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Structured nanoscale metallic glass fibres with extreme aspect ratios


Micro- and nanoscale metallic glasses offer exciting opportunities for both fundamental research and applications in healthcare, micro-engineering, optics and electronics. The scientific and technological challenges associated with the fabrication and utilization of nanoscale metallic glasses, however, remain unresolved. Here, we present a simple and scalable approach for the fabrication of metallic glass fibres with nanoscale architectures based on their thermal co-drawing within a polymer matrix with matched rheological properties. Our method yields well-ordered and uniform metallic glasses with controllable feature sizes down to a few tens of nanometres, and aspect ratios greater than 1010. We combine fluid dynamics and advanced in situ transmission electron microscopy analysis to elucidate the interplay between fluid instability and crystallization kinetics that determines the achievable feature sizes. Our approach yields complex fibre architectures that, combined with other functional materials, enable new advanced all-in-fibre devices. We demonstrate in particular an implantable metallic glass-based fibre probe tested in vivo for a stable brain–machine interface that paves the way towards innovative high-performance and multifunctional neuro-probes.

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Fig. 1: Production of long, uniform, well-ordered micro- and nanoscale MGs via thermal drawing.
Fig. 2: Break-up of in-fibre MGs and their electron microscopy characterization.
Fig. 3: Size-dependent crystallization kinetics investigated via in situ TEM during heating.
Fig. 4: Composite and structured MGs in fibres.
Fig. 5: High-performance optoelectronic fibres using MG ribbons as electrodes.
Fig. 6: Neural stimulation and recording using MG-based fibre probes.

Data availability

Data that support the findings of this study are available from the corresponding author upon reasonable request. Source data are provided with this paper.

Code availability

All the scripts are available from the corresponding author upon request.


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F.S. thanks the Swiss CCMX Materials Challenge funding scheme, the Swiss National Science Foundation (grant no. 200021_146871) and the European Research Council (ERC Starting Grant 679211 ‘FLOWTONICS’) for their financial support. J.F.L. acknowledges financial support by the PREcision Additive Manufacturing of Precious metals Alloys (PREAMPA) project of the ETH domain and by an ETH research grant (ETH-47 17-1). G.C. acknowledges the European Research Council (ERC-2015-CoG HOW2WALKAGAIN 682999); G.S. acknowledges the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 665667; and S.P.L. thanks the Bertarelli Foundation for support.

Author information




W.Y., F.S. and J.F.L. conceived and designed the study. F.S. supervised the project. W.Y. and I.R. fabricated and characterized the fibres. G.K. and J.D.C. prepared the MG samples. I.R. and G.K. performed the differential scanning calorimetry measurements. W.Y. fabricated and characterized the optoelectronic fibres. I.R., W.Y. and T.N. performed the fluid instability modelling. W.Y. prepared the in situ TEM samples, V.T. performed the in situ TEM analysis and W.Y., R.I. and I.R. processed the in situ TEM data. W.Y. prepared the neural fibre probes with input from I.R.; G.S., I.R. and W.Y. characterized the neural probes, and N.J. performed the neural stimulation and recording. W.Y., I.R. and F.S. interpreted the outcome of the experiments, and all authors reviewed and extensively discussed the results. W.Y., I.R. and F.S. wrote the manuscript with input from all authors.

Corresponding author

Correspondence to Fabien Sorin.

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Competing interests

G.C. and S.P.L. are founders and shareholders of GTXmedical, a company developing neuroprothetic systems, not in direct relation with this work. The authors declare no competing interests.

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Extended data

Extended Data Fig. 1 Comparison of the figure of merit \(F = \frac{\sigma }{t}\) for in-fibre electrodes.

Average conductivity (σ), achievable feature size (t) and deduced figure of merit for structured MGs, and typical in-fibre crystalline metallic and conductive polymeric nanocomposite electrodes. Crystalline metals include liquid metals (for example gallium or galinstan)29, metals with “high” melting points (for example, Sn)28, eutectic alloys with intermediate melting points (for example, SnPb)51, and eutectic alloys with low melting points (for example, BiSn)52. Polymeric composites include carbon-loaded polycarbonate and carbon-loaded polyethylene29,36.

Extended Data Fig. 2 Electrochemical properties of in-fiber MGs.

The cyclic voltammetry (CV) (a) and voltage transient (VT) (b) in vitro characterization of in-fiber MGs for thousands of cycles. The CV measurements (a) illustrate that the stability of the CV curve is orders of magnitude greater than that of crystalline metallic electrodes, and is even on par with that of state-of-the-art carbon nanotubes and graphene fibers44,45 after 2,000 CV cycles. The electrodes were subject to 12k cycles at a scan rate of 100 mV/s between -0.6 and 0.8 V. VT measurements (b) for 100k cycles further demonstrate the long-term electrochemical stability of the MG electrodes. The electrodes were subject to 100k pulse cycles with a current amplitude of 50 µA at 40 Hz. Both measurements were repeated on three electrodes with similar results.

Source data

Extended Data Fig. 3 Localized neural inactivation using MG-based fibre probes.

a, Schematic representation of the experimental setup showing the locations of fibre implantations and the cross-section of the fibre probe that incorporates a chemotrode (3–4 mm length and 300 µm diameter). b, Representative traces of evoked EMG responses recorded from the biceps brachii (forelimb motor cortex stimulation) and the tibialis anterior (hindlimb motor cortex stimulation) before, during, and after injection of muscimol via the chemotrode on the fibre implanted in the hindlimb motor cortex. Similar observations were made in all animals implanted in this manner (n=2). c, Quantification of mean (±SEM) peak to peak amplitudes of EMG responses evoked during each condition (n=2, amplitude averaged from 20 responses in each animal during each condition).

Supplementary information

Supplementary Information

Supplementary Notes 1–12, Figs. 1–16, Tables 1 and 2 and refs. 1–24.

Reporting Summary

Supplementary Video 1

Video recording of the same rat responding to gradually increasing stimulus intensities delivered to the PPn depicting the increased locomotor speed at increased stimulation intensities. This effect was observed in all implanted animals (n = 6).

Source data

Source Data Fig. 3

Numerical data.

Source Data Fig. 5

Numerical data.

Source Data Extended Data Fig. 2

Numerical data.

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Yan, W., Richard, I., Kurtuldu, G. et al. Structured nanoscale metallic glass fibres with extreme aspect ratios. Nat. Nanotechnol. 15, 875–882 (2020).

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