A flexible hydrophilic-modified graphene microprobe for neural and cardiac recording.
A graphene-based flexible microprobe developed by microelectromechanical system technology shows high resolution for the detection of electrophysiological signals from various bio-objects. The hydrophilization post-treatment using steam plasma was performed on the graphene surface to decrease the interfacial impedance between graphene and electrolyte, and thus improve the signal-to-noise ratio during neural and cardiac recording. The signal-to-noise ratio of the action potentials from axons of a crayfish measured by hydrophilic-modified graphene microprobe (27.8±4.0dB) is higher than that of untreated device (20.3±3.3dB). Also, the form of the QRS complex and T wave in the electrocardiogram of the zebrafish heart can be clearly distinguished using the modified device. The total measured noise levels of the overall stability of the system were 4.2μVrms (hydrophilic graphene) and 7.64μVrms (hydrophobic graphene). The graphene-based implant can be further used for in vivo, long-term recording and retina prosthesis.


BACKGROUND
In this study a graphene-based flexible microprobe developed using microelectromechanical system technology was demonstrated to enable high resolution detection of electrophysiological signals, including EKG in zebrafish models. Both hydrophilic and hydrophobic graphene were studied, paving the way to potential future clinical applications of this new technology.
Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan.
Chang-Hsiao
CH
Chen
Cheng-Te
CT
Lin
Wei-Lun
WL
Hsu
Yen-Chung
YC
Chang
Shih-Rung
SR
Yeh
Lain-Jong
LJ
Li
Da-Jeng
DJ
Yao
D000200:Action Potentials; D000818:Animals; D003400:Astacoidea; D017097:Electric Impedance; D004562:Electrocardiography / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry; D055724:Electrophysiological Phenomena; D006108:Graphite / Q000737:chemistry*; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008839:Microelectrodes; D059629:Signal-To-Noise Ratio; D015027:Zebrafish
D004573:Electrolytes; D006108:Graphite