CNT sheet-based fiber-type neural interfaces

Abstract

Neural interfaces have evolved to open new possibilities in research methodologies in neuroscience. Here specifically, the development of flexible and biocompatible neural interfaces has enabled long-term observation of neural circuits. In this thesis, the development and application of a novel fiber-type neural interface are proposed. The device was designed to accommodate multiple functionalities geared toward optogenetics such as optical stimulations and electrophysiological recording via the thermal drawing processing (TDP) and additional assembly of external components. In detail, the TDP was first used to fabricate polymer waveguide fibers that consist of PC and PMMA. And then, CNT sheets drawn from vertically oriented nanotube arrays (forests) were manually wrapped on the surface of the fiber to be utilized as an organic electrode. Due to the manufacturing scheme, all components of the device are aligned longitudinally and exhibit radial symmetry of functionality at the fiber tip. We demonstrate that CNT sheet-based neural fibers are capable of recording of multi-unit activity with simultaneous optical stimulation in the CA3 hippocampus of transgenic $\textit{Thy1-ChR2-eYFP}$ mice. We also confirm the behavioral response of locomotor activation and hindlimb movement through optical stimulation of the M2 cortex and spinal cord, respectively. Some further suggestions regarding the future potential of these fibers including applications in spinal cord optogenetic experiments, miniature bundle type fibers, and MRI compatible devices are given. Through these studies, it is shown that the proposal of this device as well as the novel scheme of the CNT-sheet electrodes and its integration present a versatile platform for next-generation integrated multifunctional device fabrication.