Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

From metamaterials to metadevices

Metamaterials are man-made structures that allow optical properties to be shaped on length scales far smaller than the wavelength of light. Although metamaterials were initially considered mainly for static applications, this Review summarizes efforts towards an active functionality that enables a much broader range of photonic device applications.

Abstract

Metamaterials, artificial electromagnetic media that are structured on the subwavelength scale, were initially suggested for the negative-index 'superlens'. Later metamaterials became a paradigm for engineering electromagnetic space and controlling propagation of waves: the field of transformation optics was born. The research agenda is now shifting towards achieving tunable, switchable, nonlinear and sensing functionalities. It is therefore timely to discuss the emerging field of metadevices where we define the devices as having unique and useful functionalities that are realized by structuring of functional matter on the subwavelength scale. In this Review we summarize research on photonic, terahertz and microwave electromagnetic metamaterials and metadevices with functionalities attained through the exploitation of phase-change media, semiconductors, graphene, carbon nanotubes and liquid crystals. The Review also encompasses microelectromechanical metadevices, metadevices engaging the nonlinear and quantum response of superconductors, electrostatic and optomechanical forces and nonlinear metadevices incorporating lumped nonlinear components.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Reconfigurable metamaterials.
Figure 2: Electro-optical and liquid-crystal metadevices.
Figure 3: Phase-change and superconducting metadevices.
Figure 4: Ultrafast metadevices, varactor metamaterials and electromagnetic forces.

Similar content being viewed by others

References

  1. Ou, J. Y., Plum, E., Jiang, L. & Zheludev, N. I. Reconfigurable photonic metamaterials. Nano Lett. 11, 2142–2144 (2011).

    Article  CAS  Google Scholar 

  2. Lapine, M. et al. Structural tunability in metamaterials. Appl. Phys. Lett. 95, 084105 (2009).

    Article  CAS  Google Scholar 

  3. Karim, M. F., Liu, A. Q., Alphones, A. & Yu, A. B. A tunable bandstop filter via the capacitance change of micromachined switches. J. Micromech. Microeng. 16, 851–861 (2006).

    Article  CAS  Google Scholar 

  4. Gil, I., Martin, F., Rottenberg, X. & De Raedt, W. Tunable stop-band filter at Q-band based on RF-MEMS metamaterials. Electron. Lett. 43, 1153–1154 (2007).

    Article  Google Scholar 

  5. Hand, T. & Cummer, S. Characterization of tunable metamaterial elements using MEMS switches. IEEE Antennas Wireless Propag. Lett. 6, 401–404 (2007).

    Article  Google Scholar 

  6. Tao, H. et al. Reconfigurable terahertz metamaterials. Phys. Rev. Lett. 103, 147401 (2009).

    Article  CAS  Google Scholar 

  7. He, X., Lv, Z., Liu, B. & Li, Z. Tunable magnetic metamaterial based multi-split-ring resonator (MSRR) using MEMS switch components. Microsyst. Technol. Micro Nanosyst. Inform. Storage Process. Syst. 17, 1263–1269 (2011).

    Google Scholar 

  8. Zhu, W. M. et al. Switchable magnetic metamaterials using micromachining processes. Adv. Mater. 23, 1792–1796 (2011).

    Article  CAS  Google Scholar 

  9. Fu, Y. H. et al. A micromachined reconfigurable metamaterial via reconfiguration of asymmetric split-ring resonators. Adv. Funct. Mater. 21, 3589–3594 (2011).

    Article  CAS  Google Scholar 

  10. Ozbey, B. & Aktas, O. Continuously tunable terahertz metamaterial employing magnetically actuated cantilevers. Opt. Express 19, 5741–5752 (2011).

    Article  CAS  Google Scholar 

  11. Pryce, I. M., Aydin, K., Kelaita, Y. A., Briggs, R. M. & Atwater, H. A. Highly strained compliant optical metamaterials with large frequency tunability. Nano Lett. 10, 4222–4227 (2010).

    Article  CAS  Google Scholar 

  12. Tao, H. et al. Metamaterial silk composites at terahertz frequencies. Adv. Mater. 22, 3527–3531 (2010).

    Article  CAS  Google Scholar 

  13. Aksu, S. et al. Flexible plasmonics on unconventional and nonplanar substrates. Adv. Mater. 23, 4422–4430 (2011).

    Article  CAS  Google Scholar 

  14. Kasirga, T. S., Ertas, Y. N. & Bayindir, M. Microfluidics for reconfigurable electromagnetic metamaterials. Appl. Phys. Lett. 95, 214102 (2009).

    Article  CAS  Google Scholar 

  15. Ou, J. Y., Plum, E. & Zheludev, N. I. MHz bandwidth electro-optical modulator based on a reconfigurable photonic metamaterial. CLEO/QELS Conf. Poster JW4A.11 (2012).

  16. Chen, H-T. et al. Active terahertz metamaterial devices. Nature 444, 597–600 (2006).

    Article  CAS  Google Scholar 

  17. Shrekenhamer, D. et al. High speed terahertz modulation from metamaterials with embedded high electron mobility transistors. Opt. Express 19, 9968–9975 (2011).

    Article  CAS  Google Scholar 

  18. Chan, W. L. et al. A spatial light modulator for terahertz beams. Appl. Phys. Lett. 94, 213511 (2009).

    Article  CAS  Google Scholar 

  19. Zhang, S. et al. Photoinduced handedness switching in terahertz chiral metamolecules. Nature Commun. 3, 942 (2012).

    Article  CAS  Google Scholar 

  20. Feigenbaum, E., Diest, K. & Atwater, H. A. Unity-order index change in transparent conducting oxides at visible frequencies. Nano Lett. 10, 2111–2116 (2010).

    Article  CAS  Google Scholar 

  21. Gil, M. et al. Electrically tunable split-ring resonators at microwave frequencies based on barium-strontium-titanate thick films. Electron. Lett. 45, 417–418 (2009).

    Article  CAS  Google Scholar 

  22. Papasimakis, N. et al. Graphene in a photonic metamaterial. Opt. Express 18, 8353–8359 (2010).

    Article  CAS  Google Scholar 

  23. Yan, H. G. et al. Tunable infrared plasmonic devices using graphene/insulator stacks. Nature Nanotech. 7, 330–334 (2012).

    Article  CAS  Google Scholar 

  24. Ju, L. et al. Graphene plasmonics for tunable terahertz metamaterials. Nature Nanotech. 6, 630–634 (2011).

    Article  CAS  Google Scholar 

  25. Wang, X. et al. Tunable optical negative-index metamaterials employing anisotropic liquid crystals. Appl. Phys. Lett. 91, 143122 (2007).

    Article  CAS  Google Scholar 

  26. Zhao, Q. et al. Electrically tunable negative permeability metamaterials based on nematic liquid crystals. Appl. Phys. Lett. 90, 011112 (2007).

    Article  CAS  Google Scholar 

  27. Zhang, F. L. et al. Voltage tunable short wire-pair type of metamaterial infiltrated by nematic liquid crystal. Appl. Phys. Lett. 97, 134103 (2010).

    Article  CAS  Google Scholar 

  28. Zhang, F. L. et al. Electrically controllable fishnet metamaterial based on nematic liquid crystal. Opt. Express 19, 1563–1568 (2011).

    Article  CAS  Google Scholar 

  29. Zhang, F. et al. Magnetic control of negative permeability metamaterials based on liquid crystals. Appl. Phys. Lett. 92, 193104 (2008).

    Article  CAS  Google Scholar 

  30. Xiao, S. M. et al. Tunable magnetic response of metamaterials. Appl. Phys. Lett. 95, 033115 (2009).

    Article  CAS  Google Scholar 

  31. Kang, B. et al. Optical switching of near infrared light transmission in metamaterial-liquid crystal cell structure. Opt. Express 18, 16492–16498 (2010).

    Article  CAS  Google Scholar 

  32. Minovich, A. et al. Liquid crystal based nonlinear fishnet metamaterials. Appl. Phys. Lett. 100, 121113 (2012).

    Article  CAS  Google Scholar 

  33. Zheludev, N. All change, please. Nature Photon. 1, 551–553 (2007).

    Article  CAS  Google Scholar 

  34. Krasavin, A. V., MacDonald, K. F., Schwanecke, A. S. & Zheludev, N. I. Gallium/aluminum nanocomposite material for nonlinear optics and nonlinear plasmonics. Appl. Phys. Lett. 89, 031118 (2006).

    Article  CAS  Google Scholar 

  35. Bennett, P. J. et al. A photonic switch based on a gigantic, reversible optical nonlinearity of liquefying gallium. Appl. Phys. Lett. 73, 1787–1789 (1998).

    Article  CAS  Google Scholar 

  36. Driscoll, T. et al. Dynamic tuning of an infrared hybrid-metamaterial resonance using vanadium dioxide. Appl. Phys. Lett. 93, 024101 (2008).

    Article  CAS  Google Scholar 

  37. Seo, M. et al. Active terahertz nanoantennas based on VO2 phase transition. Nano Lett. 10, 2064–2068 (2010).

    Article  CAS  Google Scholar 

  38. Huang, W-x. et al. Optical switching of a metamaterial by temperature controlling. Appl. Phys. Lett. 96, 261908 (2010).

    Article  CAS  Google Scholar 

  39. Appavoo, K. & Haglund, R. F. Jr Detecting nanoscale size dependence in VO2 phase transition using a split-ring resonator metamaterial. Nano Lett. 11, 1025–1031 (2011).

    Article  CAS  Google Scholar 

  40. Driscoll, T. et al. Memory metamaterials. Science 325, 1518–1521 (2009).

    Article  CAS  Google Scholar 

  41. Samson, Z. L. et al. Metamaterial electro-optic switch of nanoscale thickness. Appl. Phys. Lett. 96, 143105 (2010).

    Article  CAS  Google Scholar 

  42. Gholipour, B. et al. Chalcogenide glass photonics: non-volatile, bi-directional, all-optical switching in phase-change metamaterials. CLEO/QELS Conf. Paper CF2A.3 (2012).

  43. Simpson, R. E. et al. Interfacial phase-change memory. Nature Nanotech. 6, 501–505 (2011).

    Article  CAS  Google Scholar 

  44. Tsiatmas, A., Fedotov, A. V. & Zheludev, N. I. Plasmonics without losses? (The case for terahertz superconducting plasmonics). New J. Phys. (in the press). Preprint at http://arxiv.org/abs/1105.3045 (2011).

  45. Ricci, M., Orloff, N. & Anlage, S. M. Superconducting metamaterials. Appl. Phys. Lett. 87, 034102 (2005).

    Article  CAS  Google Scholar 

  46. Fedotov, V. A. et al. Temperature control of Fano resonances and transmission in superconducting metamaterials. Opt. Express 18, 9015–9019 (2010).

    Article  CAS  Google Scholar 

  47. Chen, H-T. et al. Tuning the resonance in high-temperature superconducting terahertz metamaterials. Phys. Rev. Lett. 105, 247402 (2010).

    Article  CAS  Google Scholar 

  48. Gu, J. Q. et al. Terahertz superconductor metamaterial. Appl. Phys. Lett. 97, 071102 (2010).

    Article  CAS  Google Scholar 

  49. Jin, B. B. et al. Low loss and magnetic field-tunable superconducting terahertz metamaterial. Opt. Express 18, 17504–17509 (2010).

    Article  CAS  Google Scholar 

  50. Tsiatmas, A. et al. Superconducting plasmonics and extraordinary transmission. Appl. Phys. Lett. 97, 111106 (2010).

    Article  CAS  Google Scholar 

  51. Wu, J. B. et al. Tuning of superconducting niobium nitride terahertz metamaterials. Opt. Express 19, 12021–12026 (2011).

    Article  CAS  Google Scholar 

  52. Pimenov, A., Loidl, A., Przyslupski, P. & Dabrowski, B. Negative refraction in ferromagnet-superconductor superlattices. Phys. Rev. Lett. 95, 247009 (2005).

    Article  CAS  Google Scholar 

  53. Kurter, C. et al. Superconducting RF metamaterials made with magnetically active planar spirals. IEEE Trans. Appl. Supercond. 21, 709–712 (2011).

    Article  CAS  Google Scholar 

  54. Ricci, M. C. et al. Tunability of superconducting metamaterials. IEEE Trans. Appl. Supercond. 17, 918–921 (2007).

    Article  CAS  Google Scholar 

  55. Savinov, V., Fedotov, V. A., de Groot, P. A. & Zheludev, N. I. Electro-optical modulation of sub-terahertz radiation with superconducting metamaterial. CLEO/QELS Conf. Paper CTh1D.1 (2012).

  56. Kurter, C. et al. Classical analogue of electromagnetically induced transparency with a metal–superconductor hybrid metamaterial. Phys. Rev. Lett. 107, 043901 (2011).

    Article  CAS  Google Scholar 

  57. Kurter, C. et al. Switching nonlinearity in a superconductor-enhanced metamaterial. Appl. Phys. Lett. 100, 121906 (2012).

    Article  CAS  Google Scholar 

  58. Du, C. G., Chen, H. Y. & Li, S. Q. Quantum left-handed metamaterial from superconducting quantum-interference devices. Phys. Rev. B 74, 113105 (2006).

    Article  CAS  Google Scholar 

  59. Lazarides, N. & Tsironis, G. P. RF superconducting quantum interference device metamaterials. Appl. Phys. Lett. 90, 163501 (2007).

    Article  CAS  Google Scholar 

  60. Rakhmanov, A. L., Zagoskin, A. M., Savel'ev, S. & Nori, F. Quantum metamaterials: electromagnetic waves in a Josephson qubit line. Phys. Rev. B 77, 144507 (2008).

    Article  CAS  Google Scholar 

  61. Savinov, V. et al. Flux exclusion quantum superconducting metamaterial: towards quantum-level switching. Sci. Rep. 2, 450 (2012).

    Article  CAS  Google Scholar 

  62. Wood, B. et al. A d.c. magnetic metamaterial. Nature Mater. 7, 295–297 (2008).

    Article  CAS  Google Scholar 

  63. Navau, C., Chen, D. X., Sanchez, A. & Del-Valle, N. Magnetic properties of a dc metamaterial consisting of parallel square superconducting thin plates. Appl. Phys. Lett. 94, 242501 (2009).

    Article  CAS  Google Scholar 

  64. Sanchez, A., Navau, C., Prat-Camps, J. & Chen, D. X. Antimagnets: controlling magnetic fields with superconductor-metamaterial hybrids. New J. Phys. 13, 093034 (2011).

    Article  CAS  Google Scholar 

  65. Gomory, F. et al. Experimental realization of a magnetic cloak. Science 335, 1466–1468 (2012).

    Article  CAS  Google Scholar 

  66. Padilla, W. J., Taylor, A. J., Highstrete, C., Lee, M. & Averitt, R. D. Dynamical electric and magnetic metamaterial response at terahertz frequencies. Phys. Rev. Lett. 96, 107401 (2006).

    Article  CAS  Google Scholar 

  67. Chen, H-T. et al. Ultrafast optical switching of terahertz metamaterials fabricated on ErAs/GaAs nanoisland superlattices. Opt. Lett. 32, 1620–1622 (2007).

    Article  CAS  Google Scholar 

  68. Cho, D. J. et al. Ultrafast modulation of optical metamaterials. Opt. Express 17, 17652–17657 (2009).

    Article  CAS  Google Scholar 

  69. Dani, K. M. et al. Subpicosecond optical switching with a negative index metamaterial. Nano Lett. 9, 3565–3569 (2009).

    Article  CAS  Google Scholar 

  70. Nikolaenko, A. E. et al. Carbon nanotubes in a photonic metamaterial. Phys. Rev. Lett. 104, 153902 (2010).

    Article  CAS  Google Scholar 

  71. Nikolaenko, A. E. et al. Nonlinear graphene metamaterial. Appl. Phys. Lett. 100, 181109 (2012).

    Article  CAS  Google Scholar 

  72. Ren, M. X. et al. Nanostructured plasmonic medium for terahertz bandwidth all-optical switching. Adv. Mater. 23, 5540–5544 (2011).

    Article  CAS  Google Scholar 

  73. Ren, M., Plum, E., Xu, J. & Zheludev, N. I. Giant nonlinear optical activity in a plasmonic metamaterial. Nature Commun. 3, 833 (2012).

    Article  CAS  Google Scholar 

  74. Wurtz, G. A. et al. Designed ultrafast optical nonlinearity in a plasmonic nanorod metamaterial enhanced by nonlocality. Nature Nanotech. 6, 106–110 (2011).

    Article  CAS  Google Scholar 

  75. Zhang, J., MacDonald, K. F. & Zheludev, N. I. Controlling light-with-light without nonlinearity. Light 1, e18 (2012).

    Article  CAS  Google Scholar 

  76. Zharov, A. A., Shadrivov, I. V. & Kivshar, Y. S. Nonlinear properties of left-handed metamaterials. Phys. Rev. Lett. 91, 037401 (2003).

    Article  CAS  Google Scholar 

  77. Lapine, M., Gorkunov, M. & Ringhofer, K. H. Nonlinearity of a metamaterial arising from diode insertions into resonant conductive elements. Phys. Rev. E 67, 065601 (2003).

    Article  CAS  Google Scholar 

  78. Shadrivov, I. V., Kozyrev, A. B., van der Weide, D. & Kivshar, Y. S. Nonlinear magnetic metamaterials. Opt. Express 16, 20266–20271 (2008).

    Article  CAS  Google Scholar 

  79. Shadrivov, I. V., Kozyrev, A. B., van der Weide, D. W. & Kivshar, Y. S. Tunable transmission and harmonic generation in nonlinear metamaterials. Appl. Phys. Lett. 93, 161903 (2008).

    Article  CAS  Google Scholar 

  80. Powell, D. A., Shadrivov, I. V. & Kivshar, Y. S. Nonlinear electric metamaterials. Appl. Phys. Lett. 95, 084102 (2009).

    Article  CAS  Google Scholar 

  81. Carbonell, J., Boria, V. E. & Lippens, D. Nonlinear effects in split ring resonators loaded with heterostructure barrier varactors. Microwave Opt. Technol. Lett. 50, 474–479 (2008).

    Article  Google Scholar 

  82. Wiltshire, M. C. K. Tuning Swiss roll metamaterials. J. Phys. D Appl. Phys. 42, 205001 (2009).

    Article  CAS  Google Scholar 

  83. Shadrivov, I. V., Morrison, S. K. & Kivshar, Y. S. Tunable split-ring resonators for nonlinear negative-index metamaterials. Opt. Express 14, 9344–9349 (2006).

    Article  Google Scholar 

  84. Wang, B. N., Zhou, J. F., Koschny, T. & Soukoulis, C. M. Nonlinear properties of split-ring resonators. Opt. Express 16, 16058–16063 (2008).

    Article  Google Scholar 

  85. Huang, D., Poutrina, E. & Smith, D. R. Analysis of the power dependent tuning of a varactor-loaded metamaterial at microwave frequencies. Appl. Phys. Lett. 96, 104104 (2010).

    Article  CAS  Google Scholar 

  86. Poutrina, E., Huang, D. & Smith, D. R. Analysis of nonlinear electromagnetic metamaterials. New J. Phys. 12, 093010 (2010).

    Article  CAS  Google Scholar 

  87. Powell, D. A., Shadrivov, I. V., Kivshar, Y. S. & Gorkunov, M. V. Self-tuning mechanisms of nonlinear split-ring resonators. Appl. Phys. Lett. 91, 144107 (2007).

    Article  CAS  Google Scholar 

  88. Shadrivov, I. V., Fedotov, V. A., Powell, D. A., Kivshar, Y. S. & Zheludev, N. I. Electromagnetic wave analogue of an electronic diode. New J. Phys. 13, 033025 (2011).

    Article  CAS  Google Scholar 

  89. Larouche, S., Rose, A., Poutrina, E., Huang, D. & Smith, D. R. Experimental determination of the quadratic nonlinear magnetic susceptibility of a varactor-loaded split ring resonator metamaterial. Appl. Phys. Lett. 97, 011109 (2010).

    Article  CAS  Google Scholar 

  90. Katko, A. R. et al. Phase conjugation and negative refraction using nonlinear active metamaterials. Phys. Rev. Lett. 105, 123905 (2010).

    Article  CAS  Google Scholar 

  91. Huang, D., Rose, A., Poutrina, E., Larouche, S. & Smith, D. R. Wave mixing in nonlinear magnetic metacrystal. Appl. Phys. Lett. 98, 204102 (2011).

    Article  CAS  Google Scholar 

  92. Rose, A., Huang, D. & Smith, D. R. Controlling the second harmonic in a phase-matched negative-index metamaterial. Phys. Rev. Lett. 107, 063902 (2011).

    Article  CAS  Google Scholar 

  93. Kanazawa, T., Tamayama, Y., Nakanishi, T. & Kitano, M. Enhancement of second harmonic generation in a doubly resonant metamaterial. Appl. Phys. Lett. 99, 024101 (2011).

    Article  CAS  Google Scholar 

  94. Agranovich, V. M., Shen, Y. R., Baughman, R. H. & Zakhidov, A. A. Linear and nonlinear wave propagation in negative refraction metamaterials. Phys. Rev. B 69, 165112 (2004).

    Article  CAS  Google Scholar 

  95. Shadrivov, I. V., Zharov, A. A. & Kivshar, Y. S. Second-harmonic generation in nonlinear left-handed metamaterials. J. Opt. Soc. Am. B 23, 529–534 (2006).

    Article  CAS  Google Scholar 

  96. Gil, I., Bonache, J., Garcia-Garcia, J. & Martin, F. Tunable metamaterial transmission lines based on varactor-loaded split-ring resonators. IEEE Trans. Microwave Theory Techniques 54, 2665–2674 (2006).

    Article  Google Scholar 

  97. Velez, A., Bonache, J. & Martin, F. Doubly tuned metamaterial transmission lines based on complementary split-ring resonators. Electromagnetics 28, 523–530 (2008).

    Article  Google Scholar 

  98. Wang, Y. F., Yin, J. C., Yuan, G. S., Dong, X. C. & Du, C. L. Tunable I-shaped metamaterial by loading varactor diode for reconfigurable antenna. Appl. Phys. A 104, 1243–1247 (2011).

    Article  CAS  Google Scholar 

  99. Lapine, M., Shadrivov, I. V., Powell, D. A. & Kivshar, Y. S. Magnetoelastic metamaterials. Nature Mater. 11, 30–33 (2012).

    Article  CAS  Google Scholar 

  100. Lapine, M., Shadrivov, I. V., Powell, D. A. & Kivshar, Y. S. Metamaterials with conformational nonlinearity. Sci. Rep. 1, 138 (2011).

    Article  CAS  Google Scholar 

  101. Zhao, R. K., Tassin, P., Koschny, T. & Soukoulis, C. M. Optical forces in nanowire pairs and metamaterials. Opt. Express 18, 25665–25676 (2010).

    Article  CAS  Google Scholar 

  102. Zhang, J., MacDonald, F. M. & Zheludev, N. I. Optical gecko toe: optically controlled attractive near-field forces between plasmonic metamaterials and dielectric or metal surfaces. Phys. Rev. B 85, 205123 (2012).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank I. Yangs for discussions, and T. Roy and D. Powel for assistance with preparing the manuscript. We acknowledge the support of the Defence Science and Technology Laboratory (UK), Engineering and Physical Sciences Research Council (UK), Royal Society (London), Australian Research Council and collaboration support through the Centre for Ultrahigh-bandwidth Devices for Optical Systems (Australia), and Ministry of Education, Singapore, grant number MOE2011-T3-1-005.

Author information

Authors and Affiliations

Authors

Contributions

N.I.Z initiated the sections on reconfigurable, electro-optical, phase change, superconducting and ultrafast metadevices; Y.S.K initiated the sections on liquid crystal metadevices, nonlinear metadevices with varactors and metadevices driven by electromagnetic forces; both authors contributed equally to editing.

Corresponding author

Correspondence to Nikolay I. Zheludev.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Zheludev, N., Kivshar, Y. From metamaterials to metadevices. Nature Mater 11, 917–924 (2012). https://doi.org/10.1038/nmat3431

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat3431

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing