Kushner, A. M., Williams, G. A. & Guan, Z. Multiphase design of autonomic self-healing thermoplastic elastomers. Nat. Chem. 4, 467–472 (2012).

    CAS  Google Scholar 

  11. 11.

    Li, C.-H. et al. A highly stretchable autonomous self-healing elastomer. Nat. Chem. 8, 618–624 (2016).

    CAS  Google Scholar 

  12. 12.

    Cao, Y. et al. A transparent, self‐healing, highly stretchable ionic conductor. Adv. Mater. 29, 1605099 (2017).

    Google Scholar 

  13. 13.

    Urban, M. W. et al. Key-and-lock commodity self-healing copolymers. Science 362, 220–225 (2018).

    CAS  Google Scholar 

  14. 14.

    Bilodeau, R. A. & Kramer, R. K. Self-healing and damage resilience for soft robotics: a review. Front. Robot. AI 4, 48 (2017).

    Google Scholar 

  15. 15.

    Acome, E. et al. Hydraulically amplified self-healing electrostatic actuators with muscle-like performance. Science 359, 61–65 (2018).

    CAS  Google Scholar 

  16. 16.

    Markvicka, E. J., Bartlett, M. D., Huang, X. & Majidi, C. An autonomously electrically self-healing liquid metal–elastomer composite for robust soft-matter robotics and electronics. Nat. Mater. 17, 618–624 (2018).

    CAS  Google Scholar 

  17. 17.

    Tan, Y. J. et al. A transparent, self-healing and high-κ dielectric for low-field-emission stretchable optoelectronics. Nat. Mater. 19, 182–188 (2020).

    CAS  Google Scholar 

  18. 18.

    Huynh, T.-P., Sonar, P. & Haick, H. Advanced materials for use in soft self‐healing devices. Adv. Mater. 29, 1604973 (2017).

    Google Scholar 

  19. 19.

    Roberts, A. D. et al. Synthetic biology for fibers, adhesives, and active camouflage materials in protection and aerospace. MRS Commun. 9, 486–504 (2019).

    CAS  Google Scholar 

  20. 20.

    Jung, H. et al. Molecular tandem repeat strategy for elucidating mechanical properties of high-strength proteins. Proc. Natl Acad. Sci. 113, 6478–6483 (2016).

    CAS  Google Scholar 

  21. 21.

    Guerette, P. A. et al. Accelerating the design of biomimetic materials by integrating RNA-seq with proteomics and materials science. Nat. Biotechnol. 31, 908–915 (2013).

    CAS  Google Scholar 

  22. 22.

    Nixon, M. & Dilly, P. N. Sucker surfaces and prey capture. Symp. Zool. Soc. Lond. 38, 447–511 (1977).

    Google Scholar 

  23. 23.

    Pena-Francesch, A. & Demirel, M. C. Squid-inspired tandem repeat proteins: functional fibers and films. Front. Chem. 7, 69 (2019).

    CAS  Google Scholar 

  24. 24.

    Pena-Francesch, A. et al. Mechanical properties of tandem-repeat proteins are governed by network defects. ACS Biomater. Sci. Eng. 4, 884–891 (2018).

    CAS  Google Scholar 

  25. 25.

    Pena-Francesch, A. et al. Programmable proton conduction in stretchable and self-healing proteins. Chem. Mater. 30, 898–905 (2018).

    CAS  Google Scholar 

  26. 26.

    Tomko, J. A. et al. Tunable thermal transport and reversible thermal conductivity switching in topologically networked bio-inspired materials. Nat. Nanotechnol. 13, 959–964 (2018).

    CAS  Google Scholar 

  27. 27.

    Zhong, M., Wang, R., Kawamoto, K., Olsen, B. D. & Johnson, J. A. Quantifying the impact of molecular defects on polymer network elasticity. Science 353, 1264–1268 (2016).

    CAS  Google Scholar 

  28. 28.

    Sariola, V. et al. Segmented molecular design of self-healing proteinaceous materials. Sci. Rep. 5, 13482 (2015).

    Google Scholar 

  29. 29.

    Ding, D. et al. From soft self‐healing gels to stiff films in suckerin‐based materials through modulation of crosslink density and β‐sheet content. Adv. Mater. 27, 3953–3961 (2015).

    CAS  Google Scholar 

  30. 30.

    Bier, J. M., Verbeek, C. J. R. & Lay, M. C. Thermal transitions and structural relaxations in protein‐based thermoplastics. Macromol. Mater. Eng. 299, 524–539 (2014).

    CAS  Google Scholar 

  31. 31.

    Cebe, P. et al. Beating the heat - fast scanning melts silk beta sheet crystals. Sci. Rep. 3, 1130 (2013).

    Google Scholar 

  32. 32.

    Cho, S. H., White, S. R. & Braun, P. V. Self‐healing polymer coatings. Adv. Mater. 21, 645–649 (2009).

    CAS  Google Scholar 

  33. 33.

    White, S. R. et al. Autonomic healing of polymer composites. Nature 409, 794–797 (2001).

    CAS  Google Scholar 

  34. 34.

    Hines, L., Petersen, K., Lum, G. Z. & Sitti, M. Soft actuators for small‐scale robotics. Adv. Mater. 29, 1603483 (2017).

    Google Scholar 

  35. 35.

    Ilievski, F., Mazzeo, A. D., Shepherd, R. F., Chen, X. & Whitesides, G. M. Soft robotics for chemists. Angew. Chem. Int. Ed. 50, 1890–1895 (2011).

    CAS  Google Scholar 

  36. 36.

    Song, S., Drotlef, D.-M., Majidi, C. & Sitti, M. Controllable load sharing for soft adhesive interfaces on three-dimensional surfaces. Proc. Natl Acad. Sci. 114, E4344–E4353 (2017).

    CAS  Google Scholar 

  37. 37.

    Josie, H. et al. Soft manipulators and grippers: a review. Front. Robot. AI 3, 69 (2016).

    Google Scholar 

  38. 38.

    Madden, J. D. W. et al. Artificial muscle technology: physical principles and naval prospects. IEEE J. Ocean. Eng. 29, 706–728 (2004).

    Google Scholar 

  39. 39.

    Miriyev, A., Stack, K. & Lipson, H. Soft material for soft actuators. Nat. Commun. 8, 596 (2017).

    Google Scholar 

  40. 40.

    Rich, S. I., Wood, R. J. & Majidi, C. Untethered soft robotics. Nat. Electron. 1, 102–112 (2018).

    Google Scholar 

  41. 41.

    Baumgartner, M. et al. Resilient yet entirely degradable gelatin-based biogels for soft robots and electronics. Nat. Mater. (2020).

  42. 42.

    Pena-Francesch, A., Giltinan, J. & Sitti, M. Multifunctional and biodegradable self-propelled protein motors. Nat. Commun. 10, 3188 (2019).

    Google Scholar 

  43. 43.

    Pena-Francesch, A. et al. Materials fabrication from native and recombinant thermoplastic squid proteins. Adv. Funct. Mater. 24, 7401–7409 (2014).

    CAS  Google Scholar 

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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.

Author information




A.P.-F., M.C.D., and M.S. conceived the project. A.P.-F. designed and performed the experiments, analysed the data, and wrote the manuscript. H.J. performed the protein expression and purification. All authors participated in manuscript revisions, discussions, and data interpretation.

Corresponding authors

Correspondence to Melik C. Demirel or Metin Sitti.

Ethics declarations

Competing interests

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.

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Supplementary information

Supplementary Information

Supplementary Note 1, Supplementary Figs. 1–20, Supplementary Videos 1–5, and Supplementary References

Reporting Summary

Supplementary Video 1

Heat-assisted healing of TRn11 proteins

Supplementary Video 2

Protein-based pneumatic soft actuator

Supplementary Video 3

Protein-based soft gripper

Supplementary Video 4

Protein-based artificial muscle

Supplementary Video 5

Degradation of protein-based actuators

Supplementary Data 1

Self-healing performance benchmark

Supplementary Data 2

Actuator benchmark

Source data

Source Data Fig. 1b

Unprocessed SDS-PAGE gel from Fig. 1b

Source Data Fig. 1d

Cohesion and network parameter of polypeptides for Fig. 1d

Source Data Fig. 4c

Soft actuator displacement and force output for Fig. 4c

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Pena-Francesch, A., Jung, H., Demirel, M.C. et al. Biosynthetic self-healing materials for soft machines. Nat. Mater. (2020).

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