Four probe architecture using high spatial resolution single multi-walled carbon nanotube electrodes for electrophysiology and bioimpedance monitoring of whole tissue

Asis, Edward D. de; Leung, Joseph; Wood, S.L.; Nguyen, Cattien V.

doi:10.1063/1.3292216

Cited by 1 publication

(1 citation statement)

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“…However, EI measurement has not yet been realized, due to the difficulty of fabricating the electrode, especially the insulation. For example, Asis et al measured the EI of CNT probes without insulation for the electrical stimulation and recording of muscle fibers [12][13][14]. Due to the imbalance of surface area between the CNTs and the probe support structures, most of the measured EI may be attributed to the EI of the support structures rather than to that of the CNTs.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical impedance measurement of a carbon nanotube probe electrode

et al. 2012

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We measured and analyzed the electrochemical impedance of carbon nanotube (CNT) probe electrodes fabricated through the physical separation of insulated CNT bridges. The fabricated CNT electrodes were free-standing CNTs that were completely covered with an insulator, except for their tips. Typical dimensions of the nanoelectrodes were 1-10 nm in CNT diameter, 80-300 nm in insulator diameter, 0.5-4 μm in exposed CNT length and 1-10 μm in probe length. The electrochemical impedance at frequencies ranging from 40 Hz to 1 MHz was measured in physiological saline. The measured impedance of the CNT electrode was constant at 32 MΩ at frequencies below 1 kHz and was inversely proportional to frequency at frequencies above 10 kHz. By means of comparison with the parasitic capacitive impedance of the insulator membrane, we confirmed that the electrode was sufficiently insulated such that the measured constant impedance was given by the exposed CNT tip. Consequently, we can use the CNT electrode for highly localized electrochemical impedance measurements below 1 kHz. Considering an equivalent circuit and the nanoscopic dimensions of the CNT electrode, we demonstrated that the constant impedance was governed by diffusion impedance, whereas the solution resistance, charge-transfer resistance and double-layer capacitance were negligible.

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Section: Introductionmentioning

confidence: 99%