Stretchable electronics find widespread uses in a variety of applications such as wearable electronics, on-skin electronics, soft robotics and bioelectronics. Stretchable electronic devices conventionally built with elastomeric thin films show a lack of permeability, which not only impedes wearing comfort and creates skin inflammation over long-term wearing but also limits the design form factors of device integration in the vertical direction. Here, we report a stretchable conductor that is fabricated by simply coating or printing liquid metal onto an electrospun elastomeric fibre mat. We call this stretchable conductor a liquid-metal fibre mat. Liquid metal hanging among the elastomeric fibres self-organizes into a laterally mesh-like and vertically buckled structure, which offers simultaneously high permeability, stretchability, conductivity and electrical stability. Furthermore, the liquid-metal fibre mat shows good biocompatibility and smart adaptiveness to omnidirectional stretching over 1,800% strain. We demonstrate the use of a liquid-metal fibre mat as a building block to realize highly permeable, multifunctional monolithic stretchable electronics.
Subscribe to Journal
Get full journal access for 1 year
only $17.42 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The main data supporting the findings of this study are available from the corresponding author upon request. Source data are provided with this paper.
Vatankhah-Varnosfaderani, M. et al. Mimicking biological stress–strain behaviour with synthetic elastomers. Nature 549, 497–501 (2017).
Rogers, J. A., Someya, T. & Huang, Y. G. Materials and mechanics for stretchable electronics. Science 327, 1603–1607 (2010).
Kaltenbrunner, M. et al. An ultra-lightweight design for imperceptible plastic electronics. Nature 499, 458–463 (2013).
Xu, S. et al. Stretchable batteries with self-similar serpentine interconnects and integrated wireless recharging systems. Nat. Commun. 4, 1543 (2013).
Lipomi, D. J., Tee, B. C. K., Vosgueritchian, M. & Bao, Z. N. Stretchable organic solar cells. Adv. Mater. 23, 1771–1775 (2011).
Oh, J. Y. et al. Intrinsically stretchable and healable semiconducting polymer for organic transistors. Nature 539, 411–415 (2016).
Cheng, S. & Wu, Z. G. A microfluidic, reversibly stretchable, large-area wireless strain sensor. Adv. Funct. Mater. 21, 2282–2290 (2011).
Agarwal, G., Besuchet, N., Audergon, B. & Paik, J. Stretchable materials for robust soft actuators towards assistive wearable devices. Sci. Rep. 6, 34224 (2016).
Sekitani, T. et al. Stretchable active-matrix organic light-emitting diode display using printable elastic conductors. Nat. Mater. 8, 494–499 (2009).
Guo, L. A. & DeWeerth, S. P. High-density stretchable electronics: toward an integrated multilayer composite. Adv. Mater. 22, 4030–4033 (2010).
Jiang, J. K. et al. Fabrication of transparent multilayer circuits by inkjet printing. Adv. Mater. 28, 1420–1426 (2016).
Tybrandt, K., Stauffer, F. & Voros, J. Multilayer patterning of high resolution intrinsically stretchable electronics. Sci. Rep. 6, 25641 (2016).
Tybrandt, K. & Voros, J. Fast and efficient fabrication of intrinsically stretchable multilayer circuit boards by wax pattern assisted filtration. Small 12, 180–184 (2016).
Byun, J. et al. A single droplet-printed double-side universal soft electronic platform for highly integrated stretchable hybrid electronics. Adv. Funct. Mater. 27, 1701912 (2017).
Huang, G. W. et al. Rapid laser printing of paper-based multilayer circuits. ACS Nano 10, 8895–8903 (2016).
Miyamoto, A. et al. Inflammation-free, gas-permeable, lightweight, stretchable on-skin electronics with nanomeshes. Nat. Nanotechnol. 12, 907–913 (2017).
Yang, W. et al. A breathable and screen-printed pressure sensor based on nanofiber membranes for electronic skins. Adv. Mater. Technol. 3, 1700241 (2018).
Park, S. J. & Tamura, T. Distribution of evaporation rate on human body surface. J. Physiol. Anthropol. 11, 593–609 (1992).
Fan, J. & Hunter, L. Engineering Apparel Fabrics and Garments (Woodhead Publishing, 2009).
Bucks, D., Guy, R. & Maibach, H. I. in In Vitro Percutaneous Absorption: Principles, Fundamentals, and Applications (eds Bronaugh, R. L. & H. Maibach, I.) Ch. 8 (CRC Press, 1991).
Van der Valk, P. G. & Maibach, H. I. Post-application occlusion substantially increases the irritant response of the skin to repeated short-term sodium lauryl sulfate (SLS) exposure. Contact Dermat. 21, 335–338 (1989).
Bucks, D. & Maibach, H. I. in Percutaneous Absorption: Drugs—Cosmetics—Mechanisms—Methodology 3rd edn (eds Bronaugh, R. L. & Maibach, H. I.) Ch. 4 (Marcel Dekker, 1999).
Kligman, A. M. in The Irritant Contact Dermatitis Syndrome (eds van der Valk, P. G. M. & Maibach, H. I.) Ch. 16 (CRC Press, 1996).
Zhai, H. & Maibach, H. I. Skin occlusion and irritant and allergic contact dermatitis: an overview. Contact Dermat. 44, 201–206 (2001).
Wei, S. Y. et al. Gas-permeable, irritation-free, transparent hydrogel contact lens devices with metal-coated nanofiber mesh for eye interfacing. ACS Nano 13, 7920–7929 (2019).
Du, W. Q. et al. Inflammation-free and gas-permeable on-skin triboelectric nanogenerator using soluble nanofibers. Nano Energy 51, 260–269 (2018).
Zhu, S. et al. Ultrastretchable fibers with metallic conductivity using a liquid metal alloy core. Adv. Funct. Mater. 23, 2308–2314 (2013).
Gozen, B. A., Tabatabai, A., Ozdoganlar, O. B. & Majidi, C. High-density soft-matter electronics with micron-scale line width. Adv. Mater. 26, 5211–5216 (2014).
Fassler, A. & Majidi, C. Liquid-phase metal inclusions for a conductive polymer composite. Adv. Mater. 27, 1928–1932 (2015).
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).
Parida, K. et al. Extremely stretchable and self-healing conductor based on thermoplastic elastomer for all-three-dimensional printed triboelectric nanogenerator. Nat. Commun. 10, 2158 (2019).
Thrasher, C. J. et al. Mechanoresponsive polymerized liquid metal networks. Adv. Mater. 31, 1903864 (2019).
Liang, S. et al. Liquid metal sponges for mechanically durable, all-soft, electrical conductors. J. Mater. Chem. C 5, 1586–1590 (2017).
Varga, M. et al. Adsorbed eutectic gain structures on a neoprene foam for stretchable MRI coils. Adv. Mater. 29, 1703744 (2017).
Dickey, M. D. Stretchable and soft electronics using liquid metals. Adv. Mater. 29, 1606425 (2017).
Matsuhisa, N., Chen, X. D., Bao, Z. A. & Someya, T. Materials and structural designs of stretchable conductors. Chem. Soc. Rev. 48, 2946–2966 (2019).
Diridollou, S. et al. In vivo model of the mechanical properties of the human skin under suction. Skin Res. Technol. 6, 214–221 (2000).
Hendriks, F. M. et al. A numerical-experimental method to characterize the non-linear mechanical behaviour of human skin. Skin Res. Technol. 9, 274–283 (2003).
Liu, Z. F. et al. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles. Science 349, 400–404 (2015).
Son, W. et al. Highly twisted supercoils for superelastic multi-functional fibres. Nat. Commun. 10, 426 (2019).
Regan, M. J. et al. X-ray study of the oxidation of liquid-gallium surfaces. Phys. Rev. B 55, 10786–10790 (1997).
Khan, M. R. et al. Influence of water on the interfacial behavior of gallium liquid metal alloys. ACS Appl. Mater. Interfaces 6, 22467–22473 (2014).
Yunusa, M., Amador, G. J., Drotlef, D. M. & Sitti, M. Wrinkling instability and adhesion of a highly bendable gallium oxide nanofilm encapsulating a liquid-gallium droplet. Nano Lett. 18, 2498–2504 (2018).
Guo, C. F. et al. Highly stretchable and transparent nanomesh electrodes made by grain boundary lithography. Nat. Commun. 5, 3121 (2014).
Lacour, S. P. et al. Stretchable interconnects for elastic electronic surfaces. Proc. IEEE 93, 1459–1467 (2005).
Yamada, T. et al. A stretchable carbon nanotube strain sensor for human-motion detection. Nat. Nanotechnol. 6, 296–301 (2011).
Tamayol, A. & Bahrami, M. Transverse permeability of fibrous porous media. Phys. Rev. E 83, 046314 (2011).
Draize, J. H. Methods for the study of irritation and toxicity of substances applied topically to the skin and mucous membranes. J. Pharmacol. Exp. Ther. 82, 377–390 (1944).
We acknowledge financial support from the Hong Kong Scholars (no. XJ2016051), Research Grants Council of Hong Kong (PolyU 153032/18P), National Natural Science Foundation of China (grant no. 51872095) and Key R&D Program of Guangzhou (no. 202007020003). We also appreciate the valuable discussion on thermal comfort with J. Fan from The Hong Kong Polytechnic University.
The authors declare no competing interests.
Peer review information Nature Materials thanks Jaehong Lee, Tsuyoshi Sekitani and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Figs. 1–17 and Tables 1 and 2.
This video shows the washing ability of the EGaIn-SBS mat. During the washing, no leakage of liquid metal was observed, and there was no obvious change in the performance of the LED array.
This video shows the air permeability of the electrospun SBS mat, EGaIn-SBS mat, multilayer EGaIn-SBS mat, PDMS film and Ecoflex film. The samples were wrapped onto a glass tube, through which air was blown into water.
Statistical source data for Fig. 1e, Fig. 1f and Fig. 1h.
Statistical source data for Fig. 3a, Fig. 3b and Fig. 3d.
Statistical source data for Fig. 4b and Fig. 4c.
Statistical source data for Fig. 5e.
Statistical source data for Fig. 6d, Fig. 6e, Fig. 6f and Fig. 6h.
About this article
Cite this article
Ma, Z., Huang, Q., Xu, Q. et al. Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics. Nat. Mater. (2021). https://doi.org/10.1038/s41563-020-00902-3