Morphing in nature and beyond: a review of natural and synthetic shape-changing materials and mechanisms
Source abstract
Abstract
Shape-changing materials open an entirely new solution space for a wide range of disciplines: from architecture that responds to the environment and medical devices that unpack inside the body, to passive sensors and novel robotic actuators. While synthetic shape-changing materials are still in their infancy, studies of biological morphing materials have revealed key paradigms and features which underlie efficient natural shape-change. Here, we review some of these insights and how they have been, or may be, translated to artificial solutions. We focus on soft matter due to its prevalence in nature, compatibility with users and potential for novel design. Initially, we review examples of natural shape-changing materials—skeletal muscle, tendons and plant tissues—and compare with synthetic examples with similar methods of operation. Stimuli to motion are outlined in general principle, with examples of their use and potential in manufactured systems. Anisotropy is identified as a crucial element in directing shape-change to fulfil designed tasks, and some manufacturing routes to its achievement are highlighted. We conclude with potential directions for future work, including the simultaneous development of materials and manufacturing techniques and the hierarchical combination of effects at multiple length scales.
Source: openalex_inverted_index · Quality: baseline
Research context
OpenAlex topics: Advanced Materials and Mechanics · Advanced Sensor and Energy Harvesting Materials · Polymer composites and self-healing
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (100+)
Show source-provided references
1. Nova A, Keten S, Pugno NM, Redaelli A, Buehler MJ (2010) Molecular and nanostructural mechanisms of deformation, strength and toughness of spider silk fibrils. Nano Lett 10:2626–2634. doi: 10.1021/nl101341w10.1021/nl101341w ↗
2. Rho J-Y, Kuhn-Spearing L, Zioupos P (1998) Mechanical properties and the hierarchical structure of bone. Med Eng Phys 20:92–102. doi: 10.1016/S1350-4533(98)00007-110.1016/S1350-4533(98)00007-1 ↗
3. Saranathan V, Osuji CO, Mochrie SGJ, Noh H, Narayanan S, Sandy A, Dufresne ER, Prum RO (2010) Structure, function, and self-assembly of single network gyroid (I4132) photonic crystals in butterfly wing scales. Proc Natl Acad Sci USA 107:11676–11681. doi: 10.1073/pnas.090961610710.1073/pnas.0909616107 ↗
4. Allen JJ, Bell GRR, Kuzirian AM, Hanlon RT (2013) Cuttlefish skin papilla morphology suggests a muscular hydrostatic function for rapid changeability. J Morphol 274:645–656. doi: 10.1002/jmor.2012110.1002/jmor.20121 ↗
5. Lee H, Lee BP, Messersmith PB (2007) A reversible wet/dry adhesive inspired by mussels and geckos. Nature 448:338–341. doi: 10.1038/nature0596810.1038/nature05968 ↗
6. Mohd Jani J, Leary M, Subic A, Gibson MA (2014) A review of shape memory alloy research, applications and opportunities. Mater Des 56:1078–1113. doi: 10.1016/j.matdes.2013.11.08410.1016/j.matdes.2013.11.084 ↗
7. Irschik H (2002) A review on static and dynamic shape control of structures by piezoelectric actuation. Eng Struct 24:5–11. doi: 10.1016/S0141-0296(01)00081-510.1016/S0141-0296(01)00081-5 ↗
8. Doi M (2013) Soft matter physics. OUP, Oxford10.1093/acprof:oso/9780199652952.001.0001 ↗
9. Quake SR (2000) From micro- to nanofabrication with soft materials. Science 290:1536–1540. doi: 10.1126/science.290.5496.153610.1126/science.290.5496.1536 ↗
10. Bauer S, Bauer-Gogonea S, Graz I, Kaltenbrunner M, Keplinger C, Schwödiauer R (2014) 25th anniversary article: a soft future: from robots and sensor skin to energy harvesters. Adv Mater 26:149–161. doi: 10.1002/adma.20130334910.1002/adma.201303349 ↗
11. Rus D, Tolley MT (2015) Design, fabrication and control of soft robots. Nature 521:467–475. doi: 10.1038/nature1454310.1038/nature14543 ↗
12. Deligkaris K, Tadele TS, Olthuis W, van den Berg A (2010) Hydrogel-based devices for biomedical applications. Sens Actuators B 147:765–774. doi: 10.1016/j.snb.2010.03.08310.1016/j.snb.2010.03.083 ↗
13. Holstov A, Bridgens B, Farmer G (2015) Hygromorphic materials for sustainable responsive architecture. Constr Build Mater 98:570–582. doi: 10.1016/j.conbuildmat.2015.08.13610.1016/j.conbuildmat.2015.08.136 ↗
14. Zarzar LD, Kim P, Aizenberg J (2011) Bio-inspired design of submerged hydrogel-actuated polymer microstructures operating in response to pH. Adv Mater 23:1442–1446. doi: 10.1002/adma.20100423110.1002/adma.201004231 ↗
15. Yao L, Ou J, Cheng C-Y, Steiner H, Wang W, Wang G, Ishii H (2015) BioLogic. In: Proceedings of the 33rd annual ACM conference on human factors computing systems—CHI’15. ACM Press, New York, pp 1–1010.1145/2702123.2702611 ↗
16. Kim S, Laschi C, Trimmer B (2013) Soft robotics: a bioinspired evolution in robotics. Trends Biotechnol 31:287–294. doi: 10.1016/j.tibtech.2013.03.00210.1016/j.tibtech.2013.03.002 ↗
17. Evangelista D, Hotton S, Dumais J (2011) The mechanics of explosive dispersal and self-burial in the seeds of the filaree, Erodium cicutarium (Geraniaceae). J Exp Biol 214:521–529. doi: 10.1242/jeb.05056710.1242/jeb.050567 ↗
18. Reyssat E, Mahadevan L (2009) Hygromorphs: from pine cones to biomimetic bilayers. J R Soc Interface 6:951–957. doi: 10.1098/rsif.2009.018410.1098/rsif.2009.0184 ↗
19. Rafsanjani A, Brulé V, Western TL, Pasini D (2015) Hydro-responsive curling of the resurrection plant Selaginella lepidophylla. Sci Rep 5:8064. doi: 10.1038/srep0806410.1038/srep08064 ↗
20. Timoshenko S (1925) Analysis of bi-metal thermostats. J Opt Soc Am 11:233–255. doi: 10.1364/JOSA.11.00023310.1364/JOSA.11.000233 ↗
21. Hu Z, Zhang X, Li Y (1995) Synthesis and application of modulated polymer gels. Science 269:525–527. doi: 10.1126/science.269.5223.52510.1126/science.269.5223.525 ↗
22. Guvendiren M, Yang S, Burdick JA (2009) Swelling-induced surface patterns in hydrogels with gradient crosslinking density. Adv Funct Mater 19:3038–3045. doi: 10.1002/adfm.20090062210.1002/adfm.200900622 ↗
23. Studart AR, Erb RM (2014) Bioinspired materials that self-shape through programmed microstructures. Soft Matter 10:1284–1294. doi: 10.1039/c3sm51883c10.1039/c3sm51883c ↗
24. Bar-On B, Sui X, Livanov K, Achrai B, Kalfon-Cohen E, Wiesel E, Wagner HD (2014) Structural origins of morphing in plant tissues. Appl Phys Lett 105:033703. doi: 10.1063/1.489119110.1063/1.4891191 ↗
25. Abraham Y, Tamburu C, Klein E, Dunlop JWC, Fratzl P, Raviv U, Elbaum R (2012) Tilted cellulose arrangement as a novel mechanism for hygroscopic coiling in the stork’s bill awn. J R Soc Interface 9:640–647. doi: 10.1098/rsif.2011.039510.1098/rsif.2011.0395 ↗
26. Aharoni H, Abraham Y, Elbaum R, Sharon E, Kupferman R (2012) Emergence of spontaneous twist and curvature in non-euclidean rods: application to erodium plant cells. Phys Rev Lett 108:238106. doi: 10.1103/PhysRevLett.108.23810610.1103/PhysRevLett.108.238106 ↗
27. Knight DP, Vollrath F (2002) Biological liquid crystal elastomers. Philos Trans R Soc Lond B 357:155–163. doi: 10.1098/rstb.2001.103010.1098/rstb.2001.1030 ↗
28. Behl M, Lendlein A (2007) Shape-memory polymers. Mater Today 10:20–28. doi: 10.1016/S1369-7021(07)70047-010.1016/S1369-7021(07)70047-0 ↗
29. Ahn S, Kasi RM, Kim S-C, Sharma N, Zhou Y (2008) Stimuli-responsive polymer gels. Soft Matter 4:1151–1157. doi: 10.1039/b714376a10.1039/b714376a ↗
30. Geryak R, Tsukruk VV (2014) Reconfigurable and actuating structures from soft materials. Soft Matter 10:1246–1263. doi: 10.1039/c3sm51768c10.1039/c3sm51768c ↗
31. Meng H, Li G (2013) A review of stimuli-responsive shape memory polymer composites. Polymer (Guildf) 54:2199–2221. doi: 10.1016/j.polymer.2013.02.02310.1016/j.polymer.2013.02.023 ↗
32. Ionov L (2014) Polymeric actuators. Langmuir 31:5015–5024. doi: 10.1021/la503407z10.1021/la503407z ↗
33. Lodish H, Kaiser C, Bretscher A, Amon A, Berk A, Krieger M, Polegh H, Scott M (2013) Myosin thick filaments and actin thin filaments in skeletal muscle slide past one another during contraction. In: Molecular cell biology, 7th edn. W. H. Freeman and Co, New York, p 801–802
34. Meyers MA, Chen P-Y, Lin AY-M, Seki Y (2008) Biological materials: structure and mechanical properties. Prog Mater Sci 53:1–206. doi: 10.1016/j.pmatsci.2007.05.00210.1016/j.pmatsci.2007.05.002 ↗
35. Wainwright PC, Kraklau DM, Bennett AF (1991) Kinematics of tongue projection in Chamaeleo oustaleti. J Exp Biol 159:109–13310.1242/jeb.159.1.109 ↗
36. Vogel S (2003) Achieving motility. In: Vogel S (ed) Comparative biomechanics—life’s physical world. Princeton University Press, Princeton, pp 453–582
37. White TJ, Broer DJ (2015) Programmable and adaptive mechanics with liquid crystal polymer networks and elastomers. Nat Mater 14:1087–1098. doi: 10.1038/nmat443310.1038/nmat4433 ↗
38. Shahinpoor M, Bar-Cohen Y, Simpson JO, Smith J (1998) Ionic polymer-metal composites (IPMCs) as biomimetic sensors, actuators and artificial muscles—a review. Smart Mater Struct 7:R15–R30. doi: 10.1088/0964-1726/7/6/00110.1088/0964-1726/7/6/001 ↗
39. Bar-Cohen Y (2004) Electroactive polymer (EAP) actuators as artificial muscles: reality, potential, and challenges. Electroact Polym. doi: 10.1117/3.54746510.1117/3.547465 ↗
40. Pugal D, Jung K, Aabloo A, Kim KJ (2010) Ionic polymer-metal composite mechanoelectrical transduction: review and perspectives. Polym Int 59:279–289. doi: 10.1002/pi.275910.1002/pi.2759 ↗
41. Bahramzadeh Y, Shahinpoor M (2014) A review of ionic polymeric soft actuators and sensors. Soft Robot 1:38–52. doi: 10.1089/soro.2013.000610.1089/soro.2013.0006 ↗
42. Brochu P, Pei Q (2010) Advances in dielectric elastomers for actuators and artificial muscles. Macromol Rapid Commun 31:10–36. doi: 10.1002/marc.20090042510.1002/marc.200900425 ↗
43. de Gennes P-G (1997) Un muscle artificiel semi-rapide. Comptes Rendus l’Académie des Sci—Ser IIB—Mech 324:343–348. doi: 10.1016/S1251-8069(99)80044-X10.1016/S1251-8069(99)80044-X ↗
44. Li M-H, Keller P (2006) Artificial muscles based on liquid crystal elastomers. Philos Trans A 364:2763–2777. doi: 10.1098/rsta.2006.185310.1098/rsta.2006.1853 ↗
45. Thomsen DL, Keller P, Naciri J, Pink R, Jeon H, Shenoy D, Ratna BR (2001) Liquid crystal elastomers with mechanical properties of a muscle. Macromolecules 34:5868–5875. doi: 10.1021/ma001639q10.1021/ma001639q ↗
46. Shahsavan H, Salili SM, Jákli A, Zhao B (2015) Smart muscle-driven self-cleaning of biomimetic microstructures from liquid crystal elastomers. Adv Mater 27:6828–6833. doi: 10.1002/adma.20150320310.1002/adma.201503203 ↗
47. Agrawal A, Chipara AC, Shamoo Y, Patra PK, Carey BJ, Ajayan PM, Chapman WG, Verduzco R (2013) Dynamic self-stiffening in liquid crystal elastomers. Nat Commun 4:1739. doi: 10.1038/ncomms277210.1038/ncomms2772 ↗
48. Iwamoto H, Inoue K, Yagi N (2006) Evolution of long-range myofibrillar crystallinity in insect flight muscle as examined by X-ray cryomicrodiffraction. Proc Biol Sci 273:677–685. doi: 10.1098/rspb.2005.338910.1098/rspb.2005.3389 ↗
49. Seddon JM, Squires AM, Conn CE, Ces O, Heron AJ, Mulet X, Shearman GC, Templer RH (2006) Pressure-jump X-ray studies of liquid crystal transitions in lipids. Philos Trans A 364:2635–2655. doi: 10.1098/rsta.2006.184410.1098/rsta.2006.1844 ↗
50. Küpfer J, Finkelmann H (1991) Nematic liquid single crystal elastomers. Die Makromol Chemie Rapid Commun 12:717–726. doi: 10.1002/marc.1991.03012121110.1002/marc.1991.030121211 ↗
51. Ohm C, Brehmer M, Zentel R (2010) Liquid crystalline elastomers as actuators and sensors. Adv Mater 22:3366–3387. doi: 10.1002/adma.20090405910.1002/adma.200904059 ↗
52. Hogan PM, Tajbakhsh AR, Terentjev EM (2002) UV manipulation of order and macroscopic shape in nematic elastomers. Phys Rev E 65:1–8. doi: 10.1103/PhysRevE.65.04172010.1103/PhysRevE.65.041720 ↗
53. Tsutsumi O, Shiono T, Tomiki I, Galli G (1997) Photochemical phase transition behavior of nematic liquid crystals with azobenzene moieties as both mesogens and photosensitive chromophores. J Phys Chem B 101:1332–1337. doi: 10.1021/jp961565d10.1021/jp961565d ↗
54. Kempe MD, Scruggs NR, Verduzco R, Lal J, Kornfield JA (2004) Self-assembled liquid-crystalline gels designed from the bottom up. Nat Mater 3:177–182. doi: 10.1038/nmat107410.1038/nmat1074 ↗
55. Jiang H, Li C, Huang X (2013) Actuators based on liquid crystalline elastomer materials. Nanoscale 5:5225–5240. doi: 10.1039/c3nr00037k10.1039/c3nr00037k ↗
56. Chambers M, Finkelmann H, Remškar M, Sánchez-Ferrer A, Zalar B, Žumer S (2009) Liquid crystal elastomer–nanoparticle systems for actuation. J Mater Chem 19:1524–1531. doi: 10.1039/B812423J10.1039/B812423J ↗
57. Urayama K (2007) Selected issues in liquid crystal elastomers and gels. Macromolecules 40:2277–2288. doi: 10.1021/ma062368810.1021/ma0623688 ↗
58. Sawa Y, Ye F, Urayama K, Takigawa T, Gimenez-Pinto V, Selinger RLB, Selinger JV (2011) Shape selection of twist-nematic-elastomer ribbons. Proc Natl Acad Sci USA 108:6364–6368. doi: 10.1073/pnas.101765810810.1073/pnas.1017658108 ↗
59. de Haan LT, Schenning APHJ, Broer DJ (2014) Programmed morphing of liquid crystal networks. Polymer (Guildf) 55:5885–5896. doi: 10.1016/j.polymer.2014.08.02310.1016/j.polymer.2014.08.023 ↗
60. Ware TH, McConney ME, Wie JJ, Tondiglia VP, White TJ (2015) Actuating materials. Voxelated liquid crystal elastomers. Science 347:982–984. doi: 10.1126/science.126101910.1126/science.1261019 ↗
61. Buguin A, Li M-H, Silberzan P, Ladoux B, Keller P (2006) Micro-actuators: when artificial muscles made of nematic liquid crystal elastomers meet soft lithography. J Am Chem Soc 128:1088–1089. doi: 10.1021/ja057507010.1021/ja0575070 ↗
62. Alexander R (1991) Energy-saving mechanisms in walking and running. J Exp Biol 160:55–6910.1242/jeb.160.1.55 ↗
63. Kastelic J, Galeski A, Baer E (1978) The multicomposite structure of tendon. Connect Tissue Res 6:11–23. doi: 10.3109/0300820780915228310.3109/03008207809152283 ↗
64. Fratzl P (2003) Cellulose and collagen: from fibres to tissues. Curr Opin Colloid Interface Sci 8:32–39. doi: 10.1016/S1359-0294(03)00011-610.1016/S1359-0294(03)00011-6 ↗
65. Gatt R, Vella Wood M, Gatt A, Zarb F, Formosa C, Azzopardi KM, Casha A, Agius TP, Schembri-Wismayer P, Attard L, Chockalingam N, Grima JN (2015) Negative Poisson’s ratios in tendons: an unexpected mechanical response. Acta Biomater 24:201–208. doi: 10.1016/j.actbio.2015.06.01810.1016/j.actbio.2015.06.018 ↗
66. Bennett MB, Ker RF, Imery NJ, Alexander RM (1986) Mechanical properties of various mammalian tendons. J Zool 209:537–548. doi: 10.1111/j.1469-7998.1986.tb03609.x10.1111/j.1469-7998.1986.tb03609.x ↗
67. Leng J, Lan X, Liu Y, Du S (2011) Shape-memory polymers and their composites: stimulus methods and applications. Prog Mater Sci 56:1077–1135. doi: 10.1016/j.pmatsci.2011.03.00110.1016/j.pmatsci.2011.03.001 ↗
68. Xiao X, Hu J, Hu J, Zhu Y, Huang H, Lv J, Meng H, Li G, Anis A, Meng H, Zhou X, Mendez J, Zhu Y, Li J, Ma X, Tian H, Xue L, Dai S, Li Z, Jung YC, So HH, Cho JW, Chen S, Hu J, Yuen CW, Chen L, Huang WM, Yang B, An L, Li C, Chan YS, Lu H, Liu Y, Leng J, Du S, Dagnon KL, Huang H, Hu J, Zhu Y, Hu J, Zhu Y, Hu J, Dong ZE, Liu Y, Zimmermann EA, Fratzl P, Barth FG, Dawson C, Vincent JFV, Rocca AM, Elbaum R, Zaltzman L, Burgert I, Fratzl P, Meyers MA, McKittrick J, Chen PY, Fratzl P, Weinkamer R, Liu ZQ, Jiao D, Zhang ZF, Xu W, Ke G, Wu J, Wang X, Barba C, Ackbarow T, Chen X, Keten S, Buehler MJ, Speakman JB, Feughelman M, Feughelman M, Feughelman M, Fraser RDB, MacRae TP, Astbury WT, Street A, Astbury WT, Pauling L, Wortmann FJ, Rigby BJ, Phillips DG, Eaves JD, Schiessel H, Metzler R, Blumen A, Nonnenmacher TF, Williams G, Watts DC, Kumar B, Hu JL, Pan N, Behl M, Razzaq MY, Lendlein A, Lv H, Liu Y, Zhang D, Leng J, Du S, Du H, Zhang J, Liu Y, Kilpeläinen I, Akhtar W, Richard-Lacroix M, Pellerin C, Yao J, Liu Y, Yang S, Liu J, Ishida Y, Chabanne L, Antonietti M, Shalom M, Yan X, Ma M, Guo L, Anderson DG, Langer R, Nagia FA, EL-Mohamedy RSR, Liu C, Qin H, Mather PT (2016) Animal hairs as water-stimulated shape memory materials: mechanism and structural networks in molecular assemblies. Sci Rep 6:26393. doi: 10.1038/srep2639310.1038/srep26393 ↗
69. Liu ZQ, Jiao D, Zhang ZF (2015) Remarkable shape memory effect of a natural biopolymer in aqueous environment. Biomaterials 65:13–21. doi: 10.1016/j.biomaterials.2015.06.03210.1016/j.biomaterials.2015.06.032 ↗
70. Zhao Q, Qi HJ, Xie T (2015) Recent progress in shape memory polymer: new behavior, enabling materials, and mechanistic understanding. Prog Polym Sci 49–50:79–120. doi: 10.1016/j.progpolymsci.2015.04.00110.1016/j.progpolymsci.2015.04.001 ↗
71. Lendlein A, Jiang H, Jünger O, Langer R (2005) Light-induced shape-memory polymers. Nature 434:879–882. doi: 10.1038/nature0349610.1038/nature03496 ↗
72. Kumar UN, Kratz K, Heuchel M, Behl M, Lendlein A (2011) Shape-memory nanocomposites with magnetically adjustable apparent switching temperatures. Adv Mater 23:4157–4162. doi: 10.1002/adma.20110225110.1002/adma.201102251 ↗
73. Wang CC, Huang WM, Ding Z, Zhao Y, Purnawali H (2012) Cooling-/water-responsive shape memory hybrids. Compos Sci Technol 72:1178–1182. doi: 10.1016/j.compscitech.2012.03.02710.1016/j.compscitech.2012.03.027 ↗
74. Rousseau IA (2008) Challenges of shape memory polymers: a review of the progress toward overcoming SMP’s limitations. Polym Eng Sci 48:2075–2089. doi: 10.1002/pen.2121310.1002/pen.21213 ↗
75. Momtaz M, Razavi-Nouri M, Barikani M (2014) Effect of block ratio and strain amplitude on thermal, structural, and shape memory properties of segmented polycaprolactone-based polyurethanes. J Mater Sci 49:7575–7584. doi: 10.1007/s10853-014-8466-y10.1007/s10853-014-8466-y ↗
76. Messori M, Degli Esposti M, Paderni K, Pandini S, Passera S, Riccò T, Toselli M (2012) Chemical and thermomechanical tailoring of the shape memory effect in poly(ε-caprolactone)-based systems. J Mater Sci 48:424–440. doi: 10.1007/s10853-012-6757-810.1007/s10853-012-6757-8 ↗
77. Zhuo H, Hu J, Chen S (2011) Study of the thermal properties of shape memory polyurethane nanofibrous nonwoven. J Mater Sci 46:3464–3469. doi: 10.1007/s10853-011-5251-z10.1007/s10853-011-5251-z ↗
78. Auad ML, Contos VS, Nutt S, Aranguren MI, Marcovich NE (2008) Characterization of nanocellulose- reinforced shape memory polyurethanes. Polym Int 57:651–659. doi: 10.1002/pi.239410.1002/pi.2394 ↗
79. Miaudet P, Derré A, Maugey M, Zakri C, Piccione PM, Inoubli R, Poulin P (2007) Shape and temperature memory of nanocomposites with broadened glass transition. Science 318:1294–1296. doi: 10.1126/science.114559310.1126/science.1145593 ↗
80. Koerner H, Price G, Pearce NA, Alexander M, Vaia RA (2004) Remotely actuated polymer nanocomposites—stress-recovery of carbon-nanotube-filled thermoplastic elastomers. Nat Mater 3:115–120. doi: 10.1038/nmat105910.1038/nmat1059 ↗
81. Nishikawa M, Wakatsuki K, Takeda N (2010) Thermomechanical experiment and analysis on shape recovery properties of shape memory polymer influenced by fiber reinforcement. J Mater Sci 45:3957–3960. doi: 10.1007/s10853-010-4545-x10.1007/s10853-010-4545-x ↗
82. Sun J-Y, Zhao X, Illeperuma WRK, Chaudhuri O, Oh KH, Mooney DJ, Vlassak JJ, Suo Z (2012) Highly stretchable and tough hydrogels. Nature 489:133–136. doi: 10.1038/nature1140910.1038/nature11409 ↗
83. Ratna D, Karger-Kocsis J (2007) Recent advances in shape memory polymers and composites: a review. J Mater Sci 43:254–269. doi: 10.1007/s10853-007-2176-710.1007/s10853-007-2176-7 ↗
84. Hager MD, Bode S, Weber C, Schubert US (2015) Shape memory polymers: past, present and future developments. Prog Polym Sci 49:3–33. doi: 10.1016/j.progpolymsci.2015.04.00210.1016/j.progpolymsci.2015.04.002 ↗
85. Yan X, Wang F, Zheng B, Huang F (2012) Stimuli-responsive supramolecular polymeric materials. Chem Soc Rev 41:6042–6065. doi: 10.1039/c2cs35091b10.1039/c2cs35091b ↗
86. Liu Y, Lv H, Lan X, Leng J, Du S (2009) Review of electro-active shape-memory polymer composite. Compos Sci Technol 69:2064–2068. doi: 10.1016/j.compscitech.2008.08.01610.1016/j.compscitech.2008.08.016 ↗
87. Stahlberg R (2009) The phytomimetic potential of three types of hydration motors that drive nastic plant movements. Mech Mater 41:1162–1171. doi: 10.1016/j.mechmat.2009.05.00310.1016/j.mechmat.2009.05.003 ↗
88. Koller D (1990) Light-driven leaf movements. Plant Cell Environ 13:615–632. doi: 10.1111/j.1365-3040.1990.tb01079.x10.1111/j.1365-3040.1990.tb01079.x ↗
89. Luzar N, Gottsberger G (2001) Flower heliotropism and floral heating of five alpine plant species and the effect on flower visiting in Ranunculus montanus in the Austrian Alps. Arct Antarct Alp Res 33:93–99. doi: 10.2307/155228210.2307/1552282 ↗
90. Schwartz A, Koller D (1978) Phototropic response to vectorial light in leaves of Lavatera cretica L. Plant Physiol 61:924–928. doi: 10.1104/pp.61.6.92410.1104/pp.61.6.924 ↗
91. Whitaker DL, Webster LA, Edwards J (2007) The biomechanics of Cornus canadensis stamens are ideal for catapulting pollen vertically. Funct Ecol 21:219–225. doi: 10.1111/j.1365-2435.2007.01249.x10.1111/j.1365-2435.2007.01249.x ↗
92. Noblin X, Rojas NO, Westbrook J, Llorens C, Argentina M, Dumais J (2012) The fern sporangium: a unique catapult. Science 335:1322–1322. doi: 10.1126/science.121598510.1126/science.1215985 ↗
93. Llorens C, Argentina M, Rojas N, Westbrook J, Dumais J, Noblin X, Skotheim J, Mahadevan L, Dumais J, Forterre Y, Noblin X, Rojas N, Westbrook J, Llorens C, Argentina M, Dumais J, Borno R, Steinmeyer J, Maharbiz M, Martone P, Prantl K, Renner O, Ursprung A, King A, Ritman K, Milburn J, Haider K, Steudle E, Caupin F, Herbert E, Skotheim J, Mahadevan L, Epstein P, Plesset M (2016) The fern cavitation catapult: mechanism and design principles. J R Soc Interface 13:20150930. doi: 10.1098/rsif.2015.093010.1098/rsif.2015.0930 ↗
94. Forterre Y, Skotheim JM, Dumais J, Mahadevan L (2005) How the venus flytrap snaps. Nature 433:421–425. doi: 10.1038/nature0318510.1038/nature03185 ↗
95. Burgert I, Fratzl P (2009) Actuation systems in plants as prototypes for bioinspired devices. Philos Trans A 367:1541–1557. doi: 10.1098/rsta.2009.000310.1098/rsta.2009.0003 ↗
96. Zwieniecki MA, Melcher PJ, Michele Holbrook NM (2001) Hydrogel control of xylem hydraulic resistance in plants. Science 291:1059–1062. doi: 10.1126/science.105717510.1126/science.1057175 ↗
97. Guan Y, Zhang Y (2011) PNIPAM microgels for biomedical applications: from dispersed particles to 3D assemblies. Soft Matter 7:6375–6384. doi: 10.1039/c0sm01541e10.1039/c0sm01541e ↗
98. Guvendiren M, Lu HD, Burdick JA (2012) Shear-thinning hydrogels for biomedical applications. Soft Matter 8:260–272. doi: 10.1039/C1SM06513K10.1039/C1SM06513K ↗
99. Martin BD, Linhardt RJ, Dordick JS (1998) Highly swelling hydrogels from ordered galactose-based polyacrylates. Biomaterials 19:69–76. doi: 10.1016/S0142-9612(97)00184-110.1016/S0142-9612(97)00184-1 ↗
100. Osada Y, Matsuda A (1995) Shape memory in hydrogels. Nature 376:219. doi: 10.1038/376219a010.1038/376219a0 ↗