Review Article | Published:


3D printing of soft robotic systems

Nature Reviews Materialsvolume 3pages84100 (2018) | Download Citation


Soft robots are capable of mimicking the complex motion of animals. Soft robotic systems are defined by their compliance, which allows for continuous and often responsive localized deformation. These features make soft robots especially interesting for integration with human tissues, for example, the implementation of biomedical devices, and for robotic performance in harsh or uncertain environments, for example, exploration in confined spaces or locomotion on uneven terrain. Advances in soft materials and additive manufacturing technologies have enabled the design of soft robots with sophisticated capabilities, such as jumping, complex 3D movements, gripping and releasing. In this Review, we examine the essential soft material properties for different elements of soft robots, highlighting the most relevant polymer systems. Advantages and limitations of different additive manufacturing processes, including 3D printing, fused deposition modelling, direct ink writing, selective laser sintering, inkjet printing and stereolithography, are discussed, and the different techniques are investigated for their application in soft robotic fabrication. Finally, we explore integrated robotic systems and give an outlook for the future of the field and remaining challenges.

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  1. 1.

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

  2. 2.

    Trivedi, D., Rahn, C. D., Kier, W. M. & Walker, I. D. Soft robotics: biological inspiration, state of the art, and future research. Appl. Bionics Biomech. 5, 99–117 (2008).

  3. 3.

    Polygerinos, P., Wang, Z., Galloway, K. C., Wood, R. J. & Walsh, C. J. Soft robotic glove for combined assistance and at-home rehabilitation. Rob. Auton. Syst 73, 135–143 (2015).

  4. 4.

    Shepherd, R. F. et al. Multigait soft robot. Proc. Natl Acad. Sci. USA 108, 20400–20403 (2011).

  5. 5.

    Rosset, S. & Shea, H. R. Flexible and stretchable electrodes for dielectric elastomer actuators. Appl. Phys. A 110, 281–307 (2012).

  6. 6.

    Palleau, E., Morales, D., Dickey, M. D. & Velev, O. D. Reversible patterning and actuation of hydrogels by electrically assisted ionoprinting. Nat. Commun. 4, 2257 (2013).

  7. 7.

    Schumacher, C. M., Loepfe, M., Fuhrer, R., Grass, R. N. & Stark, W. J. 3D printed lost-wax casted soft silicone monoblocks enable heart-inspired pumping by internal combustion. RSC Adv. 4, 16039 (2014).

  8. 8.

    Katzschmann, R. K., Marchese, A. D. & Rus, D. Hydraulic autonomous soft robotic fish for 3D Swimming. Experimental Robotics 109, 405–420 (2014).

  9. 9.

    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).

  10. 10.

    Zhao, H., Li, Y., Elsamadisi, A. & Shepherd, R. Scalable manufacturing of high force wearable soft actuators. Extreme Mech. Lett. 3, 89–104 (2015).

  11. 11.

    Mac Murray, B. C. et al. Poroelastic foams for simple fabrication of complex soft robots. Adv. Mater. 27, 6334–6340 (2015).

  12. 12.

    Morrow, J., Hemleben, S. & Menguc, Y. Directly fabricating soft robotic actuators with an open-source 3D Printer. IEEE Robot. Autom. Lett. 2, 277–281 (2016).

  13. 13.

    Peele, B. N., Wallin, T. J., Zhao, H. & Shepherd, R. F. 3D printing antagonistic systems of artificial muscle using projection stereolithography. Bioinspir. Biomim. 10, 55003 (2015).

  14. 14.

    Kim, S., Laschi, C. & Trimmer, B. Soft robotics: a bioinspired evolution in robotics. Trends Biotechnol. 31, 287–294 (2013).

  15. 15.

    Laschi, C., Mazzolai, B., Mattoli, V., Cianchetti, M. & Dario, P. Design of a biomimetic robotic octopus arm. Bioinspir. Biomim. 4, 15006 (2009).

  16. 16.

    Raibert, M. BigDog, the rough-terrain quadruped robot. IFAC Proceedings Volumes 4, 10822–10825 (2008).

  17. 17.

    Grimes, J. & Hurst, J. The design of atrias 1.0 a unique monopod, hopping robot. Proceedings of the 15th International conference on climbing and walking robots and the support technologies for mobile machines (2012).

  18. 18.

    Seok, S. et al. Meshworm: a peristaltic soft robot with antagonistic nickel titanium coil actuators. IEEE/ASME Transactions on Mechatronics 18, 1485–1497 (2013).

  19. 19.

    Laschi, C. et al. Soft robot arm inspired by the octopus. Adv. Robot. 26, 709–727 (2012).

  20. 20.

    Morin, Sa et al. Camouflage and display for soft machines. Science 337, 828–832 (2012).

  21. 21.

    Pikul, A. J. H. et al. Stretchable surfaces with programmable 3D texture morphing for synthetic camouflaging skins. Science 358, 210–214 (2017).

  22. 22.

    Norman, M. D., Finn, J. & Tregenza, T. Dynamic mimicry in an Indo-Malayan octopus. Proc. Biol. Sci. 268, 1755–1758 (2001).

  23. 23.

    Walker, I. D. et al. Continuum robot arms inspired by cephalopods. Proceedings of SPIE 5804, 303 (2005).

  24. 24.

    Onal, C. D. & Rus, D. Autonomous undulatory serpentine locomotion utilizing body dynamics of a fluidic soft robot. Bioinspir. Biomim. 8, 26003 (2013).

  25. 25.

    Keplinger, C., Li, T., Baumgartner, R., Suo, Z. & Bauer, S. Harnessing snap-through instability in soft dielectrics to achieve giant voltage-triggered deformation. Soft Matter 8, 285–288 (2012).

  26. 26.

    Follador, M., Cianchetti, M. & Laschi, C. Development of the functional unit of a completely soft octopus-like robotic arm. BioRob (2012).

  27. 27.

    Lessing, J., Morin, S. A., Keplinger, C., Tayi, A. S. & Whitesides, G. M. Stretchable conductive composites based on metal wools for use as electrical vias in soft devices. Adv. Funct. Mater. 25, 1418–1425 (2012).

  28. 28.

    Magdassi, S. in The Chemistry of Inkjet inks (ed. Magdassi, S.) 19–43 (World Scientific Pubishing Co. Pte. Ltd., Singapore, 2010).

  29. 29.

    Guo, Y., Ji, Z., Zhang, Y., Wang, X. & Zhou, F. Solvent-free and photocurable polyimide inks for 3D printing. J. Mater. Chem. 5, 16307–16314 (2017).

  30. 30.

    Compton, B. G. & Lewis, J. A. 3D-printing of lightweight cellular composites. Adv. Mater. 26, 5930–5935 (2014).

  31. 31.

    Shemelya, C. et al. 3D printed capacitive sensors. In 2013 Ieee Sensors 3, 1–4 (2013).

  32. 32.

    Leigh, S. J., Bradley, R. J., Purssell, C. P., Billson, D. R. & Hutchins, D. A. A. Simple, low-cost conductive composite material for 3d printing of electronic sensors. PLoS ONE 7, 1–6 (2012).

  33. 33.

    Engels, H. W. et al. Polyurethanes: versatile materials and sustainable problem solvers for today’s challenges. Angew. Chem. Int. Ed. 52, 9422–9441 (2013).

  34. 34.

    Mark, J. E. Overview of siloxane polymers. ACS Symposium Series 729, 1–10 (2000).

  35. 35.

    Lee, J. N., Park, C. & Whitesides, G. M. Solvent compatibility of poly(dimethylsiloxane)-based microfluidic devices. Anal. Chem. 75, 6544–6554 (2003).

  36. 36.

    Keplinger, C. et al. Stretchable, transparent, ionic conductors. Science 341, 984–987 (2013).

  37. 37.

    Marchese, A. D., Katzschmann, R. K. & Rus, D. A. Recipe for soft fluidic elastomer robots. Soft Robot. 2, 7–25 (2015).

  38. 38.

    Cho, K. J. et al. Review of manufacturing processes for soft biomimetic robots. Int. J. Precis. Eng. Manuf. 10, 171–181 (2009).

  39. 39.

    Shepherd, R. F., Stokes, A. A., Nunes, R. M. D. & Whitesides, G. M. Soft machines that are resistant to puncture and that self seal. Adv. Mater. 25, 6709–6713 (2013).

  40. 40.

    Lin, H.-T., Leisk, G. G. & Trimmer, B. GoQBot: a caterpillar-inspired soft-bodied rolling robot. Bioinspir. Biomim 6, 26007 (2011).

  41. 41.

    Morin, S. A. et al. Using ‘click-e-Bricks’ to make 3D elastomeric structures. Adv. Mater. 26, 5991–5999 (2014).

  42. 42.

    Deimel, R. & Brock, O. A novel type of compliant and underactuated robotic hand for dexterous grasping. Int. J. Rob. Res. 35, 161–185 (2016).

  43. 43.

    Zhao, H., O’Brien, K., Li, S. & Shepherd, R. F. Optoelectronically innervated soft prosthetic hand via stretchable optical waveguides. Sci. Robot. 1, eaai7529 (2016).

  44. 44.

    Mosadegh, B. et al. Pneumatic networks for soft robotics that actuate rapidly. Adv. Funct. Mat. 24, 2163–2170 (2014).

  45. 45.

    Wirthl, D. et al. Engineering instant tough bonding of hydrogels for soft machines and electronics. Sci. Adv. 3, e1700053 (2017).

  46. 46.

    Yuk, H., Zhang, T., Parada, G. A., Liu, X. & Zhao, X. Skin-inspired hydrogel–elastomer hybrids with robust interfaces and functional microstructures. Nat. Commun. 7, 12028 (2016).

  47. 47.

    Eddings, M. A., Johnson, M. A. & Gale, B. K. Determining the optimal PDMS–PDMS bonding technique for microfluidic devices. J. Micromech. Microeng. 18, 67001 (2008).

  48. 48.

    Marchese, A. D., Onal, C. D. & Rus, D. Autonomous soft robotic fish capable of escape maneuvers using fluidic elastomer actuators. Soft Robot 1, 75–87 (2014).

  49. 49.

    Jiang, Y. & Wang, Q. Highly-stretchable 3D-architected mechanical metamaterials. Sci. Rep 6, 34147 (2016).

  50. 50.

    Loepfe, M., Schumacher, C. M., Burri, C. H. & Stark, W. J. Contrast agent incorporation into silicone enables real-time flow-structure analysis of mammalian vein-inspired soft pumps. Adv. Funct. Mater. 25, 2129–2137 (2015).

  51. 51.

    Loepfe, M., Schumacher, C. M. & Stark, W. J. Design, performance and reinforcement of bearing-free soft silicone combustion-driven pumps. Ind. Eng. Chem. Res. 53, 12519–12526 (2014).

  52. 52.

    Therriault, D., Shepherd, R. F., White, S. R. & Lewis, J. A. Fugitive inks for direct-write assembly of three-dimensional microvascular networks. Adv. Mater. 17, 395–399 (2005).

  53. 53.

    Valentin, T. M. et al. Stereolithographic printing of ionically-crosslinked alginate hydrogels for degradable biomaterials and microfluidics. Lab. Chip 17, 3474–3488 (2017).

  54. 54.

    Van Meerbeek, I. M. et al. Morphing metal and elastomer bicontinuous foams for reversible stiffness, shape memory, and self-healing soft machines. Adv. Mater. 28, 2801–2806 (2016).

  55. 55.

    Argiolas, A. et al. Sculpting soft machines. Soft Robot. 3, 101–108 (2016).

  56. 56.

    Robertson, M. A. & Paik, J. New soft robots really suck: vacuum-powered systems empower diverse capabilities. Tech Xplore (2017).

  57. 57.

    Yang, W. G. et al. Advanced shape memory technology to reshape product design, manufacturing and recycling. Polymers 6, 2287–2308 (2014).

  58. 58.

    NinjaTek. NinjaFlex ® 3D printing filament: flexible polyurethane material for FDM printers. NinjaTek (2016).

  59. 59.

    Yap, H. K., Ng, H. Y. & Yeow, C.-H. High-force soft printable pneumatics for soft robotic applications. Soft Robot. 3, 144–158 (2016). (2016). This paper provides an overview of the design rules for using FDM to print high-force fluidic elastomer actuators.

  60. 60.

    Mutlu, R., Alici, G. & Spinks, G. M. 3D printed flexure hinges for soft monolithic prosthetic fingers. Soft Robot. 3, 120–133 (2016).

  61. 61.

    Mohamed, O. A., Masood, S. H. & Bhowmik, J. L. Optimization of fused deposition modeling process parameters: a review of current research and future prospects. Adv. Manuf. 3, 42–53 (2015).

  62. 62.

    Kim, C. J. & Pratt, S. T. Dynamically controlled screw-driven extrusion. US Patent 0200024 (2016).

  63. 63.

    Lewis, J. A. Direct ink writing of 3D functional materials. Adv. Funct. Mater. 16, 2193–2204 (2006).

  64. 64.

    Barry, R. A. et al. Direct-write assembly of 3D hydrogel scaffolds for guided cell growth. Adv. Mater. 21, 2407–2410 (2009).

  65. 65.

    Tibbits, S. 4D printing: Multi-material shape change. Architectural Design. 84, 116–121 (2014).

  66. 66.

    Ebara, M. et al. in Smart Biomaterials 9–65 (Springer Japan, 2014).

  67. 67.

    Bakarich, S. E. et al. 3D printing of tough hydrogel composites with spatially varying materials properties. Addit. Manuf. 14, 24–30 (2016).

  68. 68.

    Bakarich, S. E., Gorkin, R. & Spinks, M. Three-dimensional printing fiber reinforced hydrogel composites. ACS Appl. Mater. Interfaces 6, 15998–16006 (2014).

  69. 69.

    Bakarich, S. E., Gorkin, R., in het Panhuis, M. & Spinks, G. M. 4D printing with mechanically robust, thermally actuating hydrogels. Macromol. Rapid Commun. 36, 1211–1217 (2015).

  70. 70.

    Sydney Gladman, A., Matsumoto, E. A., Nuzzo, R. G., Mahadevan, L. & Lewis, J. A. Biomimetic 4D printing. Nat. Mater. 15, 413–418 (2016). This paper exploits anisotropy in DIW printing to create biomimetic active structures.

  71. 71.

    Yuk, H. et al. Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water. Nat. Commun. 8, 14230 (2017).

  72. 72.

    Bakarich, S. E., in het Panhuis, M., Beirne, S., Wallace, G. G. & Spinks, G. M. Extrusion printing of ionic–covalent entanglement hydrogels with high toughness. J. Mater. Chem. B 1, 4939 (2013).

  73. 73.

    Sun, J.-Y. et al. Highly stretchable and tough hydrogels. Nature 489, 133–136 (2012).

  74. 74.

    Plott, J. & Shih, A. The extrusion-based additive manufacturing of moisture-cured silicone elastomer with minimal void for pneumatic actuators. Addit. Manuf. 17, 1–14 (2017).

  75. 75.

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

  76. 76.

    Truby, R. L. & Lewis, J. A. Printing soft matter in three dimensions. Nature 540, 371–378 (2016).

  77. 77.

    Gul, J. Z., Yang, B.-S., Yang, Y. J., Chang, D. E. & Choi, K. H. In situ UV curable 3D printing of multi-material tri-legged soft bot with spider mimicked multi-step forward dynamic gait. Smart Mater. Struct. 25, 115009 (2016).

  78. 78.

    Hinton, T. J., Hudson, A., Pusch, K., Lee, A. & Feinberg, A. W. 3D Printing PDMS elastomer in a hydrophilic support bath via freeform reversible embedding. ACS Biomater. Sci. Eng. 2, 1781–1786 (2016).

  79. 79.

    Hinton, T. J. et al. Three-dimensional printing of complex biological structures by freeform reversible embedding of suspended hydrogels. Sci. Adv. 1, e1500758 (2015).

  80. 80.

    Coward, T., Jindal, S., Waters, M. & Smay, J. 3D printing of facial prostheses. Patent WO107333 (2015).

  81. 81.

    Rost, A. & Schaedle, S. The SLS-generated soft robotic hand - an integrated approach using additive manufacturing and reinforcement learning. Proceedings of the12th ICMLA 2013 (2013).

  82. 82.

    Materialise. Laser sintering material properties. Materialise (2013).

  83. 83.

    Scharff, R. B. N. et al. Towards behavior design of a 3D-printed soft robotic hand. Soft Robot. Trends Application and Challenges 17, 23–29 (2017). This book chapter describes the method and design rules for using SLS to print a soft robotic hand.

  84. 84.

    Jäntsch, M. et al. Anthrob – a printed anthropomimetic robot. 13th IEEE-RAS International Conference on Humanoid Robots (Humanoids) (2013).

  85. 85.

    Mazzoli, A. Selective laser sintering in biomedical engineering. Med. Biol. Eng. Comput. 51, 245–256 (2013).

  86. 86.

    Yuan, C., Wang, T., Dunn, M. L. & Qi, H. J. 3D printed active origami with complicated folding patterns. International Journal of Precision Engineering and Manufacturing-Green Technology 4, 281–289 (2017).

  87. 87.

    Yu, K., Dunn, M. L. & Qi, H. J. Digital manufacture of shape changing components. Extreme Mech. Lett. 4, 9–17 (2015).

  88. 88.

    Wu, J. et al. Multi-shape active composites by 3D printing of digital shape memory polymers. Sci. Rep. 6, 31110 (2016).

  89. 89.

    Mao, Y. et al. Sequential self-folding structures by 3D printed digital shape memory polymers. Sci. Rep. 5, 13616 (2015).

  90. 90.

    Umedachi, T., Vikas, V. & Trimmer, B. A. Softworms: the design and control of non-pneumatic, 3D-printed, deformable robots. Bioinspir. Biomim 11, 25001 (2016).

  91. 91.

    Umedachi, T., Vikas, V. & Trimmer, B. A. Highly deformable 3D printed soft robot generating inching and crawling locomotions with variable friction legs. IEEE/RSJ International Conference on IROS (2013).

  92. 92.

    Phamduy, P. et al. Design and characterization of a miniature free-swimming robotic fish based on multi-material 3D printing. Int. J. Intell. Robot. Appl. 1, 209–223 (2017).

  93. 93.

    Drotman, D., Jadhav, S., Karimi, M., deZonia, P. & Tolley, M. T. 3D printed soft actuators for a legged robot capable of navigating unstructured terrain. 2017i EEE ICRA. (2017).

  94. 94.

    Maccurdy, R., Katzschmann, R., Kim, Y. & Rus, D. Printable hydraulics: a method for fabricating robots by 3D co-printing solids and liquids. 2016 IEEE ICRA (2016). This paper describes how to incorporate a fugitive, hydraulic fluid into a multi-material print to integrate power and actuating systems

  95. 95.

    Stratasys. PolyJet materials data sheet. Stratasys (2015).

  96. 96.

    Bartlett, N. W. et al. A 3D printed, functionalled graded soft robot powered by combustion. Science 349, 161–165 (2015). In this paper, multi-material inkjet printing is used to create mechanical gradients for the fabrication of a combustion-powered soft jumping robot.

  97. 97.

    Derby, B. Inkjet printing of functional and structural materials: fluid property requirements, feature stability, and resolution. Annu. Rev. Mater. Res. 40, 395–414 (2010).

  98. 98.

    Park, S. H., Yang, D. Y. & Lee, K. S. Two-photon stereolithography for realizing ultraprecise three-dimensional nano/microdevices. Laser Photonics Rev. 3, 1–11 (2009).

  99. 99.

    Beluze, L., Bertsch, A. & Renaud, P. Microstereolithography: a new process to build complex 3D objects. Proc. Soc. Photo- Opt. Instrum. Eng. 1, 808–817 (1999).

  100. 100.

    Yayue P., Zhou, C. & Chen, Y. Rapid manufacturing in minutes: the development of a mask projection stereolithography process for high-speed fabrication. ASME Journal of Engineering and Science in Medical Diagnostics and Therapy (2012).

  101. 101.

    Patel, D. K. et al. Highly stretchable and UV curable elastomers for digital light processing based 3D printing. Adv. Mater. 29, 1606000 (2017). This paper highlights a wide range of custom chemistries compatible with SLA printing that yield soft, highly extensible materials.

  102. 102.

    Tumbleston, J. R. et al. Continuous liquid interface production of 3D objects. Science 347, 1349–1352 (2015).

  103. 103.

    Shusteff, M. et al. One-step volumetric additive manufacturing of complex polymer structures. Sci. Adv. 3, 1–7 (2017).

  104. 104.

    Melchels, F. P. W., Feijen, J. & Grijpma, D. W. A review on stereolithography and its applications in biomedical engineering. Biomaterials 31, 6121–6130 (2010).

  105. 105.

    Kang, H. W., Lee, I. H. & Cho, D. W. Development of a micro-bellows actuator using micro-stereolithography technology. Microelectron. Eng. 83, 1201–1204 (2006).

  106. 106.

    Bartolo, P. J. Stereolithography: Materials, Processes and Applications (Springer Science + Business Media, LLC, NY, 2011).

  107. 107.

    Eckel, Z. C. et al. Additive manufacturing of polymer-derived ceramics. Science 351, 58–62 (2016).

  108. 108.

    CarbonResin EPU 40. EPU 40. SabeRex (2016).

  109. 109.

    Zarek, M. et al. 3D printing of shape memory polymers for flexible electronic devices. Adv. Mater. 28, 4449–4454 (2016).

  110. 110.

    Odent, J. et al. Highly elastic, transparent, and conductive 3D-printed ionic composite hydrogels. Adv. Funct. Mater. 27, 1701807 (2017).

  111. 111.

    Pang, T. H. Stereolithography epoxy resins sl 5170 and sl 5180: accuracy, dimensional stability, and mechanical properties. 3D systems Corp. 65, 204–224 (1994).

  112. 112.

    Jacobs, P. F. Stereolithography and other RP&M technologies from rapid prototyping to rapid tooling (Society of Manufacturing Engineers, NY, 1996).

  113. 113.

    Velankar, S., Pazos, J. & Cooper, S. L. High-performance UV-curable urethane acrylates via deblocking chemistry. J. Appl. Polym. Sci. 62, 1361–1376 (1996).

  114. 114.

    Sinh, L. H. et al. Novel photo-curable polyurethane resin for stereolithography. RSC Adv. 6, 50706–50709 (2016).

  115. 115.

    Hoyle, C. E. & Bowman, C. N. Thiol-ene click chemistry. Angew. Chem. Int. Ed. 49, 1540–1573 (2010).

  116. 116.

    Wallin, T. J. et al. Click chemistry stereolithography for soft robots that self-heal. J. Mater. Chem. B 5, 6249–6255 (2017).

  117. 117.

    Chan, V. et al. Multi-material bio-fabrication of hydrogel cantilevers and actuators with stereolithography. Lab Chip 12, 88–98 (2012).

  118. 118.

    Choi, J. W., Kim, H. C. & Wicker, R. Multi-material stereolithography. J. Mater. Process. Technol. 211, 318–328 (2011).

  119. 119.

    Ge, Q. et al. Multimaterial 4D printing with tailorable shape memory polymers. Sci. Rep. 6, 31110 (2016).

  120. 120.

    Adams, J. J. et al. Conformal printing of electrically small antennas on three-dimensional surfaces. Adv. Mater. 23, 1335–1340 (2011).

  121. 121.

    Guo, S. Z., Qiu, K., Meng, F., Park, S. H. & McAlpine, M. C. 3D Printed stretchable tactile sensors. Adv. Mater. 29, 1–8 (2017).

  122. 122.

    Lorang, D. J. et al. Photocurable liquid core-fugitive shell printing of optical waveguides. Adv. Mater. 23, 5055–5058 (2011).

  123. 123.

    Kokkinis, D., Schaffner, M. & Studart, A. R. Multimaterial magnetically assisted 3D printing of composite materials. Nat. Commun. 6, 8643 (2015).

  124. 124.

    Li, S., Zhao, H. & Shepherd, R. F. Flexible and stretchable sensors for fluidic elastomer actuated soft robots. MRS Bull. 42, 138–142 (2017).

  125. 125.

    Larson, C., Spjut, J., Knepper, R. & Shepherd, R. OrbTouch: recognizing human touch in deformable interfaces with deep neural networks. arXiv (2017).

  126. 126.

    Niklaus, M. & Shea, H. R. Electrical conductivity and Young’s modulus of flexible nanocomposites made by metal-ion implantation of polydimethylsiloxane: the relationship between nanostructure and macroscopic properties. Acta Mater. 59, 830–840 (2011).

  127. 127.

    Chodák, I., Omastová, M. & Pionteck, J. Relation between electrical and mechanical properties of conducting polymer composites. J. Appl. Polym. Sci. 82, 1903–1906 (2001).

  128. 128.

    Kim, D.-H. et al. Epidermal electronics. Science 333, 838–843 (2011).

  129. 129.

    Sekitani, T. et al. A rubberlike stretchable active matrix using elastic conductors. Science 321, 1468–1473 (2008).

  130. 130.

    Kim, H., Sim, K., Thukral, A. & Yu, C. Rubbery electronics and sensors from intrinsically stretchable elastomeric composites of semiconductors and conductors. Sci. Adv. 3, el701114 (2017).

  131. 131.

    Matsuhisa, N. et al. Printable elastic conductors by in situ formation of silver nanoparticles from silver flakes. Nat. Mater. 16, 834–840 (2017).

  132. 132.

    Muth, J. T. et al. Embedded 3D printing of strain sensors within highly stretchable elastomers. Adv. Mater. 26, 6307–6312 (2014).

  133. 133.

    Ladd, C., So, J. H., Muth, J. & Dickey, M. D. 3D printing of free standing liquid metal microstructures. Adv. Mater. 25, 5081–5085 (2013).

  134. 134.

    Boley, J. W., White, E. L., Chiu, G. T. C. & Kramer, R. K. Direct writing of gallium-indium alloy for stretchable electronics. Adv. Funct. Mater. 24, 3501–3507 (2014).

  135. 135.

    Tabatabai, A., Fassler, A., Usiak, C. & Majidi, C. Liquid-phase gallium-indium alloy electronics with microcontact printing. Langmuir 29, 6194–6200 (2013).

  136. 136.

    Sarwar, M. S. et al. Bend, stretch, and touch: locating a finger on an actively deformed transparent sensor array. Sci. Adv. 3, e1602200 (2017).

  137. 137.

    Mannsfeld, S. C. B. et al. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat. Mater. 9, 859–864 (2010).

  138. 138.

    White, E. L., Yuen, M. C., Case, J. C. & Kramer, R. K. Low-cost, facile, and scalable manufacturing of capacitive sensors for soft Systems. Adv. Mater. Technol. 2, 1700072 (2017).

  139. 139.

    Li, S., Peele, B. N., Larson, C. M., Zhao, H. & Shepherd, R. F. A. Stretchable multicolor display and touch interface using photopatterning and transfer printing. Adv. Mater. 28, 9770–9775 (2016).

  140. 140.

    Robinson, S. S. et al. Integrated soft sensors and elastomeric actuators for tactile machines with kinesthetic sense. Extrem. Mech. Lett. 5, 47–53 (2015). This paper details a method for conformally printing capacitive sensors onto fluidic elastomer actuators to create integrated tactile machines.

  141. 141.

    Rossiter, J., Walters, P. & Stoimenov, B. Printing 3D dielectric elastomer actuators for soft robotics. Proc. SPIE 7287, 1–10 (2009).

  142. 142.

    Frutiger, A. et al. Capacitive soft strain sensors via multicore-shell fiber printing. Adv. Mater. 27, 2440–2446 (2015).

  143. 143.

    Luo, M. et al. Slithering towards autonomy: a self-contained soft robotic snake platform with integrated curvature sensing. Bioinspir. Biomim. 10, 55001 (2015).

  144. 144.

    Ozel, S. et al. A composite soft bending actuation module with integrated curvature sensing. 2016 IEEE ICRA (2016).

  145. 145.

    Tao, W. et al. Bioinspired design and fabrication principles of reliable fluidic soft actuation modules. 2015 IEEE ROBIO (2015).

  146. 146.

    Wang, H. et al. A low-cost soft tactile sensing array using 3D hall sensors. Procedia Eng. 168, 650–653 (2016).

  147. 147.

    Wang, H. et al. Design methodology for magnetic field-based soft tri-axis tactile sensors. Sensors 16, E1356 (2016).

  148. 148.

    Slyper, R. & Hodgins, J. Prototyping robot appearance, movement, and interactions using flexible 3D printing and air pressure sensors. 2012 IEEE RO-MAN (2012).

  149. 149.

    Samusjew, A. et al. Inkjet printing of soft, stretchable pptical waveguides through the photopolymerization of high-profile linear patterns. ACS Appl. Mater. Interfaces 9, 4941–4947 (2017).

  150. 150.

    Yin, M. J. et al. Rapid 3D patterning of poly(acrylic acid) ionic hydrogel for miniature pH sensors. Adv. Mater. 28, 1394–1399 (2016).

  151. 151.

    Shepherd, R. Highly stretchable electroluminescent skin for optical signaling and tactile sensing. Science 351, 1071–1074 (2016).

  152. 152.

    Wehner, M. et al. An integrated design and fabrication strategy for entirely soft, autonomous robots. Nature 536, 451–455 (2016). This paper details a design strategy to integrate control, power and actuating systems in a single manufacturing process.

  153. 153.

    Sadeghi, A., Tonazzini, A., Popova, L. & Mazzolai, B. A novel growing device inspired by plant root soil penetration behaviors. PLoS ONE 9, e90139 (2014).

  154. 154.

    Sadeghi, A., Mondini, A. & Mazzolai, B. Toward self-growing soft robots inspired by plant roots and based on additive manufacturing technologies. Soft Robot. 4, 211–223 (2017). This paper describes the growth of a robot using a mobile, on-board FDM printer.

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The authors thank the Air Force Office of Scientific Research (Young Investigator Award under Award Number FA9550-15-1-0160), the Office of Naval Research (Young Investigator Award under Award Number N00014-17-1-2837) and the National Science Foundation (under Award Number CMMI-1537413) for their support.

Author information


  1. Department of Materials Science & Engineering, Cornell University, Ithaca, NY, USA

    • T. J. Wallin
  2. Sibley School of Aerospace & Mechanical Engineering, Cornell University, Ithaca, NY, USA

    • J. Pikul
    •  & R. F. Shepherd


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All authors contributed equally to the preparation of this manuscript.

Competing interests

This Review appropriately references an article “Click chemistry stereolithography for soft robots that self-heal.” J. Mat. Chem. B (2017). Portions of this referenced work have been disclosed to the United States Patent and Trademark Office as Provisional Patent 62/369,327: Polymer Compositions for 3D printing and 3D. Two of the authors, R.S. and T.W., are inventors on this patent.

Corresponding author

Correspondence to R. F. Shepherd.

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