SCIENTIA SINICA Informationis, Volume 48, Issue 6: 650-669(2018) https://doi.org/10.1360/N112018-00117

Recent advances in flexible self-healing materials and sensors

More info
  • ReceivedMay 7, 2018
  • AcceptedMay 18, 2018
  • PublishedJun 12, 2018


Endowing devices with the self-healing capacity is an effective approach to enhance their reliability, durability, and functionality, especially for flexible electronic materials and devices. This article reviews the developments in the field of flexible self-healing materials and sensors. This review first introduces the self-healing mechanism of intrinsic and extrinsic polymers, and the advances in self-healing flexible conductive materials are discussed briefly. Then, the fabrication techniques, sensing performance, and healing performance of the newly developed flexible self-healing sensors, especially the flexible self-healing force sensors, are described in detail. Finally, the existing challenges and some possible solutions for flexible self-healing materials and sensors are discussed.

Funded by





[1] Someya T, Bao Z N, Malliaras G G. The rise of plastic bioelectronics. Nature, 2016, 540: 379-385 CrossRef PubMed ADS Google Scholar

[2] Kim D H, Ghaffari R, Lu N. Flexible and stretchable electronics for biointegrated devices. Annu Rev Biomed Eng, 2012, 14: 113-128 CrossRef PubMed Google Scholar

[3] Amjadi M, Kyung K U, Park I. Stretchable, skin-mountable, and wearable strain sensors and their potential applications: a review. Adv Funct Mater, 2016, 26: 1678-1698 CrossRef Google Scholar

[4] Trung T Q, Lee N E. Flexible and stretchable physical sensor integrated platforms for wearable human-activity monitoringand personal healthcare. Adv Mater, 2016, 28: 4338-4372 CrossRef PubMed Google Scholar

[5] Wang X W, Liu Z, Zhang T. Flexible sensing electronics for wearable/attachable health monitoring. Small, 2017, 13: 1602790 CrossRef PubMed Google Scholar

[6] Yang T T, Xie D, Li Z H. Recent advances in wearable tactile sensors: Materials, sensing mechanisms, and device performance. Mater Sci Eng-R-Rep, 2017, 115: 1-37 CrossRef Google Scholar

[7] Li Q, Zhang L N, Tao X M. Review of flexible temperature sensing networks for wearable physiological monitoring. Adv Healthcare Mater, 2017, 6: 1601371 CrossRef PubMed Google Scholar

[8] Wu H, Huang Y A, Xu F. Energy harvesters for wearable and stretchable electronics: from flexibility to stretchability. Adv Mater, 2016, 28: 9881-9919 CrossRef PubMed Google Scholar

[9] Dubal D P, Chodankar N R, Kim D H. Towards flexible solid-state supercapacitors for smart and wearable electronics.. Chem Soc Rev, 2018, 47: 2065-2129 CrossRef PubMed Google Scholar

[10] Ahner J, Bode S, Micheel M, et al. Self-healing functional polymeric materials. Adv Polym Sci, 2016, 273: 247--283. Google Scholar

[11] Zhang L, Chandran B K, Chen X D. Self-healing electronic nanodevices. In: Soft Matter Nanotechnology: From Structure to Function. Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA, 2015. 401--416. Google Scholar

[12] Luo C S, Wan P, Yang H. Healable transparent electronic devices. Adv Funct Mater, 2017, 27: 1606339 CrossRef Google Scholar

[13] Yang Y, Zhu B, Yin D. Flexible self-healing nanocomposites for recoverable motion sensor. Nano Energy, 2015, 17: 1-9 CrossRef Google Scholar

[14] Tee B C K, Wang C, Allen R. An electrically and mechanically self-healing composite with pressure- and flexion-sensitive properties for electronic skin applications. Nat Nanotech, 2012, 7: 825-832 CrossRef PubMed ADS Google Scholar

[15] Darabi M A, Khosrozadeh A, Mbeleck R, et al. Skin-inspired multifunctional autonomic-intrinsic conductive self-healing hydrogels with pressure sensitivity, stretchability, and 3D printability. Adv Mater, 2018, 30: 1700533. Google Scholar

[16] Bergman S D, Wudl F. Mendable polymers. J Mater Chem, 2008, 18: 41-62 CrossRef Google Scholar

[17] Wool R P. Self-healing materials: a review. Soft Matter, 2008, 4: 400-418 CrossRef ADS Google Scholar

[18] Wu D Y, Meure S, Solomon D. Self-healing polymeric materials: a review of recent developments. Prog Polymer Sci, 2008, 33: 479-522 CrossRef Google Scholar

[19] Li Y, Chen S S, Wu M C. Polyelectrolyte multilayers impart healability to highly electrically conductive films. Adv Mater, 2012, 24: 4578-4582 CrossRef PubMed Google Scholar

[20] Gong C K, Liang J J, Hu W. A healable, semitransparent silver nanowire-polymer composite conductor. Adv Mater, 2013, 25: 4186-4191 CrossRef PubMed Google Scholar

[21] Bai S L, Sun C Z, Yan H. Healable, transparent, room-temperature electronic sensors based on carbon nanotube network-coated polyelectrolyte multilayers. Small, 2015, 11: 5807-5813 CrossRef PubMed Google Scholar

[22] Huynh T P, Haick H. Self-healing, fully functional, and multiparametric flexible sensing platform. Adv Mater, 2016, 28: 138-143 CrossRef PubMed Google Scholar

[23] Lee D H, Heo G, Pyo K H. Mechanically robust and healable transparent electrode fabricated via vapor-assisted solution process. ACS Appl Mater Interfaces, 2016, 8: 8129-8136 CrossRef Google Scholar

[24] Pyo K H, Lee D H, Kim Y, et al. Extremely rapid and simple healing of a transparent conductor based on Ag nanowires and polyurethane with a diels-alder network. J Mater Chem, 2016, 4: 972--977. Google Scholar

[25] Hou C Y, Huang T, Wang H Z. A strong and stretchable self-healing film with self-activated pressure sensitivity for potential artificial skin applications. Sci Rep, 2013, 3: 3138 CrossRef PubMed ADS Google Scholar

[26] D'Elia E, Barg S, Ni N. Self-healing graphene-based composites with sensing capabilities. Adv Mater, 2015, 27: 4788-4794 CrossRef PubMed Google Scholar

[27] Guo K, Zhang D L, Zhang X M. Conductive elastomers with autonomic self-healing properties. Angew Chem Int Ed, 2015, 54: 12127-12133 CrossRef PubMed Google Scholar

[28] Zhang D L, Ju X, Li L H. An efficient multiple healing conductive composite via host-guest inclusion.. Chem Commun, 2015, 51: 6377-6380 CrossRef PubMed Google Scholar

[29] Williams K A, Boydston A J, Bielawski C W. Towards electrically conductive, self-healing materials. J R Soc Interface, 2007, 4: 359-362 CrossRef PubMed Google Scholar

[30] Aboudzadeh M A, Mu {n}oz M E, Santamar\'{\i}a A. Facile synthesis of supramolecular ionic polymers that combine unique rheological, ionic conductivity, and self-healing properties. Macromol Rapid Commun, 2012, 33: 314-318 CrossRef Google Scholar

[31] Feldner T, Haring M, Saha S. Supramolecular metallogel that imparts self-healing properties to other gel networks. Chem Mater, 2016, 28: 3210-3217 CrossRef Google Scholar

[32] Chen D, Wang D, Yang Y. Self-healing materials for next-generation energy harvesting and storage devices. Adv Energy Mater, 2017, 7: 1700890 CrossRef Google Scholar

[33] Blaiszik B J, Kramer S L B, Olugebefola S C. Self-healing polymers and composites. Annu Rev Mater Res, 2010, 40: 179-211 CrossRef ADS Google Scholar

[34] Chen X X. A thermally re-mendable cross-linked polymeric material. Science, 2002, 295: 1698-1702 CrossRef PubMed ADS Google Scholar

[35] Chen X X, Wudl F, Mal A K. New thermally remendable highly cross-linked polymeric materials. Macromolecules, 2003, 36: 1802-1807 CrossRef ADS Google Scholar

[36] Murphy E B, Bolanos E, Schaffner-Hamann C. Synthesis and characterization of a single-component thermally remendable polymer network: staudinger and stille revisited. Macromolecules, 2008, 41: 5203-5209 CrossRef ADS Google Scholar

[37] Park J S, Takahashi K, Guo Z H. Towards development of a self-healing composite using a mendable polymer and resistive heating. J Composite Mater, 2008, 42: 2869-2881 CrossRef Google Scholar

[38] Park J S, Kim H S, Thomas Hahn H. Healing behavior of a matrix crack on a carbon fiber/mendomer composite. Composites Sci Tech, 2009, 69: 1082-1087 CrossRef Google Scholar

[39] Peterson A M, Jensen R E, Palmese G R. Reversibly cross-linked polymer gels as healing agents for epoxy-amine thermosets. ACS Appl Mater Interfaces, 2009, 1: 992-995 CrossRef PubMed Google Scholar

[40] Otsuka H, Nagano S, Kobashi Y. A dynamic covalent polymer driven by disulfide metathesis under photoirradiation. Chem Commun, 2010, 46: 1150-1152 CrossRef PubMed Google Scholar

[41] Canadell J, Goossens H, Klumperman B. Self-healing materials based on disulfide links. Macromolecules, 2011, 44: 2536-2541 CrossRef ADS Google Scholar

[42] Amamoto Y, Otsuka H, Takahara A. Self-healing of covalently cross-linked polymers by reshuffling thiuram disulfide moieties in air under visible light. Adv Mater, 2012, 24: 3975-3980 CrossRef PubMed Google Scholar

[43] Deng G H, Tang C M, Li F Y. Covalent cross-linked polymer gels with reversible sol-gel transition and self-healing properties. Macromolecules, 2010, 43: 1191-1194 CrossRef ADS Google Scholar

[44] Kuhl N, Bode S, Bose R K. Acylhydrazones as reversible covalent crosslinkers for self-healing polymers. Adv Funct Mater, 2015, 25: 3295-3301 CrossRef Google Scholar

[45] Whiteley J M, Taynton P, Zhang W. Ultra-thin solid-state li-ion electrolyte membrane facilitated by a self-healing polymer matrix. Adv Mater, 2015, 27: 6922-6927 CrossRef PubMed Google Scholar

[46] Taynton P, Ni H G, Zhu C P. Repairable woven carbon fiber composites with full recyclability enabled by malleable polyimine networks. Adv Mater, 2016, 28: 2904-2909 CrossRef PubMed Google Scholar

[47] Lu Y X, Guan Z B. Olefin metathesis for effective polymer healing via dynamic exchange of strong carbon-carbon double bonds. J Am Chem Soc, 2012, 134: 14226-14231 CrossRef PubMed Google Scholar

[48] Campanella A, Dohler D, Binder W H. Self-healing in supramolecular polymers. Macromol Rapid Commun, 2018: 1700739. Google Scholar

[49] Herbst F, Dohler D, Michael P. Self-healing polymers via supramolecular forces.. Macromol Rapid Commun, 2013, 34: 203-220 CrossRef PubMed Google Scholar

[50] Cordier P, Tournilhac F, Soulié-Ziakovic C. Self-healing and thermoreversible rubber from supramolecular assembly. Nature, 2008, 451: 977-980 CrossRef PubMed ADS Google Scholar

[51] Montarnal D, Tournilhac F, Hidalgo M. Versatile one-pot synthesis of supramolecular plastics and self-healing rubbers.. J Am Chem Soc, 2009, 131: 7966-7967 CrossRef PubMed Google Scholar

[52] Yang L, Lin Y L, Wang L S. The synthesis and characterization of supramolecular elastomers based on linear carboxyl-terminated polydimethylsiloxane oligomers. Polym Chem, 2014, 5: 153-160 CrossRef Google Scholar

[53] Zhang A Q, Yang L, Lin Y L. Self-healing supramolecular elastomers based on the multi-hydrogen bonding of low-molecular polydimethylsiloxanes: synthesis and characterization. J Appl Polym Sci, 2013, 129: 2435-2442 CrossRef Google Scholar

[54] Maes F, Montarnal D, Cantournet S. Activation and deactivation of self-healing in supramolecular rubbers. Soft Matter, 2012, 8: 1681-1687 CrossRef ADS Google Scholar

[55] White S R, Sottos N R, Geubelle P H. Autonomic healing of polymer composites. Nature, 2001, 409: 794-797 CrossRef PubMed Google Scholar

[56] Rule J D, Brown E N, Sottos N R. Wax-protected catalyst microspheres for efficient self-healing materials. Adv Mater, 2005, 17: 205-208 CrossRef Google Scholar

[57] Jackson A C, Bartelt J A, Marczewski K. Silica-protected micron and sub-micron capsules and particles for self-healing at the microscale. Macromol Rapid Commun, 2011, 32: 82-87 CrossRef PubMed Google Scholar

[58] Yuan Y C, Rong M Z, Zhang M Q. Study of factors related to performance improvement of self-healing epoxy based on dual encapsulated healant. Polymer, 2009, 50: 5771-5781 CrossRef Google Scholar

[59] Cho S H, Andersson H M, White S R. Polydimethylsiloxane-based self-healing materials. Adv Mater, 2006, 18: 997-1000 CrossRef Google Scholar

[60] Caruso M M, Delafuente D A, Ho V. Solvent-promoted self-healing epoxy materials. Macromolecules, 2007, 40: 8830-8832 CrossRef ADS Google Scholar

[61] Yang J L, Keller M W, Moore J S. Microencapsulation of isocyanates for self-healing polymers. Macromolecules, 2008, 41: 9650-9655 CrossRef ADS Google Scholar

[62] Bleay S M, Loader C B, Hawyes V J. A smart repair system for polymer matrix composites. Composites Part A-Appl Sci Manufacturing, 2001, 32: 1767-1776 CrossRef Google Scholar

[63] Pang J W C, Bond I P. A hollow fibre reinforced polymer composite encompassing self-healing and enhanced damage visibility. Composites Sci Tech, 2005, 65: 1791-1799 CrossRef Google Scholar

[64] Williams H R, Trask R S, Bond I P. Self-healing composite sandwich structures. Smart Mater Struct, 2007, 16: 1198-1207 CrossRef ADS Google Scholar

[65] Toohey K S, Sottos N R, Lewis J A. Self-healing materials with microvascular networks. Nat Mater, 2007, 6: 581-585 CrossRef PubMed Google Scholar

[66] So J H, Thelen J, Qusba A. Reversibly deformable and mechanically tunable fluidic antennas. Adv Funct Mater, 2009, 19: 3632-3637 CrossRef Google Scholar

[67] Blaiszik B J, Kramer S L B, Grady M E. Autonomic restoration of electrical conductivity. Adv Mater, 2012, 24: 398-401 CrossRef PubMed Google Scholar

[68] Odom S A, Chayanupatkul S, Blaiszik B J. A self-healing conductive ink. Adv Mater, 2012, 24: 2578-2581 CrossRef PubMed Google Scholar

[69] Kang S, Jones A R, Moore J S. Microencapsulated carbon black suspensions for restoration of electrical conductivity. Adv Funct Mater, 2014, 24: 2947-2956 CrossRef Google Scholar

[70] Caruso M M, Schelkopf S R, Jackson A C. Microcapsules containing suspensions of carbon nanotubes. J Mater Chem, 2009, 19: 6093-6096 CrossRef Google Scholar

[71] Sun H, You X, Jiang Y. Self-healable electrically conducting wires for wearable microelectronics.. Angew Chem Int Ed, 2014, 53: 9526-9531 CrossRef PubMed Google Scholar

[72] Zhang X Y, Tang Z, Tian D. A self-healing flexible transparent conductor made of copper nanowires and polyurethane. Mater Res Bull, 2017, 90: 175-181 CrossRef Google Scholar

[73] Sun J Y, Keplinger C, Whitesides G M. Ionic skin. Adv Mater, 2014, 26: 7608-7614 CrossRef PubMed Google Scholar

[74] Kim C C, Lee H H, Oh K H. Highly stretchable, transparent ionic touch panel. Science, 2016, 353: 682-687 CrossRef PubMed ADS Google Scholar

[75] Wang J, Liu F, Tao F. Rationally Designed Self-Healing Hydrogel Electrolyte toward a Smart and Sustainable Supercapacitor. ACS Appl Mater Interfaces, 2017, 9: 27745-27753 CrossRef Google Scholar

[76] Cheng X, Pan J, Zhao Y. Gel polymer electrolytes for electrochemical energy storage. Adv Energy Mater, 2018, 8: 1702184 CrossRef Google Scholar

[77] Guo Y, Zheng K, Wan P. A flexible stretchable hydrogel electrolyte for healable all-in-one configured supercapacitors. Small, 2018, 14: 1704497 CrossRef PubMed Google Scholar

[78] Cai G, Wang J, Qian K. Extremely stretchable strain sensors based on conductive self-healing dynamic cross-links hydrogels for human-motion detection. Adv Sci, 2017, 4: 1600190 CrossRef PubMed Google Scholar

[79] Liu S, Lin Y, Wei Y. A high performance self-healing strain sensor with synergetic networks of poly($\varepsilon$-caprolactone) microspheres, graphene and silver nanowires. Composites Sci Tech, 2017, 146: 110-118 CrossRef Google Scholar

[80] Han Y Y, Wu X D, Zhang X X. Self-healing, highly sensitive electronic sensors enabled by metal-ligand coordination and hierarchical structure design. ACS Appl Mater Interfaces, 2017, 9: 20106-20114 CrossRef Google Scholar

[81] Liu X, Lu C, Wu X. Self-healing strain sensors based on nanostructured supramolecular conductive elastomers. J Mater Chem A, 2017, 5: 9824-9832 CrossRef Google Scholar

[82] Cao J, Zhang X, Lu C. Self-healing sensors based on dual noncovalent network elastomer for human motion monitoring. Macromol Rapid Commun, 2017, 38: 1700406 CrossRef PubMed Google Scholar

[83] Cao J, Lu C, Zhuang J. Multiple Hydrogen Bonding Enables the Self-Healing of Sensors for Human-Machine Interactions.. Angew Chem Int Ed, 2017, 56: 8795-8800 CrossRef PubMed Google Scholar

[84] Hou J, Liu M, Zhang H. Healable green hydrogen bonded networks for circuit repair, wearable sensor and flexible electronic devices. J Mater Chem A, 2017, 5: 13138-13144 CrossRef Google Scholar

[85] Rong Q, Lei W, Chen L. Anti-freezing, conductive self-healing organohydrogels with stable strain-sensitivity at subzero temperatures. Angew Chem Int Ed, 2017, 56: 14159-14163 CrossRef PubMed Google Scholar

[86] Liu Y J, Cao W T, Ma M G. Ultrasensitive wearable soft strain sensors of conductive, self-healing, and elastic hydrogels with synergistic “soft and hard" hybrid networks. ACS Appl Mater Interfaces, 2017, 9: 25559-25570 CrossRef Google Scholar

[87] Liu S, Li L. Ultrastretchable and self-healing double-network hydrogel for 3d printing and strain sensor. ACS Appl Mater Interfaces, 2017, 9: 26429-26437 CrossRef Google Scholar

[88] Liu S, Li K, Hussain I. A Conductive Self-Healing Double Network Hydrogel with Toughness and Force Sensitivity.. Chem Eur J, 2018, 24: 6632-6638 CrossRef PubMed Google Scholar

[89] Wang T, Zhang Y, Liu Q. A self-healable, highly stretchable, and solution processable conductive polymer composite for ultrasensitive strain and pressure sensing. Adv Funct Mater, 2018, 28: 1705551 CrossRef Google Scholar

[90] Li J, Liu Q, Ho D. Three-dimensional graphene structure for healable flexible electronics based on diels-alder chemistry. ACS Appl Mater Interfaces, 2018, 10: 9727-9735 CrossRef Google Scholar

[91] Yang H, Qi D, Liu Z. Soft thermal sensor with mechanical adaptability. Adv Mater, 2016, 28: 9175-9181 CrossRef PubMed Google Scholar

[92] Zhang Q, Liu L, Pan C. Thermally sensitive, adhesive, injectable, multiwalled carbon nanotube covalently reinforced polymer conductors with self-healing capabilities. J Mater Chem C, 2018, 6: 1746-1752 CrossRef Google Scholar

[93] Fowler J D, Allen M J, Tung V C. Practical chemical sensors from chemically derived graphene. ACS Nano, 2009, 3: 301-306 CrossRef PubMed Google Scholar

[94] Wang S, Xu L P, Zhang X. Ultrasensitive electrochemical biosensor based on noble metal nanomaterials. Sci Adv Mater, 2015, 7: 2084-2102 CrossRef Google Scholar

[95] Bandodkar A J, Jeerapan I, Wang J. Wearable chemical sensors: present challenges and future prospects. ACS Sens, 2016, 1: 464-482 CrossRef Google Scholar

[96] Gao W, Emaminejad S, Nyein H Y Y. Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis. Nature, 2016, 529: 509-514 CrossRef PubMed ADS Google Scholar

[97] Huang W, Besar K, Zhang Y. A high-capacitance salt-free dielectric for self-healable, printable, and flexible organic field effect transistors and chemical sensor. Adv Funct Mater, 2015, 25: 3745-3755 CrossRef PubMed Google Scholar

[98] Jin H, Huynh T P, Haick H. Self-healable sensors based nanoparticles for detecting physiological markers via skin and breath: toward disease prevention via wearable devices. Nano Lett, 2016, 16: 4194-4202 CrossRef PubMed ADS Google Scholar

[99] Huynh T P, Khatib M, Srour R. Composites of polymer and carbon nanostructures for self-healing chemical sensors. Adv Mater Technol, 2016, 1: 1600187 CrossRef Google Scholar

[100] Fan Z, Ho J C, Takahashi T. Toward the development of printable nanowire electronics and sensors. Adv Mater, 2009, 21: 3730-3743 CrossRef Google Scholar

[101] Fukuda K, Takeda Y, Yoshimura Y. Fully-printed high-performance organic thin-film transistors and circuitry on one-micron-thick polymer films. Nat Commun, 2014, 5: 4147 CrossRef PubMed ADS Google Scholar

[102] Lu C C, Lin Y C, Yeh C H. High mobility flexible graphene field-effect transistors with self-healing gate dielectrics. ACS Nano, 2012, 6: 4469-4474 CrossRef PubMed Google Scholar

[103] Ko J, Kim Y J, Kim Y S. Self-healing polymer dielectric for a high capacitance gate insulator. ACS Appl Mater Interfaces, 2016, 8: 23854-23861 CrossRef Google Scholar

[104] Bauer S. Flexible electronics: Sophisticated skin. Nat Mater, 2013, 12: 871-872 CrossRef PubMed ADS Google Scholar

[105] Choi S, Lee H, Ghaffari R. Recent advances in flexible and stretchable bio-electronic devices integrated with nanomaterials. Adv Mater, 2016, 28: 4203-4218 CrossRef PubMed Google Scholar

[106] Hammock M L, Chortos A, Tee B C K. 25th anniversary article: The evolution of electronic skin (e-skin): a brief history, design considerations, and recent progress. Adv Mater, 2013, 25: 5997-6038 CrossRef PubMed Google Scholar

[107] Kim D H, Lu N, Ma R. Epidermal electronics. Science, 2011, 333: 838-843 CrossRef PubMed ADS Google Scholar

[108] Kuang X, Chen K, Dunn C K. 3D printing of highly stretchable, shape-memory, and self-healing elastomer toward novel 4D printing. ACS Appl Mater Interfaces, 2018, 10: 7381-7388 CrossRef Google Scholar

[109] Yu Y, Liu F, Zhang R. Suspension 3D printing of liquid metal into self-healing hydrogel. Adv Mater Technol, 2017, 2: 1700173 CrossRef Google Scholar

  • Figure 1

    (Color online) Schematic of self-healing mechanism of polymers [32]@Copyright 2017 John Wiley and Sons. protectłinebreak(a) Intrinsic; (b) extrinsic

  • Figure 2

    (Color online) Schematic of self-healing of conductive material/polymer composites: (a) Schematic of self-healing via embedding liquid conductive materials capsules [67]@Copyright 2011 John Wiley and Sons. (b) Schematic of self-healing of AgNWs/(bPEI/PAA-HA) composite with the aid of water [19]@Copyright 2012 John Wiley and Sons. (c) Schematic of the microstructure of $\mu$Ni/L composite and the process of electrical self-healing. 1. Undamaged material; 2. completely fractured material; 3. Self-supporting material with its fractured surfaces contact for 15 s; 4. Flexed material after being healed for 5 min, showing its mechanical strength and flexibility [14]@Copyright 2012 Springer Nature

  • Figure 3

    (Color online) Self-healing piezoresistive force sensor based on $\mu$Ni/L composite [14]@Copyright 2012 Springer Nature. (a) Current-voltage curve of a commercial LED using self-healing $\mu$Ni/L composite as conducting wire. Inset: optical photograph of the circuit taken at 2.5 V (scale bar, 10 mm). (b) and (c) Self-healing of the (b) electrical and (c) mechanicalperformance of $\mu$Ni/L composite. (d) Electrical response of the flexion sensors based on $\mu$Ni/L composite in free-standing modes and self-adhered modes on PET substrate. (e) Electrical response of the parallel-plate structured tactile sensor based on $\mu$Ni/L composite. (f) Self-healing flexion and tactile sensor circuit schematic and the optical photograph of a fully articulated wooden mannequin with its elbow and palm region mounted with the flexion and tactile sensor circuits

  • Figure 4

    (Color online) Real-time monitoring of human motions using the superelastic strain sensor based on self-healing SWNT/PVA-borax hydrogel composite [78]. (a) Bending and release of the finger; (b) bending of the knee; (c) bending and release of the neck; (d) bending and release of the elbow

  • Figure 5

    (Color online) Self-healing piezoresistive stress/strain sensor based on conductive polymer [15]@Copyright 2017 John Wiley and Sons. (a) Schematic of the self-healing mechanism; (b) self-healing efficiency of mechanical property; protectłinebreak(c) electrical self-healing property; (d) schematic of the preparation of wearable sensor via 3D printing technique; protectłinebreak (e) real-time human motion monitoring system based on the wearable sensor and smart phone

  • Figure 6

    (Color online) SWNT/L composite [91]@Copyright 2016 John Wiley and Sons. (a) Schematic of the structure; (b) and (c) optical photographs; (d) and (e) temperature sensing performance and the optical photographs showing the measurement procedure; (f) electrical self-healing performance

  • Figure 7

    (Color online) Self-healable flexible gas sensor based on MWNT/PEM composite film [21]@Copyright 2015 John Wiley and Sons. (a) Schematic showing the self-healing procedure of the gas sensor; (b)–(e) SEM images of MWNT/PEM film with a cut before and after being healed; (f) electrical self-healing property; (g) the sensing sensitivity of MWNT/PEM film to 25 ppm ${\rm~NH}_{3}$ after healing for different times

  • Figure 8

    (Color online) Self-healing flexible multifunctional sensor [22]@Copyright 2015 John Wiley and Sons. protectłinebreak(a) Schematic of the device structure and its optical photograph; SEM images of the microstructure of (b1)–(b4) PU substrate, (c1)–(c4) PU/$\mu$Ag composite, and (d1)–(d4) AuNP film with a cut showing the self-healing procedure; (e) electrical response to bending deformation; (f) electrical response to stretching deformation; (g) electrical response to VOC n-octanol; (h) electrical response to temperature variation

  • Figure 9

    (Color online) The overall experimental strategy relating to the flexible self-healable multifunctional sensor for human health monitoring application [98]@Copyright 2016 American Chemical Society. (a) Schematic of the structure; protectłinebreak(b) schematic of the molecular structure used for the functionalization of AuNP; (c) demonstration of the self-heal of the sensor under 3 different damage modes

  • Table 1   Summary of the self-healing performance of typical polymers $^{\rm~a)}$
    Material Mechanical Healing Healing Healing Ref.
    strength mechanism condition efficiency (%
    3M4F 121 MPa/ Thermal reversible 120${^\circ}$C$\sim$150${^\circ}$C 41$\sim$50 [34]
    Compression DA reaction (N$_{2})$/2 h$~\to~$RT
    2MEP4F 121 MPa/ Thermal reversible 115${^\circ}$C/30 min 80 [35]
    Compression DA reaction $\to~$40${^\circ}$C/6 h
    DCPD based 85 MPa/par Compression Thermal reversible 120${^\circ}$C(Ar)/20 h 46 [36]
    polymer DA reaction
    Epoxy based par rubber 0.5 MPa/par Stretch Disulfide bond 60${^\circ}$C/1 h 95 [41]
    PU rubber 3.9 MPa/par Stretch Disulfide bond Visible light/ 24 h 97 [42]
    Ru/PBD 0.4 MPa/par Stretch C-C double bond 20 kPa/1 h 100 [47]
    CF/polyimine 140 MPa/par Bending Imine bond 121${^\circ}$C/45 MPa 100 [46]
    M1-TEGMEMA Acylhydrazone bond 100${^\circ}$C/24 h 100 [44]
    Fatty acid based SR 2 MPa/par Stretch Hydrogen bond RT/3 h 100 [50]
    PDMS-COOH$_{2}$ par based SR 0.4 MPa/par Stretch Hydrogen bond 80${^\circ}$C/16 h 100 [53]

    a) 3M (maleimide monomor); 4F (furan monomer); RT (room temperature); 2MEP (1, 8-Bis(maleimido)-1-ethylpropane); DCPD (dicyclopentadiene); PU (polyurethane); PBD (polybutadiene); CF (carbon fiber); M1 (acylhydrazone monomer); TEGMEMA (triethylene glycol methylether methacrylate); SR (supermolecular rubber); PDMS (polydimethylsiloxane oligomers); COOH (carboxyl)

  • Table 2   Summary of typical research about flexible self-healing sensors$^{\rm~a)}$
    Material Healing par mechanism Healing condition/par efficiency Application Ref.
    MDPB-TDF/ S-CCTO Self-healing of SWNT 105${^\circ}$C/30 min: Capacitive [13]
    driven by thermal electrical$\sim~$89%; force sensor
    reversible DA reaction mechanical$\sim~$86%
    $\mu~$Ni/L Hydrogen bond 50 kPa/15 s: electrical$\sim~$90% Piezoresistive [14]
    50${^\circ}$C/10 min: mechanical$\sim~$100% force sensor
    rGO/PBS B-O dative bond & RT/10 min: par electrical$\sim~$90%; Piezoresistive [26]
    hydrogen bond mechanical$\sim~$80% force sensor
    SWNT/ PVA-borax Hydrogen bond RT/3.2 s: electrical$\sim~$98% Piezoresistive [78]
    force sensor
    m-PCL/GO/ AgNWs Hydrogen bond 80${^\circ}$C/3 min: par electrical$\sim~$80%; Piezoresistive [79]
    mechanical$\sim~$100% force sensor
    CNT-Fe$^{3~+~}$/PDA@ENR Metal coordination bond RT/24 h: par electrical$\sim~$100%; Piezoresistive [80]
    mechanical$\sim~$89.3% force sensor
    CNTs@(PEI@CNC)/ Hydrogen bond Hot-press: par electrical$\sim~$100%; piezoresistive [81]
    XNBR mechanical$\sim~$83% force sensor
    C-CNC@GA@Ca$^{2+}$ Hydrogen & RT/30 s: par electrical$\sim~$100%; Piezoresistive [82]
    @CNTs/ENR metal coordination bond mechanical$\sim~$90% force sensor
    C-CNC@CT@CNTs/ENR Hydrogen bond RT/15 s: par electrical$\sim~$100%; Piezoresistive par [83]
    mechanical$\sim~$100% force sensor
    Amylopectin par hydrogel Hydrogen bond RT/3 s: electrical$\sim~$99.3%; Piezoresistive [84]
    RT/5 min: mechanical$\sim~$98.4% force sensor
    PVA-PEDOT: PSS Hydrogen bond 80${^\circ}$C $\to~-$20${^\circ}$C: par electrical$\sim~$100%; Piezoresistive [85]
    mechanical$\sim~$85% force sensor
    PVA-PVP/CNC-Fe$^{3~+~}$ Ionic coordination bond RT/5 min: par electrical$\sim~$100%; Piezoresistive [86]
    mechanical$\sim~$100% force sensor
    $\kappa~$-carrageenan/PAAm Thermal-reversibleg 90${^\circ}$C/20 min: par electrical$\sim~$99.2%; Piezoresistive [87]
    $\kappa~$-carrageenan mechanical$\sim~$100% force sensor
    PEG-PAA Metal coordination & RT/2 h: electrical $\sim~$100% par RT/12 h: Piezoresistive [88]
    Hydrogen bond mechanical$\sim~$96.8% force sensor
    PANI-PAA-PA Hydrogen bond & Slight pressure/24 h: electrical$\sim~$99%; Piezoresistive [89]
    electrostatic interaction mechanical$\sim~$99% force sensor
    Graphene/PU Thermal reversible Microwave/5 min$~\to~$65${^\circ}$C/5 h: par Piezoresistive [90]
    DA reaction electrical$\sim~$75%; mechanical$\sim~$100% force sensor
    PAA-Fe$^{3~+~}$/DCh-PPy Ionic interaction RT/1 min: electrical$\sim~$96% par Piezoresistive [15]
    RT/2 min: mechanical$\sim~$100% force sensor
    PDMAA-PVA/rGO Hydrogen bond RT/12 h: par electrical$\sim~$89.6%; Piezoresistive [25]
    mechanical$\sim~$100% force sensor
    SWNT/L Hydrogen bond RT/1 h: electrical$\sim~$100% Temperature sensor [91]
    P(BMA-co-LMA)/MWNT C-C double cond 60${^\circ}$C/3 h: par electrical$\sim~$98%; Temperature sensor [92]
    MWNT/PEM Hydrogen bond & Water/30 min: par electrical $\sim~$91%; Gas sensor [21]
    electrostatic interaction mechanical$\sim~$100%

    a) S-CCTO (surface-modified CaCu3Ti4O12); MDPB (1, 1'-(methylene di-4, 1-phenylene) bismaleimide); TDF (2, 2'-(Thiodimethylene) difuran); PBS (polyborosiloxane); PVA (polyvinyl alcohol); m-PCL (poly( 3-caprolactone) microspheres); PDA (polydopamine); ENR (epoxidized natural rubber); PEI (polyethyleneimine); C-CNC (carboxyl cellulose nanocrystals); XNBR (carboxylated nitrile rubber); GA (gelatin); CT (chitosan); PEDOT:PSS (poly(3, 4-ethylenedioxythiophene):polystryrene sulfonate); PVP (polyvinyl pyrrolidone); PAAm (polyacrylamide); PEG (polyethylene glycol); PAA (poly(acrylic acid)); PANI (polyaniline); PA (phytic acid); DCh (double-bond decorated chitosan); PPy (polypyrrole); PDMAA (poly(N, N-dimethylacrylamide)); P(BMA-co-LMA) (poly(butyl methacrylate-co-lauryl methacrylate)); PEM (polyelectrolyte multilayer)

Copyright 2020 Science China Press Co., Ltd. 《中国科学》杂志社有限责任公司 版权所有