Holey Films Research Articles

Holey films stand up to solvents and heat

Holey films stand up to solvents and heat

Topographical surface patterning with block copolymer stamps

We explore the potential of stamps of the block copolymer (BCP) polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP) for the parallel lithographic generation of topographic surface patterns taking advantage of the specific BCP properties. A first example includes additive surface manufacturing by decal transfer microcontact lithography with PS-b-P2VP breath figure (BF) arrays. Suppression of entanglements at the internal BCP domain interfaces and the BF array morphology facilitate rupture of the thinnest wall segments in the BF arrays. The uppermost PS-b-P2VP BF array layers with heights of nearly 1 µm thus remained attached to counterpart substrates. Treatment with solvents selective to PS or P2VP enabled wettability switching of thus-functionalized surfaces. A second example includes subtractive surface manufacturing. We deposited holey films or stripe patterns of the perfluorinated alkylphosphonic acid F21-DDPA on glass substrates using PS-b-P2VP stamps penetrated by spongy mesopore systems generated by swelling-induced pore formation. The use of spongy-mesoporous stamps allows carrying out succesive stamping steps without ink replenishment. Subsequently, we topographically patterned the glass substrates by etching the parts of the glass substrates not protected by F21-DDPA with hydrofluoric acid (HF) solution. Within certain limitations, shape, area and depth of the topographic patterns may be adjusted by the etching durations. Circular PS-b-P2VP films were selectively deposited into hexagonal microwells and subjected to swelling-induced pore formation. Moreover, F21-DDPA-patterned glass substrates can be used to template the dewetting of polystyrene (PS). Arrays of PS droplets obtained in this way were in turn used as etch resists to produce arrays of glass nanoneedles. Hence, BCP stamps may be exploited to produce topographically patterned surfaces with different architectures for wettability management or graphoepitaxy.

Nanocarbon Materials: Microcontact Printing with Laser Direct Writing Carbonization for Facile Fabrication of Carbon‐Based Ultrathin Disk Arrays and Ordered Holey Films (Small 44/2019)

Nanocarbon Materials: Microcontact Printing with Laser Direct Writing Carbonization for Facile Fabrication of Carbon‐Based Ultrathin Disk Arrays and Ordered Holey Films (Small 44/2019)

Microcontact Printing with Laser Direct Writing Carbonization for Facile Fabrication of Carbon-Based Ultrathin Disk Arrays and Ordered Holey Films.

A nanometer-thick carbon film with a highly ordered pattern structure is very useful in a variety of applications. However, its large-scale, high-throughput, and low-cost fabrication is still a great challenge. Herein, microcontact printing (µCP) and direct laser writing carbonization (DLWc) are combined to develop a novel method that enables ease of fabrication of nanometer-thick and regularly patterned carbon disk arrays (CDAs) and holey carbon films (HCFs) from a pyromellitic dianhydride-oxydianiline-based polyamic acid (PAA) solution. The effect of PAA concentration and pillar lattice structure of the polydimethyl siloxane stamp are systematically studied for their influence on the geometrical parameter, surface morphology, and chemical structure of the finally achieved CDAs and HCFs. Within the PAA concentration being investigated, the averaged thickness of CDAs and HCFs can be tailored in a range from a few tens to a few hundred of nanometers. The µCP+DLWc-enabled electrically conductive CDAs and HCFs possess the characteristics of ease-of-fabrication, nanometer-thickness, highly regular and controlled patterns and structures, and the ability to form on both hard and soft substrates, which imparts usefulness in electronics, photonics, energy storage, catalysis, tissue engineering, as well as physical, chemical, and bio-sensing applications.

Suspending samples over carbon holey films increases heterogeneity of molecular orientations in negative stain electron microscopy

Negative stain electron microscopy (NSEM) is a simple and cost effective method to analyze a wide variety of specimens, especially proteins. In traditional NSEM, the protein sample is applied to and supported by a continuous carbon film. Unfortunately, many proteins stick to the carbon film with a limited number of orientations. Because the restricted orientation limits the available views of the molecule, information about the three-dimensional structure of the molecule is likewise limited. The method presented here overcomes this limitation by using a carbon holey film combined with 1-octadecanol as a spreading agent. We demonstrate this method with solubilized envelope (Env) proteins from HIV, which typically show a restricted orientation on continuous carbon film, and show the following:•1-octadecanol added to negative stain aids the formation of a continuous sample-stain layer spanning the holes of a holey carbon film.•Samples negatively stained over holes show less restricted orientation, resulting in better single particle reconstructions.

Nickel Sulfide Freestanding Holey Films as Air-Breathing Electrodes for Flexible Zn-Air Batteries.

In this work, a combination of bottom-up electrochemical deposition and top-down electrochemical etching strategies followed by a subsequent sulfuration treatment was employed to rationally synthesize a nickel sulfide (NiS x) freestanding holey film (FHF). Owing to the holey structure along with the optimal electrochemically active surface area and active sites, the as-prepared NiS x FHF showed an impressive bifunctional electrocatalytic performance toward both oxygen evolution and reduction reactions. The holey and freestanding features provide the NiS x FHF with promising characteristics to be used as an ideal air-breathing cathode in flexible Zn-air batteries (ZABs). As a proof-of-concept, the rationally designed NiS x FHF achieved remarkable rechargeability and flexibility in a ZAB configuration.

Extraordinary optical transmission through nonlocal holey metal films

We investigate nonlocal electrodynamics based on the generalized hydrodynamic approach including electron diffusion in holey gold films, showing extraordinary optical transmission (EOT). Dramatic changes with respect to the local approximation for rather large film thicknesses t ≲ 100 nm impact both reflectance and absorbance at normal incidence. Beyond the familiar resonance blueshift with the decreasing film thickness, the interference of longitudinal pressure waves in the holey structure generates an unexpected oscillatory response with geometrical parameters. An increase in the transmittance relative to the local result of up to 33% (typically up to ±6% at resonance) was observed, but it can also be suppressed when absorption dominates. We expect that our findings will stimulate additional studies of EOT when taking into consideration nonlocal effects in holey films of experimentally accessible parameters in two-dimensional hole arrays.

Holey metal films: From extraordinary transmission to negative-index behavior

In this paper we study the common physical background of the phenomenon of extraordinary optical transmission in holey metal films and the emergence of the negative refractive index behavior in double fishnet structures. Here we provide further evidence that the resonant magnetic response of the latter structures is associated with the excitation of gap surface plasmon modes. The evolution of the optical response with the number of double fishnet layers is also addressed, finding that the effective refractive index reaches a converged value for a moderate number of layers.

Holey metal films make perfect endoscopes

Holey metal films make perfect endoscopes

Support Films with Uniform Hole Size

Abstract Holey carbon films mounted on standard EM grids are routinely used as specimen supports in electron cryo-microscopy, Adroplet of the sample containing, for example, a suspension of virus particles or protein molecules, is applied to the grid, blotted to a thin layer and rapidly frozen. The particles are then imaged where the liquid spans the holes, without interference from an underlying carbon support film. Many recipes for holey films have been presented in the literature, generaiiy employing some method of forming bubbles in a layer of solvent in which a material is dissolved that then forms a discontinuous layer as the solvent evaporates.

Easily prepared holey films for use in cryo‐electron microscopy

SummaryHoley films or nets may be produced from an emulsion of glycerol/water in a solution of a mixture of Formvar® and Triafol® in dichloromethane, spread on mica. After being floated off the mica support the films may be treated with ethyl acetate to transform ‘pseudoholes' into holes or nets.

CFM holey films

Chloroform-formvar-mica (CFM) can be used to make holey films in the simplest and most reliable procedure described to date. A wide variety of approaches have been devised to produce thin membranes with holes in them. Hayat (1978) provides an excellent historical overview of these perforated film techniques. They range from complex and cumbersome to relatively simple, but even these simpler techniques require either special solutions or incorporate time-dependent steps which may yield variable results. The CFM technique suffers from neither of these drawbacks; the steps are outlined below.Procedure:l. Dip a freshly cleaved mica strip into a 0.25% solution of formvar in chloroform and withdraw it at a slow, even rate. 2. Wick off excess solution, allow to dry for about one minute, and trim the formvar coated lower edges of the strip with scissors. 3. Score the formvar membrane with a razor blade just below the “high water mark” and float it onto distilled water.

Structure and crystallization of amorphous metal oxide films

High resolution electron microscopic observations have been made on amorphous and crystalline metal oxide films. The specimen films were prepared by vacuum-evaporation of metal oxide powder from alumina coated tungsten basket onto clean glass substrates at room temperature. The films were deposited to a thickness of 100 Å, monitored with quartz crystal oscillating microbalance. The films were wet-stripped from the substrates and then mounted on gold holey films which were supported by standard gold electron microscope grids. Transmission electron micrographs were taken with JEM 100-C electron microscope under axial illumination. The microscope was equipped with an objective lens with Cs=1.8 mm and operated at 100 kV.Figure 1 shows an electron micrograph and an electron diffraction pattern of as-deposited WO3 film. The thickness of the film is assumed to be less than 50 Å, since the 100 Å thick film was floated on the distilled water for 20 minutes for thinning by dissolution.

Formvar holey films and nets for electron microscopy.

A very quick, reliable and reproducible procedure for preparing 'holey' films with various ranges of hole diameters (0.05-20 mu m), as test objects for correction of astigmatism in high resolution instruments, and Formvar nets for mounting ultrathin microtome sections for high resolution electron microscopy is presented. It has been possible to control the hole diameter within limits under the stated conditions. The physical explanation for the mechanism of hole formation has also been given.

THE PREPARATION OF HOLEY FILMS FOR ELECTRON MICROSCOPY.

Vier verschiedene Methoden zur Gewinnung von Lochfolien für elektronenmikroskopische Belange werden beschrieben. Damit lassen sich unter anderem leicht Anzahl der Löcher pro Flächeneinheit und Lochdurchmesser variieren, so dass eine weitgehende Anpassung der Filmqualität an die sonstigen Versuchsbedingungen ermöglicht wird.

Holey films for electron microscopy.

VARIOUS methods have been described1 for the production of holey films required either for specimen support or astigmatism-correction purposes. Some of these methods are rather involved, and all can apparently produce pseudo-holes which are often difficult to detect and therefore very misleading.