Magnetic resonance identification tags for ultra-flexible electrodes

Eminhan Özil, Peter Gombkoto, Athina Apostolelli, Tansel Baran Yasar, Angeliki D. Vavladeli, Markus Marks, Manabu Rohr-Fukuma, Wolfger von der Behrens, Mehmet Fatih Yanik

Abstract: Ultra-flexible electrodes, due to their superior biocompatibility, are likely to lead the future of neuroprosthetics. However, identifying the precise positions of implanted high-density ultra-flexible electrodes in the brain for accurately assigning neural signals to specific structures remains a major challenge. To address this, we developed magnetic resonance identification (MRID)-tags. Each ultra-flexible electrode bundle carries an MRID-tag with unique barcode patterns visible in MRI (MRI-barcodes) for identification of the bundle. Individual bars in MRI-barcodes allow an accurate 3D reconstruction of the ultra-flexible electrode bundle’s trajectory in the brain and determine the anatomical positions of individual electrodes. We generate the MRI-barcodes by patterning superparamagnetic iron-oxide nanoparticles into electrode fibers (10 µm2) with dot-matrix nanoparticle coating technique. We chronically tested MRID-tagged ultra-flexible electrodes in vivo in the dorsal hippocampus of freely-moving rats, where distinct electrophysiological landmarks validated our electrode localization results. We were able to localize individual electrodes with a mean accuracy of 95 μm. MRID-tagged ultra-flexible electrodes demonstrated high long-term recording stability with mean single-unit signal-to-noise ratios as high as 20. Flexible electrodes offer higher biocompatibility but remain difficult to locate inside the brain, limiting data interpretation and targeting. Here, the authors demonstrate electrodes with magnetic tags for identification and localization.

External IDs:doi:10.1038/s41467-026-71887-x