Hydrophilic modification of neural microelectrode arrays based on multi-walled carbon nanotubes.
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.
Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan.
Chang-Hsiao
CH
Chen
Huan-Chieh
HC
Su
Shih-Chang
SC
Chuang
Shiang-Jie
SJ
Yen
Yung-Chan
YC
Chen
Yu-Tao
YT
Lee
Hsin
H
Chen
Tri-Rung
TR
Yew
Yen-Chung
YC
Chang
Shih-Rung
SR
Yeh
Da-Jeng
DJ
Yao
D000818:Animals; D003400:Astacoidea / Q000502:physiology; D058266:Dielectric Spectroscopy; D055664:Electrochemical Techniques / Q000295:instrumentation*; D057927:Hydrophobic and Hydrophilic Interactions; D008839:Microelectrodes; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D009474:Neurons / Q000502:physiology*; D056951:Photoelectron Spectroscopy; D013059:Spectrum Analysis, Raman; D017155:Wettability
D037742:Nanotubes, Carbon