Controlled, Rapid Deposition of Structured Coatings from Micro- and Nanoparticle Suspensions

Prevo, Brian G.; Velev, Orlin D.

doi:10.1021/la035295j

Cited by 490 publications

(562 citation statements)

References 57 publications

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“…If not all parameters are properly controlled multilayer or separated monolayer domains formation prevails. [57] 3.3.1.…”

Section: Vertical and Horizontal Deposition (Convective Assembly)mentioning

confidence: 99%

Surface Patterning with Colloidal Monolayers

Vogel

2012

Springer Theses

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This thesis focuses on the controlled assembly of monodisperse polymer colloids into ordered two-dimensional arrangements. These assemblies, commonly referred to as colloidal monolayers, are subsequently used as masks for the generation of arrays of complex metal nanostructures on solid substrates.The motivation of the research presented here is twofold. First, monolayer crystallization methods were developed to simplify the assembly of colloids and to produce more complex arrangements of colloids in a precise way. Second, various approaches to colloidal lithography are designed with the aim to include novel features or functions to arrays of metal nanostructures.The air/water interface was exploited for the crystallization of colloidal monolayer architectures as it combines a two-dimensional confinement with a high lateral mobility of the colloids that is beneficial for the creation of high long range order. A direct assembly of colloids is presented that provides a cheap, fast and conceptually simple methodology for the preparation of ordered colloidal monolayers. The produced two-dimensional crystals can be transformed into nonclose-packed architectures by a plasma-induced size reduction step, thus providing valuable masks for more sophisticated lithographic processes. Finally, the controlled co-assembly of binary colloidal crystals with defined stoichiometries on a Langmuir trough is introduced and characterized with respect to accessible configurations and size ratios.Several approaches to lithography are presented that aim at introducing different features to colloidal lithography. First, using metal-complex containing latex particles, the synthesis of which is described as well, symmetric arrays of metal nanoparticles can be created by controlled combustion of the organic material of the colloids. The process does not feature an inherent limit in nanoparticle size and is able to produce complex materials as will be demonstrated for FePt alloy particles. Precise control over both size and spacing of the particle array is presented.Second, two lithographic processes are introduced to create sophisticated nanoparticle dimer units consisting of two crescent shaped nanostructures in close proximity; essentially by using a single colloid as mask to generate two structures simultaneously. Strong coupling processes of the parental plasmon resonances of the two objects are observed that are accompanied by high near-field enhancements. A plasmon hybridization model is elaborated to explain all polarization dependent shifts of the resonance positions. Last, a technique to produce laterally patterned, ultra-flat substrates without surface topographies by embedding gold nanoparticles in a silicon dioxide matrix is applied to construct robust and re-usable sensing architectures and to introduce an approach for the nanoscale patterning of solid supported lipid bilayer membranes.

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“…If not all parameters are properly controlled multilayer or separated monolayer domains formation prevails. [57] 3.3.1.…”

Section: Vertical and Horizontal Deposition (Convective Assembly)mentioning

confidence: 99%

Surface Patterning with Colloidal Monolayers

Vogel

2012

Springer Theses

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“…Aqueous suspensions of surfactant-free sulfate-stabilized polystyrene latex spheres (diameter, D = 4.0, 5.7, and 8.7 µm ) were purchased from Interfacial Dynamics Corporation (OR). After centrifuging and washing with ultra-pure Milli-Q water the particles were concentrated and deposited in monolayers on pre-cleaned glass slides by our convective assembly method [20]. The top sides of the dried particle monolayers were coated with 10 nm of chromium followed by 20 nm of gold in a metal evaporator.…”

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confidence: 99%

Induced-Charge Electrophoresis of Metallodielectric Particles

et al. 2008

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The application of AC electric fields in aqueous suspensions of anisotropic particles leads to unbalanced liquid flows and nonlinear, induced-charge electrophoretic (ICEP) motion. We report experimental observations of the motion of "Janus" microparticles with one dielectric and one metal-coated hemisphere induced by uniform fields of frequency 100 Hz -10 kHz in NaCl solutions. The motion is perpendicular to the field axis and persists after particles are attracted to a glass wall. This phenomenon may find applications in microactuators, microsensors, and microfluidic devices.Nonlinear electrokinetic phenomena are widely used to manipulate colloids and drive flows in microfluidic devices. The liquid and particle velocities typically depend on the strength of the applied field squared and are commonly driven by alternating current (AC) to avoid Faradaic reactions. The classical example is dielectrophoresis (DEP), where a net electrostatic force causes particle motion in a non-uniform AC field. Polarization of the ionic double layers can also lead to nonlinear electro-osmotic flows at low frequencies (kHz), as first described by Murtsovkin and coworkers [1,2]. Bazant and Squires [3,4] conceptually unified this phenomenon with AC electro-osmosis at electrodes, first described by Ramos et al. [5] and Ajdari [6], and suggested the term "induced-charge electro-osmosis" (ICEO) to describe all flows resulting from the action of an applied electric field on its own induced diffuse charge near a polarizable surface. They also predicted how broken symmetries could cause polarizable particles to move in electric fields by "induced-charge electrophoresis" (ICEP) [3,7].

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“…In addition to substrate patterning, electrostatic [48], external electric field [49,50], floating self-assembly [51], centrifugation [52], filtration [53], and other methods [54][55][56] have all been investigated as a means for colloidal particle assembly. For example, in Figure 5 [51,52] there are examples of three-dimensional structure obtained from floating self-assembly and centrifugation, respectively.…”

Section: Surface Pattern-assisted Depositionmentioning

confidence: 99%