Advanced Materials

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Special Issue: Soft Lithography, dedicated to George M. Whitesides

August, 2004

Volume 16, Issue 15

Pages 1235–1378

    1. Inside Cover Adv. Mater. 15/2004 (page 1235)

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200490043

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      Soft Lithography and the Art of Patterning — A Tribute to Professor George M. Whitesides (pages 1245–1246)

      Y. Xia

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400834

      This special issue of Advanced Materials has been put together in honor of the 65th birthday of Professor George Whitesides. A very brief outline of his work, along with a summary of the contributions to the issue are provided in this Guest Editorial.

    3. Patterning: Principles and Some New Developments (pages 1249–1269)

      M. Geissler and Y. Xia

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400835

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      Patterning is of paramount importance in many areas of modern science and technology. In this review, three broad aspects are discussed: strategies for generating patterns from scratch; duplication and transfer of patterns from the surface of a mask or master into other functional materials (see Figure); and, briefly, methods for generating (and replicating) certain types of three-dimensional structures.

    4. Form and Function in Multilayer Assembly: New Applications at the Nanoscale (pages 1271–1293)

      P. T. Hammond

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400760

      Layer-by-layer assembly is an approach based on the alternating adsorption of materials containing complementary charged or functional groups to form integrated ultrathin films, with nanometer-level control of film composition and structure. Many new shapes and functions made accessible at nanometer to mesoscopic length scales using this unique, low-cost approach to nanofabrication, as well as new functionalities incorporated within these materials, and new means of patterning and templating these structures in two and three dimensions, are reviewed.

    5. Crystallization in Patterns: A Bio-Inspired Approach (pages 1295–1302)

      J. Aizenberg

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400759

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      A potent methodology to materials engineering is offered by the ability to construct periodic arrays of uniform oriented single crystals, large single crystals with controlled microporosity, or films presenting patterns of crystals (see Figure). Bio-inspired approaches to artificial crystallization based on the use of organized organic surfaces patterned with specific initiation domains on a sub-micrometer scale are surveyed here.

    6. Micropatterned Environments in Cell Biology (pages 1303–1313)

      S. Raghavan and C. S. Chen

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400594

      Microfabrication and materials-science-based approaches provide a powerful new set of tools to control the spatial organization and temporal presentation of cellular cues. In this progress report, recent advances in the technological development and application of these tools to study how cells sense and respond to their microenvironment are highlighted.

    7. Precise Control over Molecular Dimensions of Block-Copolymer Domains Using the Interfacial Energy of Chemically Nanopatterned Substrates (pages 1315–1319)

      E. W. Edwards, M. F. Montague, H. H. Solak, C. J. Hawker and P. F. Nealey

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400763

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      Epitaxial assembly of block-copolymer films (see Figure) onto chemically nanopatterned substrates results in arrays of nanoscopic domains that are defect-free, oriented, and registered with the underlying substrate. The range of dimensions of features (or periodicity of structures) that can be patterned with perfection and registration strongly depends on the interfacial energy between the substrate and the polymer film.

    8. Rapid Prototyping of Microstructures with Bell-Shaped Cross-Sections and Its Application to Deformation-Based Microfluidic Valves (pages 1320–1323)

      N. Futai, W. Gu and S. Takayama

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400595

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      Rapid prototyping of microchannels with bell-shaped (as opposed to rectangular) cross-sections (see Figure) is reported. These microchannels are ideal for deformation-based microfluidic valving using piezoelectric vertical actuator arrays in refreshable Braille displays. The fabrication method is based on diffused backlight exposure with a transilluminator and is cost and time efficient.

    9. Patterning of Thin-Film Microstructures on Non-Planar Substrate Surfaces Using Decal Transfer Lithography (pages 1323–1327)

      W. R. Childs and R. G. Nuzzo

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400592

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      Soft-lithographic patterning of thin-film material microstructures supported on spherically curved lenses (see Figure) using an extension of decal transfer lithography (DTL) is reported. These processes have been used to successfully create a pattern of amorphous silicon and gold thin-film microstructures with feature sizes ranging from 2 μm to 75 μm. This has been achieved without noticeable defects using wet and reactive-ion etching processes across large substrate areas.

    10. Quasi-2D Polymer Objects from Patterned, Crosslinked Polymer Brushes (pages 1327–1331)

      S. Edmondson and W. T. S. Huck

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400761

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      Polymer sheets (see Figure) with nanometer-scale thicknesses, micrometer-scale lateral dimensions, and interesting materials properties that could be exploited in applications such as polymeric nanoactuators, biomimetic systems, and drug delivery vehicles have been fabricated via a new approach. The method employs crosslinked polymer brushes supported on micropatterned surfaces and subsequent electrolytic lifting.

    11. Patterned Orientations of Liquid Crystals on Affinity Microcontact Printed Proteins (pages 1331–1336)

      M. L. Tingey, E. J. Snodgrass and N. L. Abbott

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400758

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      The patterning of the orientations of liquid crystals on surfaces decorated with proteins using microcontact and “affinity” microcontact printing is reported (see Figure). The direction of contact between the stamp and surface during printing of the proteins defines the orientation of the printed proteins determines the alignment of the liquid crystal.

    12. Fabrication of Magnetic FePt Patterns from Langmuir–Blodgett Films of Platinum–Iron Oxide Core–Shell Nanoparticles (pages 1337–1341)

      Q. Guo, X. Teng and H. Yang

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400596

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      The patterned Langmuir–Blodgett (pLB) technique has been used to generate micrometer-sized structures of Pt@Fe2O3 core–shell nanoparticles. The composition of these core–shell nanoparticles has been further converted in situ into face-centered tetragonal phase FePt, one of the best candidates for ultra-high-density magnetic-storage media without loss of the pattern (see Figure).

    13. Templated and Hierarchical Assembly of CdSe/ZnS Quantum Dots (pages 1341–1345)

      Y. Babayan, J. E. Barton, E. C. Greyson and T. W. Odom

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400764

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      CdSe/ZnS nanocrystals have been assembled into mesoscale structures (see Figure). Templates with dimensions down to 100 nm are generated via phase-shifting photolithography using composite poly(dimethylsiloxane) masks. Upon removal of the template, the CdSe/ZnS structures are found to exhibit hierarchical order over square nanometers (self-assembly of nanocrystals), square micrometers (template shape), and square centimeters (arrays of template pattern).

    14. Fabrication of Collagen Gels That Contain Patterned, Micrometer-Scale Cavities (pages 1345–1348)

      M. D. Tang, A. P. Golden and J. Tien

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400766

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      A procedure for fabricating collagen gels that contain patterned cavities is described. The fabricated collagen gel consists of cells that are localized at the surfaces of an array of cavities. It was found that an introduction of flow through the collagen and cavities enhanced the exchange of materials between the cavities and the surrounding gel (see Figure). It is believed that this work will enable the in-vitro fabrication of structures that mimic the geometry of epithelial tissues.

    15. Directed Growth of Ordered Arrays of Small-Diameter ZnO Nanowires (pages 1348–1352)

      E. C. Greyson, Y. Babayan and T. W. Odom

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400765

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      Array growth of small-diameter (10–15 nm) zinc oxide (ZnO) nanowires by patterning and template-directed growth methods is reported. The ZnO nanowire arrays (see Figure) were patterned over large areas (∼1 cm2), and exhibited photoluminescence—a characteristic of highly crystalline materials.

    16. Electroactive Substrates that Reveal Aldehyde Groups for Bio-Immobilization (pages 1352–1356)

      W. S. Yeo and M. Mrksich

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400591

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      An electroactive substrate (see Figure) that reveals aldehyde groups in response to an oxidative potential is reported. The process is based on monolayers that can be switched to initiate the selective immobilization of an amino functionalized ligand, and marks a significant advance over previous dynamic substrates that have initiated the immobilization of a ligand, since it reveals a functional group that does not require labelling of a ligand.

    17. Using Soft Lithography to Pattern Highly Oriented Polyacetylene (HOPA) Films via Solventless Polymerization (pages 1356–1359)

      H. Gu, R. Zheng, X. Zhang and B. Xu

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400768

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      A new application of the combination of soft lithography and solventless polymerization is described (see Figure)—the patterning of ultra-hard microstructures in selected areas using highly oriented polyacetylene (HOPA) films as a precursor. It is expected that this simple, low-cost, and mild process will lead to the formation of highly oriented films of other materials, e.g., electro-optically active polymers.

    18. Colloidal Crystals Grown on Patterned Surfaces (pages 1360–1364)

      M. Allard, E. H. Sargent, P. C. Lewis and E. Kumacheva

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400762

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      Colloidal crystals grown onto patterned substrates (see Figure) are characterized by microscopic imaging, optical diffraction, and, most effectively, laser diffraction. The surface pattern imposes a common, predetermined lattice orientation which extends to the entire thickness of the crystal, offering a promising bottom–up approach to the fabrication of photonic crystals.

    19. Formation of Arrayed Droplets by Soft Lithography and Two-Phase Fluid Flow, and Application in Protein Crystallization (pages 1365–1368)

      B. Zheng, J. D. Tice and R. F. Ismagilov

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400590

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      Soft lithography and two-phase fluid flow have been used in order to form arrays of droplets (see Figure). Glass capillaries could be coupled to the poly(dimethylsiloxane) (PDMS) microchannels and droplets could be transferred into glass capillaries for long-term storage. The arrays of droplets have been applied to screen the conditions for protein crystallization with microbatch and vapor diffusion techniques.

    20. Three-Dimensional Nanofabrication with Rubber Stamps and Conformable Photomasks (pages 1369–1373)

      S. Jeon, E. Menard, J.-U. Park, J. Maria, M. Meitl, J. Zaumseil and J. A. Rogers

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400593

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      Two recently developed soft- lithographic techniques that have the capability to pattern 3D nanostructures are described. Nanotransfer printing relies on the transfer of thin solid coatings from rubber stamps, whilst proximity field nanopatterning uses these stamps for patterning of thin layers of photopolymers. The techniques are simple, can be used to form complex 3D nanostructures over large areas quickly, and provide much flexibility in the geometry of structures (see Figure) that can be formed.

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      Whitesides' Group: Writing a Paper (pages 1375–1377)

      G. M. Whitesides

      Version of Record online: 25 AUG 2004 | DOI: 10.1002/adma.200400767

      Insights into conducting research and the writing of scientific papers are given by Prof. Whitesides in this short essay. The manuscript and its guidelines has been circulated within the Whitesides' research group since 1989.