Laser-etch patterning of metal oxide coated carbon nanotube 3D architectures

Abstract

This paper describes a way to fabricate novel hybrid low density nanostructures containing both carbon nanotubes (CNTs) and ceramic nanotubes. Using atomic layer deposition, a thin film of aluminum oxide was conformally deposited on aligned multiwall CNT foams in which the CNTs make porous, three-dimensional interconnected networks. A CO laser was used to etch pure alumina nanotube structures by burning out the underlying CNT substrate in discrete locations via the printed laser pattern. Structural and morphological transitions during the calcination process of aluminum oxide coated CNTs were investigated through in situ transmission electron microscopy and high-resolution scanning electron microscopy. Laser parameters were optimized to etch the CNT away (i.e. etching speed, power and focal length) while minimizing damage to the alumina nanotubes due to overheating. This study opens a new route for fabricating very low density three dimensionally patterned materials with areas of dissimilar materials and properties. To demonstrate the attributes of these structures, the etched areas were used toward anisotropic microfluidic liquid flow. The demonstration used the full thickness of the material to make complex pathways for the liquid flow in the structure. Through tuning of processing conditions, the alumina nanotube (etched) regions became hydrophilic while the bulk material remained hydrophobic and electrically conductive.

Vertically Aligned Carbon Nanotube Microbundle Arrays for Field-Emission Applications

“…The frequency used in this experiment was 800 kHz, and the pulse width was 1 ns. Considering the divergence angle of the laser beam, , both positive and negative defocusing were used to ablate the VACNT film during the laser ablation processing, where the laser focal plane was just above or below the surface of the VACNT array film. The VACNT array film was ablated from the longitudinal and lateral directions, respectively, as shown in Figure .…”

Microfluidic Behavior of Alumina Nanotube-Based Pathways within Hydrophobic CNT Barriers

“…Fabrication of aluminum oxide-coated CNT foams and patterning of aluminum oxide nanotube channels within the CNT foams using laser etching method have been detailed elsewhere. 5 In summary, vertically aligned spinnable CNT arrays were grown on quartz substrates via chemical vapor deposition (CVD). The aligned CNT sheets were drawn from spinnable arrays and collected to make a uniform stack of CNT sheets.…”

“…Our previous work has reported the fabrication of aluminum oxide nanotube channels using a simple laser etching process. 5 By creating alumina nanotube channels within a hydrophobic CNT foam, the liquid flow is confined within the hydrophilic alumina channel. As such, the alumina nanotube channels transport liquids through capillary forces without the assistance of external forces.…”

“…Our previous work has reported the fabrication of aluminum oxide nanotube channels using a simple laser etching process . By creating alumina nanotube channels within a hydrophobic CNT foam, the liquid flow is confined within the hydrophilic alumina channel.…”