Изготовление, уплотнения, и реплики Формование 3D микроструктур углеродных нанотрубок
Summary
Мы представляем методы изготовления узорные микроструктур вертикально углеродных нанотрубок (УНТ), и их использование в качестве ведущего пресс-форм для производства микроструктуры полимера с организованной наноразмерных текстуру поверхности. CNT леса уплотненным путем конденсации растворителя на подложке, что значительно увеличивает их плотность упаковки и позволяет самостоятельного формирования 3D-форм.
Abstract
The introduction of new materials and processes to microfabrication has, in large part, enabled many important advances in microsystems, lab-on-a-chip devices, and their applications. In particular, capabilities for cost-effective fabrication of polymer microstructures were transformed by the advent of soft lithography and other micromolding techniques 1, 2, and this led a revolution in applications of microfabrication to biomedical engineering and biology. Nevertheless, it remains challenging to fabricate microstructures with well-defined nanoscale surface textures, and to fabricate arbitrary 3D shapes at the micro-scale. Robustness of master molds and maintenance of shape integrity is especially important to achieve high fidelity replication of complex structures and preserving their nanoscale surface texture. The combination of hierarchical textures, and heterogeneous shapes, is a profound challenge to existing microfabrication methods that largely rely upon top-down etching using fixed mask templates. On the other hand, the bottom-up synthesis of nanostructures such as nanotubes and nanowires can offer new capabilities to microfabrication, in particular by taking advantage of the collective self-organization of nanostructures, and local control of their growth behavior with respect to microfabricated patterns.
Our goal is to introduce vertically aligned carbon nanotubes (CNTs), which we refer to as CNT “forests”, as a new microfabrication material. We present details of a suite of related methods recently developed by our group: fabrication of CNT forest microstructures by thermal CVD from lithographically patterned catalyst thin films; self-directed elastocapillary densification of CNT microstructures; and replica molding of polymer microstructures using CNT composite master molds. In particular, our work shows that self-directed capillary densification (“capillary forming”), which is performed by condensation of a solvent onto the substrate with CNT microstructures, significantly increases the packing density of CNTs. This process enables directed transformation of vertical CNT microstructures into straight, inclined, and twisted shapes, which have robust mechanical properties exceeding those of typical microfabrication polymers. This in turn enables formation of nanocomposite CNT master molds by capillary-driven infiltration of polymers. The replica structures exhibit the anisotropic nanoscale texture of the aligned CNTs, and can have walls with sub-micron thickness and aspect ratios exceeding 50:1. Integration of CNT microstructures in fabrication offers further opportunity to exploit the electrical and thermal properties of CNTs, and diverse capabilities for chemical and biochemical functionalization 3.
Protocol
Discussion
Литографических структурирование и подготовка CNT катализатор субстратов проста и повторяемые, однако, достижение устойчивого роста УНТ требует особого внимания к тому, как высота и плотность леса CNT подвергаются воздействию влажности окружающей среды и состояния роста трубки. По наш?…
Declarações
The authors have nothing to disclose.
Acknowledgements
Это исследование было поддержано нанопроизводства программы Национального научного фонда (CMMI-0927634). Давор Copic была частично поддержана стипендий Ракхем заслуги программе в Университете штата Мичиган. Самех Tawfick признает частичную поддержку от Ракхем Predoctoral стипендий. Майкл Де Volder при поддержке бельгийского фонда научных исследований – Фландрия (FWO). Микротехнологий проводилось на установке Лурье Nanofabrication (ЛНФ), которая является членом Национальной сетевой инфраструктуры нанотехнологий и электронной микроскопии была выполнена в Мичигане Электрон микропучка анализа лаборатории (Эмаль).
Materials
| Name of the reagent | Company | Catalogue number | Comments |
| 4″ diameter <100> silicon wafers coated with SiO2 (300 nm) | Silicon Quest | Custom | |
| Positive photoresist | MicroChem | SPR 220-3.0 | |
| Hexamethyldisilizane (HMDS) | MicroChem | ||
| Developer | AZ Electronic Materials USA Corp. | AZ 300 MIF | |
| Sputtering system | Kurt J. Lesker | Lab 18 | Sputtering system for catalyst deposition |
| Thermo-Fisher Minimite | Fisher Scientific | TF55030A | Tube furnace for CNT growth |
| Quartz tube | Technical Glass Products | Custom | 22 mm ID × 25 mm OD 30″ length |
| Helium gas | PurityPlus | He (PrePurified 300) | |
| Hydrogen gas | PurityPlus | H2 (PrePurified 300) | UHP |
| Ethylene gas | PurityPlus | C2H4 (PrePurified 300) | UHP |
| Perforated aluminum sheet | McMaster-Carr | 9232T221 | For holding sample above densification beaker |
| UV flood lamp | Dymax | Model 2000 | |
| SU-8 2002 | MicroChem | SU-8 2002 | |
| Polydimethylsiloxane (PDMS) | Dow Corning | Sylgard 184 Silicone Elastomer Kit |
Referências
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