3 डी कार्बन नैनोट्यूब Microstructures के निर्माण, densification, और प्रतिकृति मोल्डिंग
Summary
हम खड़ी गठबंधन कार्बन नैनोट्यूब (CNTs), और संगठित nanoscale सतह बनावट के साथ बहुलक microstructures के उत्पादन के लिए उनके गुरु molds के रूप में उपयोग के नमूनों की microstructures निर्माण के लिए तरीके प्रस्तुत करते हैं. CNT के जंगलों विलायक का संक्षेपण द्वारा सब्सट्रेट है, जो काफी उनके पैकिंग घनत्व बढ़ जाती है और 3 डी आकार का गठन आत्म निर्देशित सक्षम बनाता है पर densified कर रहे हैं.
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
Lithographic patterning और CNT के उत्प्रेरक substrates की तैयारी सरल और repeatable है, तथापि, कैसे ऊंचाई और CNT के जंगलों के घनत्व परिवेश नमी और विकास ट्यूब की हालत से प्रभावित कर रहे हैं संगत CNT के विकास को प्राप्त करने के लिए सावधान ध्य?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
इस अनुसंधान के राष्ट्रीय विज्ञान फाउंडेशन (CMMI 0,927,634) की nanomanufacturing कार्यक्रम के द्वारा समर्थित किया गया. Davor Copic भाग में मिशिगन विश्वविद्यालय में Rackham मेरिट फैलोशिप कार्यक्रम के द्वारा समर्थित किया गया. समेह Tawfick Rackham predoctoral फैलोशिप से आंशिक समर्थन मानता. फ़्लैंडर्स (FWO) – माइकल डी Volder के वैज्ञानिक अनुसंधान के लिए बेल्जियम फंड द्वारा समर्थित किया गया था. Microfabrication Lurie Nanofabrication (LNF) के सुविधा है, जो राष्ट्रीय नैनो इंफ्रास्ट्रक्चर नेटवर्क का एक सदस्य है पर प्रदर्शन किया था, और इलेक्ट्रॉन माइक्रोस्कोपी मिशिगन इलेक्ट्रॉन Microbeam विश्लेषण प्रयोगशाला (EMAL) में प्रदर्शन किया था.
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 |
Riferimenti
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