Fabrication of High Aspect Ratio Millimeter-Tall Free-Standing Carbon Nanotube-Based Microelectrode Arrays

Abstract

Microelectrode arrays of carbon nanotube (CNT)/carbon composite posts with high aspect ratio and millimeter-length were fabricated using carbon-nanotube-templated microfabrication with a sacrificial “hedge”. The high aspect ratio, mechanical robustness, and electrical conductivity of these electrodes make them a potential candidate for next-generation neural interfacing. Electrochemical measurements were also demonstrated using an individual CNT post microelectrode with a diameter of 25 μm and a length of 1 mm to perform cyclic voltammetry on both methyl viologen and dopamine in a phosphate-buffered saline solution. In addition to detection of the characteristic peaks, the CNT post microelectrodes show a fast electrochemical response, which may be enabling for in vivo and/or in vitro measurements. The CNT post electrode fabrication process was also integrated with other microfabrication techniques, resulting in individually addressable electrodes.

Influence of Carbon Nanotube Attributes on Carbon Nanotube/Cu Composite Electrical Performances

“…MW-CNTW templates show >96 wt % CNTs and catalyst residues < 1 wt % in air-TGA carried out from room temperature to 1000 • C, as reported in our earlier studies [8,10,11]. As mentioned in the experimental section, SW-CNTPs were obtained by water-assisted CVD, which is known to result in CNT materials of high purity with low catalyst residues [7,28,29]. Gas-phase carbon deposition was carried out on SW-CNTPs after CVD synthesis to include amorphous carbon in between nanotubes and nanotube bundles to retain pillar structural integrity during electrodeposition.…”

“…Typical CNTW linear densities were ≈ 7-9 × 10 −4 mg/mm. The SW-CNTPs were synthesized in-house by "supergrowth" (water-assisted CVD) on Si substrates, as described previously [7,28,29]. Arrays of pillars (diameter ≈ 100 µm, spaced ≈ 200 µm apart, pillar length and CNT length ≈ 300 µm, 95-98% porosity) were grown upon lithographically patterned CVD catalyst (≈3 nm thick Fe/40 nm thick Al 2 O 3 buffer) deposited on patterned W lines (Figure S1, Supplementary Materials).…”

Emerging Internet of Things driven carbon nanotubes-based devices

“…Also, the actuation based on CNT/elastic polymer-based composite has been reported [323,324]. Besides, neural interfacing [325][326][327] bridges the brains and the artificial sensory devices through microelectrode arrays [328][329][330] and neuronal signaling [331] and neural recording [332,333].…”

Low temperature growth of carbon nanotubes – A review

“…A unique capability of CVD method is that both vertical and horizontally aligned CNTs at predefined substrate locations can be grown (Fig. 5), which allows their direct integration in various applications, for example, interconnects, micro-electrode arrays and optical devices [37,79,91,102,[105][106][107][108][109][110][111]. Selective growth of metallic (m-SWCNTs) or semiconducting (s-SWCNTs) CNTs with controlled diameter, walls, chirality, alignment and density is still challenging.…”