Self-supporting carbon nanotube films as flexible neural interfaces

Abstract

Advances in neural interface technologies have sought to identify electroactive materials that are able to translate neural depolarisation events into digital signals or modulate neural firing through ionic or electrical stimulation with greater efficiency. An ideal material for neural recording and/or stimulation should possess low electrical impedance coupled with a high cathodic charge storage capacity (CSC C ), charge injection capacity (CIC) and electroactive surface area (ESA), as well as optimal mechanical biomimicry. In this study, we present the robustness of self-supporting CNT films as neural interfaces, combining advantageous electrical and mechanical properties with high cytocompatibility. Films were observed to possess a high CSC C (29.95 ± 0.91 mC cm -2 ), CIC (352 ± 5 µC V -1 cm -2 ) and ESA (0.908 ± 0.053 cm 2 ), low impedance (110 Ω at 1 kHz), low resistance (75 ± 13 Ω) and high capacitance (378 ± 9 µF cm -2 ), and outperformed Pt control electrodes. Self-supporting CNT films were also found to facilitate neuron growth and decrease the presence of reactive astrocytes in a mixed neural cell population. Self-standing CNT films were shown to be promising materials for the design of flexible and cytocompatible neural interfaces.

Platinum Nanocrystal Assisted by Low‐Content Iridium for High‐Performance Flexible Electrode: Applications on Neural Interface, Water Oxidation, and Anti‐Microbial Contamination

“…One strategy is increasing the electrochemical surface area of the electrode to expand its electric double layer (EDL) capacitance, mainly including rough treatment (e.g., roughed Pt [23,24] ) and materials with large specific surface area (e.g., carbon nanotubes, [25,26] graphene, [27] etc. [28][29][30] ). However, most roughing methods are rather complex, for example, laser roughening for Pt.…”

Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

“…It was again noted that EDL:Ag 10:1 coated electrodes possess the highest CIC, greater than the CIC observed with both pristine EDL coated and bare Pt electrodes. Furthermore, among all investigated materials EDL:Ag 10:1 provided the most stable and controlled amount of injected charge, and the high CIC allows for the use of low electrical potentials without compromising the therapeutic effects of stimulation [ 45 ]. A comparison of the CIC values with respect to the AgNWs content in EDL:Ag composites indicated that lower AgNWs contents reduced the CIC, a phenomenon previously shown to be due to the lack of a robust percolation network [ 46 ], preventing the effective release of stored charge.…”

Controlled assembly of retinal cells on fractal and Euclidean electrodes

“…Their density, stiffness, and topography can be controlled [ 72 – 74 ], and they can be synthesized on, or transferred to, flexible substrates [ 75 , 76 ]. Due to a combination of their chemical composition and surface texture, CNTs promote neuronal adhesion and increase the number of processes and their growth [ 77 – 79 ]. Choosing from various topographies [ 80 , 81 ], we adopt a vertically-aligned CNT (VACNT) approach in which a conducting ‘forest’ of tangled CNTs is patterned on a smooth silicon dioxide (SiO 2 ) substrate.…”