Available on-demand - F.FL02.06.02
Structured Metallic Glass-Based Multimaterial Fibers for Efficient Neural Stimulation and Recording
Wei Yan1,2,Nicholas D. James3,Inès Richard1,Güven Kurtuldu4,Giuseppe Schiavone5,Jordan Squair3,Reinis Ignatans6,Stephanie Lacour5,Vasiliki Tileli6,Grégoire Courtine3,Jörg Löffler4,Fabien Sorin1
École Polytechnique Fédérale de Lausanne1,Massachusetts Institute of Technology2,École Polytechnique Fédérale de Lausanne, University Hospital of Vaud, and University of Lausanne3,Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich4,Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Microengineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne5,Institute of Materials, École Polytechnique Fédérale de Lausanne6
Recent advances in techniques and methodologies for dissecting complex neural circuits are poised to unravel the function of neural networks and the underlying causes of neurological diseases1. Electrical stimulation of neural tissue and recording of neural activity play critical roles for our understanding of information transfer and processing within the nervous system. The traditional strategy for this purpose mainly exploits metal-based microwires that are mechanically and biologically incompatible with tissue. Recently, thermally-drawn multimaterial fibers that integrate electrodes and other modalities have emerged as promising tools for deciphering the neural circuitry in a unique way2-4. The development of in-fiber electrodes with low impedances, small feature sizes, arbitrary geometries and excellent electrochemical properties that allow for efficient both electrical stimulation and recording, however, remains challenging. Here we, for the first time, achieve such capability via thermal drawing of a peculiar material system — metallic glasses (MGs) — that is metallic yet exhibits disordered atomic-scale structure within a polymer matrix5. Thanks to the control over the interplay between fluid instabilities and crystallization dynamics, we are able to fabricate ultra-long MG electrodes spanning a wide size range from a few micrometers to around 40 nm. Designing the structures in a macroscopic scaled-up preform enables the fabrication of structured MGs with arbitrary transverse geometries previously unachievable. The electrochemical characterization reveal that these novel MG electrodes surpass in all accounts typical in-fiber electrodes including metallic or polymeric electrodes found in state-of-the-art fiber probes. The charge storage capacity is superior compared to typical metallic electrodes such as commercialized Pt and PtIr. The electrochemical stability is demonstrated by the long-term cyclic voltammetry and voltage transient cycles, is even on par with that of the state-of-art carbon nanotube and graphene fibers5. These merits can be attributed to the intrinsic microstructural homogeneity and isotropy of structured MGs. We demonstrate the unique applications of these fiber probes integrating multiple MG conductors embedded in a biocompatible polymer, and microfluidic channels for electrical stimulation and recording plus localized pharmacological manipulation in the deep brain of animals. Specifically, chronic experiments in rats show the ability to elicit robust behavioral responses when delivering electrical neurostimulation in deep structures, to record neuronal activity during unconstrained locomotion, and to deliver pharmacological agents to manipulate local circuits. Our MG probes are implantable, miniaturized and fully functional to form stable brain-machine interfaces in freely moving animals paving the way towards innovative long-term, multi-functional neuro-probes.
W.Y, N.J contributed equally.
1. Wei Yan, et al. Advanced Multimaterial Electronic and Optoelectronic Fibers and Textiles. Advanced Materials 31 (2019) 1802348.
2. Canales, A. et al. Multifunctional fibers for simultaneous optical, electrical and chemical interrogation of neural circuits in vivo. Nat. Biotechnol. 33, 277–284 (2015).
3. Guo, Y. et al. Polymer Composite with Carbon Nanofibers Aligned during Thermal Drawing as a Microelectrode for Chronic Neural Interfaces. ACS Nano 11, 6574–6585 (2017).
4. Frank, J. et al. Next-generation interfaces for studying neural function. Nature Biotechnology 37, 1013-1023 (2019).
5. Wei Yan, Inès Richard, Güven Kurtuldu, Niclolas James, Giuseppe Schiavone, Tung Nguyen-Dang, Tapajyoti Das Gupta, Yunpeng Qu, Jake Cao, Reinis Ignatans, Stéphanie P. Lacour, Vasiliki Tileli, Grégoire Courtine, Jörg F. Löffler, Fabien Sorin*. Structured nanoscale metallic glasses fibers with extreme aspect ratios. Nature Nanotechnology. (In press, 2020).