Hydrophilic modification of neural microelectrode arrays based on multi-walled carbon nanotubes

Abstract

To decrease the impedance of microelectrode arrays, for neuroscience applications we have fabricated and tested MEA based on multi-walled carbon nanotubes. With decreasing physical size of a microelectrode, its impedance increases and charge-transfer capability decreases. To decrease the impedance, the effective surface area of the electrode must generally be increased. We explored the effect of plasma treatment on the surface wettability of MWCNT. With a steam-plasma treatment the surface of MWCNT becomes converted from superhydrophobic to superhydrophilic; this hydrophilic property is attributed to -OH bonding on the surface of MWCNT. We reported the synthesis at 400 °C of MWCNT on nickel-titanium multilayered metal catalysts by thermal chemical vapor deposition. Applying plasma with a power less than 25 W for 10 s improved the electrochemical and biological properties, and circumvented the limitation of the surface reverting to a hydrophobic condition; a hydrophilic state is maintained for at least one month. The MEA was used to record neural signals of a lateral giant cell from an American crayfish. The response amplitude of the action potential was about 275 µV with 1 ms period; the recorded data had a ratio of signal to noise up to 40.12 dB. The improved performance of the electrode makes feasible the separation of neural signals and the recognition of their distinct shapes. With further development the rapid treatment will be useful for long-term recording applications.

IL-1R signalling is critical for regulation of multi-walled carbon nanotubes-induced acute lung inflammation in C57Bl/6 mice

“…Inexpensive nickel catalyst is being used to generate the large volumes of MWCNT currently in high market demand (Chen et al 2010). Nickel-associated MWCNT are in use as supercapacitor electrodes in hybrid automobiles and solar panels (Gao et al 2008; Lang et al 2008; Nam et al 2008).…”

Coatings of Different Carbon Nanotubes on Platinum Electrodes for Neuronal Devices: Preparation, Cytocompatibility and Interaction with Spiral Ganglion Cells

“…The CNT coatings lead to more than tenfold higher capacitances of the electrodes (300–600 μF∙cm −2 ) compared to uncoated platinum electrodes (20–30 μF∙cm −2 ), with the films containing single-wall nanotubes having twice higher values than those prepared from multi-wall nanotubes. Although the decrease of the impedance due to the CNT coating and the resultant higher capacitances of the CNT-coated electrodes were clearly evident, even larger reductions of impedances were reported from other research groups for electrode modification methods with CNTs [ 10 , 37 ]. However, these results refer to small electrodes where the initial impedances of the uncoated electrodes are very high.…”

Spectroelectrochemical monitoring of contaminants during the electrochemical filtration process using free-standing carbon nanotube filters

“…Although different methods can be followed to obtain hydrophilic carbon nanostructures [56,57] our interest is focused on the electrochemical route because this procedure is cleaner and faster [58][59][60]. Typically, the oxidation of carbon nanotubes introduces functional groups (hydroxyl, carbonyl, carboxyl or epoxide groups) into the molecular structure, providing hydrophilic properties to carbon structures [61].…”