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Res Sq
ResearchSquare
Research Square
2693-5015
American Journal Experts

39184098
10.21203/rs.3.rs-4693073/v1
10.21203/rs.3.rs-4693073
preprint
1
Article
Anisotropic Hydrogel Microelectrodes for Intraspinal Neural Recordings in vivo
Rao Siyuan https://orcid.org/0000-0002-1555-487X

Huang Sizhe
Xiao Ruobai
Lin Shaoting
Hong Eunji
Jang Geunho
Gupta Shovit
Lu Fake
Chen Bo
Liu Xinyue https://orcid.org/0000-0002-1187-493X

Sahasrabudhe Atharva
Zhang Zicong
He Zhigang https://orcid.org/0000-0001-6080-6880

Crosby Alfred
Sumaria Kaushal
Liu Tingyi
Wang Qianbin https://orcid.org/0000-0002-9840-6732

14 8 2024
rs.3.rs-4693073https://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License, which allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use.
https://www.researchsquare.com/article/rs-4693073/v1
nihpp-rs4693073v1.pdf
Abstract

Creating durable, motion-compliant neural interfaces is crucial for accessing dynamic tissues under in vivo conditions and linking neural activity with behaviors. Utilizing the self-alignment of nano-fillers in a polymeric matrix under repetitive tension, here, we introduce conductive carbon nanotubes with high aspect ratios into semi-crystalline polyvinyl alcohol hydrogels and create electrically anisotropic percolation pathways through cyclic stretching. The resulting anisotropic hydrogel fibers (diameter of 187 ± 13 µm) exhibit fatigue resistance (20,000 cycles at 20% strain) with a stretchability of 64.5 ± 7.9%, and low electrochemical impedance (900 ± 149 kΩ @ 1kHz). We observe the re-constructed nanofillers’ axial alignment and a corresponding anisotropic impedance decrease along the direction of cyclic stretching. We fabricate fiber-shaped hydrogels into bioelectronic devices and implant them into wild-type and transgenic Thy1-ChR2-EYFP mice to record electromyographic signals from muscles in anesthetized and freely moving conditions. These hydrogel fibers effectively enable the simultaneous recording of electrical signals from ventral spinal cord neurons and the tibialis anterior muscles during optogenetic stimulation. Importantly, the devices maintain functionality with repeatable recording results over eight months after implantation, demonstrating their durability and potential for long-term monitoring in neurophysiological studies.
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