Ralf Jede

Dynamics of completely unfolded and native proteins through solid-state nanopores as a function of electric driving force.

We report experimentally the dynamic properties of the entry and transport of unfolded and native proteins through a solid-state nanopore as a function of applied voltage, and we discuss the experimental data obtained as compared to theory. We show an exponential increase in the event frequency of current blockades and an exponential decrease in transport times as a function of the electric driving force. The normalized current blockage ratio remains constant or decreases for folded or unfolded proteins, respectively, as a function of the transmembrane potential. The unfolded protein is stretched under the electric driving force. The dwell time of native compact proteins in the pore is almost 1 order of magnitude longer than that of unfolded proteins, and the event frequency for both protein conformations is low. We discuss the possible phenomena hindering the transport of proteins through the pores, which could explain these anomalous dynamics, in particular, electro-osmotic counterflow and protein adsorption on the nanopore wall.

Exploration of the ultimate patterning potential achievable with focused ion beams.

Decisive advances in the field of nanosciences and nanotechnologies are intimately related to the development of new instruments and of related writing schemes and methodologies. Therefore we have recently proposed the exploitation of the nano-structuring potential of a highly focused ion beam (FIB) as a tool, to overcome intrinsic limitations of current nano-fabrication techniques and to allow innovative patterning schemes that are urgently needed in many nanoscience challenges. In this work, we will first detail a very high-resolution FIB instrument we have developed specifically to meet these nano-fabrication requirements. Then we will introduce and illustrate an advanced FIB processing scheme that is the fabrication of artificial nanopores.

Multispecies focused ion beam lithography system and its applications

The authors present a focused ion beam lithography (IBL) instrument and its extension toward using different ion species beyond gallium. The base instrument utilizes a lithography architecture and an ion source and column dedicated to nanofabrication. This includes large area navigation and patterning by a laser interferometer stage, long-term beam to sample positional as well as beam current stability and automation capabilities. Since the ion type can have dramatic consequences on the resulting nanostructures, the authors have extended the gallium IBL tools ion column and source toward the stable delivery of multiple species for a nanometer scale focused ion beam based on a liquid metal alloy ion source. The IBL system is equipped with an E × B mass filter capable of selecting different single and multiple charged ion species, simultaneously originating from the same source. The authors investigated different AuSi or AuGe based sources and in particular an ion source delivering Au, Si and Be focused io...

Fixed Beam Moving Stage electron beam lithography of waveguide coupling device structures

The Fixed Beam Moving Stage (FBMS) lithography mode is used toward the fabrication of waveguide coupling device structures. Scanning electron microscope metrology is used for the dimensional characterization of the resulting waveguide structures.

Direct FIB fabrication and integration of “single nanopore devices” for the manipulation of macromolecules

Here we propose to detail an innovative FIB instrumental approach and processing methodologies we have developed for sub-10 nm nanopore fabrication. The main advantage of our method is first to allow direct fabrication of nanopores in relatively large quantities with an excellent reproducibility. Second our approach offers the possibility to further process or functionalize the vicinity of each pore on the same scale keeping the required deep sub-10 nm scale positioning and patterning accuracy. We will summarise the optimisation efforts we have conducted aiming at fabricating thin (10-100 nm thick) and high quality dielectric films to be used as a template for the nanopore fabrication, and at performing efficient and controlled FIB nanoengraving of such a delicate media. Finally, we will describe the method we have developed for integrating these “single nanopore devices” in electrophoresis experiments and our preliminary measurements.

First Results From A Multi-Ion Beam Lithography And Processing System At The University Of Florida

The University of Florida (UF) have collaborated with Raith to develop a version of the Raith ionLiNE IBL system that has the capability to deliver multi‐ion species in addition to the Ga ions normally available. The UF system is currently equipped with a AuSi liquid metal alloy ion source (LMAIS) and ExB filter making it capable of delivering Au and Si ions and ion clusters for ion beam processing. Other LMAIS systems could be developed in the future to deliver other ion species. This system is capable of high performance ion beam lithography, sputter profiling, maskless ion implantation, ion beam mixing, and spatial and temporal ion beam assisted writing and processing over large areas (100 mm2)—all with selected ion species at voltages from 15–40 kV and nanometer precision. We discuss the performance of the system with the AuSi LMAIS source and ExB mass separator. We report on initial results from the basic system characterization, ion beam lithography, as well as for basic ion‐solid interactions.

Tailoring nanopores for efficient sensing of different biomolecules

Highly Focused Ion Beams (FIB) are used to produce in one step large quantities of solid state nanopores drilled in thin dielectric films with high reproducibility and well controlled morphologies. We explore both the production of nanopores of various diameters and study their applicability to different biological molecules such as DNA, or folded and unfolded proteins, and then we compare their transport properties. We also report on the translocation of Fibronectin which an original experiment made possible is using the methodology described in this article.

Exploration of the Ultimate Patterning Potential Achievable with Focused Ion Beams

Decisive advances in the fields of nanosciences and nanotechnologies are intimately related to the development of new instruments and of related writing schemes and methodologies. Therefore we have recently proposed exploitation of the nano-structuring potential of a highly Focused Ion Beam as a tool, to overcome intrinsic limitations of current nano-fabrication techniques and to allow innovative patterning schemes urgently needed in many nanoscience challenges. In this work, we will first detail a very high resolution FIB instrument we have developed specifically to meet these nano-fabrication requirements. Then we will introduce and illustrate some advanced FIB processing schemes. These patterning schemes are (i) Ultra thin membranes as an ideal template for FIB nanoprocessing. (ii) Local defect injection for magnetic thin film direct patterning. (iii) Functionalization of graphite substrates to prepare 2D-organized arrays of clusters. (iv) FIB engineering of the optical properties of microcavities.

Review Article: Review of electrohydrodynamical ion sources and their applications to focused ion beam technology

In this article, the authors review, compare, and discuss the characteristics and applicative potential of a variety of nongallium ion liquid metal ion sources they have developed and successfully applied to nanopatterning. These sources allow generating on-demand ion beams and are promising for extending focused ion beams applications. They detail the operating characteristics of such sources capable to emit metal projectiles ranging from atomic ions with different charge states to polyatomic ions and to large metal clusters having sizes up to a few nanometers. They highlight their interest and relevance to current nanoscience challenges in terms of ultimate patterning or bottom-up nanofabrication capabilities.In this article, the authors review, compare, and discuss the characteristics and applicative potential of a variety of nongallium ion liquid metal ion sources they have developed and successfully applied to nanopatterning. These sources allow generating on-demand ion beams and are promising for extending focused ion beams applications. They detail the operating characteristics of such sources capable to emit metal projectiles ranging from atomic ions with different charge states to polyatomic ions and to large metal clusters having sizes up to a few nanometers. They highlight their interest and relevance to current nanoscience challenges in terms of ultimate patterning or bottom-up nanofabrication capabilities.

Advanced Ion Source Technology for High Resolution and Stable FIB Nanofabrication employing Gallium and new Ion Species

FIB systems and combined FIB-SEM microscopes are widely used for sample preparation and various analytical tasks. Instrumentation has seen different developments in recent years in the area of source technology and also in the intended breadth of application space. The Gallium-based LMIS (liquid metal ion source), which has been ubiquitous with -FIBfor many decades, is partly giving way to GFIS (gas field ion source) microscopes, as well as Xenon -plasmasources. This trend has been mainly driven by ultra-high resolution microscopy and large volume milling for special sample preparation applications, respectively.