Maria Peter

Micromachined fountain pen for atomic force microscope-based nanopatterning

We present a tool that can be used in standard atomic force microscope and that enables chemical, chemical/mechanical, or physical surface modification using continuous liquid supply. The device consists of a reservoir micromachined into the probe support that is connected to fluidic channels embedded in a V-shaped cantilever. Via the fluidic channels, the liquid reaches the tip. The fluid transport to the sample surface is demonstrated and fountain pen lithography applications are presented.

Patterning the molecular printboard: patterning cyclodextrin monolayers on silicon oxide using nanoimprint lithography and its application in 3D multilayer nanostructuring

An accurate and versatile process for the fabrication of high-resolution 3D nanostructures combining top-down and bottom-up nanofabrication schemes is described here. The method is based on layer-by-layer (LBL) assembly of functionalized nanoparticles (NPs) bound together by means of supramolecular interactions between a layer of adamantyl-functionalized dendrimers, the guest, and cyclodextrin (CD)-functionalized nanoparticles, the host. First, a self-assembled CD monolayer (CD SAM) was patterned using nanoimprint lithography (NIL) and later used to anchor supramolecular LBL assemblies onto it. The versatility of the process was demonstrated by using NPs of different size and nature. Two types of LBL assemblies were fabricated based on (i) 2.8 nm CD-functionalized Au NPs, which allow an accurate height control and (ii) 60 nm CD-functionalized SiO2 particles, which permit the fabrication of nanostructures. In one of the cases vertical deposition was used to obtain high particle ordering. Both types of NP were used to produce nanostructured LBL assemblies with lateral sizes below 100 nm. Physical confinement was observed when using 60 nm CD-functionalized SiO2 particles in the sub-300 nm scale on the first and second bilayers. Finally, periodic patterns of single nanoparticles were achieved.

Fabrication and visualization of metal-ion patterns on glass by dip-pen nanolithography.

Fluorescent self-assembled monolayers (SAMs) are used as dip-pen nanolithography (DPN) substrates for the fabrication of patterns of Ca(2+) and Cu(2+) ions. The driving force for the transfer of these ions from an atomic force microscopy (AFM) tip to the surface is their complexation to organic ligands on the monolayer. By means of fluorescent surfaces, the patterns can be visualized under a fluorescence microscope. We use a custom-built atomic force fluorescence microscope (AFFM), a combination of atomic force and confocal fluorescence microscopes, to deposit the metal ions onto the sensing SAMs by DPN and to subsequently visualize modulations of fluorescence intensity in a sequential write-read mode.

Electrochemical AFM on surface grafted poly(ferrocenylsilanes)

Ethylenesulfide and trimethylenesulfide end-functionalized poly(ferrocenyldimethylsilanes) (ES-PFS and TMS-PFS) with different degrees of polymerization were prepared via anionic ring-opening polymerization. Molecular characterization of ES-PFS was carried out by using 1H-NMR, GPC, FTIR, and elemental analysis. Thin films of ES-PFS were prepared by immersing gold(111) substrates into 1.0 mg/ml solutions of the polymers in toluene. The polymeric films were characterized by FTIR, XPS, and contact angle measurements. Thicknesses of the grafted films were measured by SPR. Thicknesses determined by SPR and the theoretically calculated values are in a reasonable agreement. The morphology of the films was studied by tapping mode AFM. The electrochemical behavior of the films was monitored by cyclic voltammetry (CV). CVs show two reversible redox peaks, indicating a stepwise oxidation of the iron atoms in the polymer chains. Scanning Electrochemical Force Microscopy (SEFM) allowed us to study in situ the morphological changes occurring in the film upon electrochemical oxidation or reduction. AFM images indicated that in the oxidized form the chains were stretched due to electrostatic repulsion.

Double-layer imprint lithography on wafers and foils from the submicrometer to the millimeter scale.

In this paper, a thermal imprint technique, double-layer nanoimprint lithography (dlNIL), is introduced, allowing complete filling of features in the dimensional range of submicrometer to millimeter. The imprinting and filling quality of dlNIL was studied on Si substrates as a model system and compared to results obtained with regular NIL (NIL) and reverse NIL (rNIL). Wavy foils were imprinted with NIL, rNIL and dlNIL and the patterning results compared and discussed. With dlNIL, a new application possibility was introduced in which two different resists having, for example, a different etch resistance to a certain plasma were combined within one imprint step. dlNIL allows extension to many resist combinations for tailored nanostructure fabrication.

Silver Containing Nanostructures from Hydrogen-bonded Supramolecular Scaffolds

The self-organisation of silver-containing hydrogen-bonded rosette assemblies on highly oriented pyrolytic graphite (HOPG) surfaces is described. The introduction of silver atoms into the double rosette architecture was achieved using the affinity of silver cations for cooperative π-donors or cyano functionalities on the double rosettes. Highly ordered 2-D nanorod domains with an inter-row spacing of 4–5 nm oriented in different directions were revealed by tapping-mode atomic force microscopy (AFM). This new and simple strategy for the creation of metal-containing supramolecular nanorod arrays that can act as well-defined surface-immobilised self-assembled scaffolds, will contribute to the development of functionalised nanoarchitectures via bottom–up approaches.