Summary

Изготовление, уплотнения, и реплики Формование 3D микроструктур углеродных нанотрубок

Published: July 02, 2012
doi:

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

1. Catalyst структурирование Приобретать (100) кремниевых пластин с 3000A толстым слоем диоксида кремния, по крайней мере одной полированной стороной. Кроме того, вы можете приобрести голый кремниевой пластины и расти 3000A диоксида кремния на подложке. Вся обработка описаны ниже делается н…

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?…

Disclosures

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  

References

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Cite This Article
Copic, D., Park, S. J., Tawfick, S., De Volder, M., Hart, A. J. Fabrication, Densification, and Replica Molding of 3D Carbon Nanotube Microstructures. J. Vis. Exp. (65), e3980, doi:10.3791/3980 (2012).

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