| 초록 |
Carbon nanotubes (CNTs) have shown superior intrinsic properties attractive for various potential application. By creating nanostructures, it is possible to control the fundamental properties of materials even without changing the materials' chemical composition. Novel methods to assemble CNTs into hierarchical arrays with controllable shape, location, orientation, and density are needed. Three types of hierarchical and multifunctional three-dimensional (3D) carbon nanotube structures have been developed for various applications. The first type is 3D-network of CNTs (3DNC) structures which comprised of suspended and interconnected CNTs between Si pillars. The second and third types are highly ordered CNT walls assisted by Si pillar arrays and open-cell like CNT structure, respectively, and these two types were obtained by capillary force driven self-assembly. Limited by the graphitic surface structure of CNTs and pillar structure, the surface of 3D CNTs is hydrophobic so that its applications are limited. Non-covalent surface modification methods, like physical vapor depositions, chemical vapor depositions, electrochemical depositions and polymer coatings, are used to functionalize the 3D CNTs. For instance, the 3DNC is coaxially coated with Al2O3 by atomic layer deposition process to prevent the undesired aggregation or breaking of suspended CNTs in a microfluidic filtration chip, and this Al2O3 coated 3DNC can be functionalized by surface modification as a biosensor platform for the detection of cancer biomarkers and surfactin-producing bacterial strains with high sensitivity. A color sensor platform immobilized with polydiacetylene vesicles on 3D CNTs structures shows an excellent sensitivity with selectivity enhancement for cyclodextrin recognition. Another example of flexible strain sensors based on CNTs will be introduced. |
