Carbon Nanotube Microelectrode Assembly for Electrochemical Sensors

摘要

Assembling carbon nanotubes (CNTs) into macroscopic materials allows multiple applications that take advantage of their unique physical properties. Specifically, the synthesis, fiber assembly, polymer coating and application of CNTs as microelectrodes in electrochemical detection and quantification of heavy metals and neurotransmitters will be presented. CNT microelectrodes has been found to detect subnanomolar concentrations of Pb, Hg, Cd and Cu simultaneously. Excellent limits of detection of neurotransmitters (in the range of ～10~(-11)M) such as dopamine (DA), serotonin (5-HT), epinephrine (Epn) and nor-epinephrine (Nor-epn) have been observed when using voltammetric techniques. As a proof of practical application, microelectrodes have been tested in real time DA release from culture rat pheochromocytoma (PC12) cells upon concentrate K~+stimulation. In addition, the microelectrodes have been tested for recordings and stimulations of neuron electrical activity that is a topic of great interest in neuroscience. Multiple neurological disorders can benefit from a microelectrode that is flexible, chemically inert, electrically conducting, and preferentially transfers electrons via capacitive charge-injection. We compare the electron transfer capabilities among CNT fiber, noble metals Au and Ag wire microelectrodes when connected biological tissue. The recording ability of microelectrodes is demonstrated through Electroretinography (ERG) on Sarcophaga bullata fly eyes (Fig 1, left), where light stimulation generates potential changes that were detected by our microelectrodes. Stimulation is demonstrated through Au wire and carbon nanotube fiber implants in Madagascar hissing cockroach (Gromphadorhina portentosa) antennas (Fig 1, right) to control their locomotion directions. Interface Impedance, charge injection capacity and electrical conductivity of CNT microelectrodes demonstrates their potential in neuroscience applications.