Tapered fibertrodes for optoelectrical neural interfacing in small brain volumes with reduced artefacts

• Published in: Nature materials Vol. 21; no. 7; pp. 826 - 835
• Main Authors: Spagnolo, Barbara, Balena, Antonio, Peixoto, Rui T., Pisanello, Marco, Sileo, Leonardo, Bianco, Marco, Rizzo, Alessandro, Pisano, Filippo, Qualtieri, Antonio, Lofrumento, Dario Domenico, De Nuccio, Francesco, Assad, John A., Sabatini, Bernardo L., De Vittorio, Massimo, Pisanello, Ferruccio
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2022; Nature Publishing Group
• Subjects: 142/126; 631/1647/2253; 639/166/987; 639/766/1130; Biomaterials; Brain; Chemistry and Materials Science; Condensed Matter Physics; Electrodes; Fabrication; Light emission; Materials Science; Microelectrodes; Nanotechnology; Neural prostheses; Neurons; Optical and Electronic Materials; Optical fibers; Optoelectronic devices; Photoelectricity; Recording; Temporal resolution; Transplants & implants
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-022-01272-8

Deciphering the neural patterns underlying brain functions is essential to understanding how neurons are organized into networks. This deciphering has been greatly facilitated by optogenetics and its combination with optoelectronic devices to control neural activity with millisecond temporal resolution and cell type specificity. However, targeting small brain volumes causes photoelectric artefacts, in particular when light emission and recording sites are close to each other. We take advantage of the photonic properties of tapered fibres to develop integrated ‘fibertrodes’ able to optically activate small brain volumes with abated photoelectric noise. Electrodes are positioned very close to light emitting points by non-planar microfabrication, with angled light emission allowing the simultaneous optogenetic manipulation and electrical read-out of one to three neurons, with no photoelectric artefacts, in vivo. The unconventional implementation of two-photon polymerization on the curved taper edge enables the fabrication of recoding sites all around the implant, making fibertrodes a promising complement to planar microimplants. Here the authors fabricate a fibre-coupled electrode ‘fibertrode’ that integrates light emission sites and platinum microelectrodes on tapered optical fibre neural implants, for combined stimulation and recording of neural activity over small brain volumes in vivo with reduced photoelectric artefacts.