Imad Ibrahim

NaMLab GmbH · SiNW group

Many biomarkers including neurotransmitters are found in external body fluids, such as sweat or saliva, but at lower titration levels than they are present in blood. Efficient detection of such biomarkers thus requires, on the one hand, to use techniques offering high sensitivity, and, on the other hand, to use a miniaturized format to carry out di...

The unique electrostatic properties of semiconductor nanowires enable the realization of novel transistor types by the possibility to use surround gate architectures resembling ideal gate electrostatic control. Nevertheless one fundamental issue of semiconducting nanowire channels is the reliable control of doping to adjust the charge carrier conce...

We developed chemiresistor-type biosensors based on carbon nanotubes for highly efficient and fast detection of avian influenza virus (AIV) subtype H5N1 DNA sequences. Semiconducting single-walled carbon nanotube (sc-SWCNTs) or nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) were used as two alternative active sensing elements, and their se...

The exciting electrical properties of single wall carbon nanotubes continue to promise as a future class of electronic materials, yet the manufacturing challenges remain significant. The key chal-lenges are to determine fabrication approaches for complex and flexible arrangements of nano-tube devices that are reliable, rapid and reproducible. Reali...

Carbon nanotubes (CNTs) show great potential for biosensing, because of their quasi-one-dimensional structure offering high sensitivity, high electron mobility and their effective and facile integration into electrode network. In this study, we fabricated two types of chemiresistor arrays: based on nitrogen doped multi-walled CNTs (N-MWCNTs) and se...

The discovery of graphene and carbon nanotubes (rolled-up graphene) has excited the world because their extraordinary properties promise tremendous developments in many areas. Like any materials with application potential, it needs to be fabricated in an economically viable manner and at the same time provides the necessary quality for relevant app...

The search for ways to synthesize single wall carbon nanotubes (SWCNT) of a given electronic type in a controlled manner persists despite great challenges because the potential rewards are huge, in particular as a material beyond silicon. In this work we take a systematic look at three primary aspects of semiconducting enriched SWCNT grown by chemi...

Amorphous carbon thin films are technologically important materials that range in use from the semiconductor industry to corrosion-resistant films. Their conversion to crystalline graphene layers has long been pursued; however, typically this requires excessively high temperatures. Thus, crystallization routes which require reduced temperatures are...

The role of sample chamber configuration for the chemical vapor deposition of graphene over copper was investigated in detail. A configuration in which the gas flow is unrestricted was shown to lead to graphene with an inhomogeneous number of layers (between 1 and 3). An alternative configuration in which one end of the inner tube (in which the sam...

As a consequence of graphene oxides (GOs) high chemical versatility, there is great interest in functionalized as a nanocarrier for in vitro and in vivo drug delivery. Within this review, the structure and properties of GO that allow covalent and non-covalent functionalization are discussed. In short, toxicity investigations show functionalized GO...

Single-walled carbon nanotubes are shown to have self-repairing capabilities exceeding that predicted by theory. Time-series aberration-corrected low-voltage transmission electron microscopy is used to study the defect dynamics of single-walled carbon nanotubes in situ. We confirm experimentally previous theoretical predictions for the agglomeratio...

The exceedingly high current capacity of single wall carbon nanotubes (SWCNTs) and the high currents that SWCNT thin films can sustain are driving significant efforts to fabricate high quality horizontally aligned SWCNTs. Dielectrophoresis is being increasingly used to prepare aligned nanotubes. However, the aligned nanotubes are generally of low q...

All-carbon single-walled carbon nanotubes (SWCNTs) were successfully synthesized, nucleated using a fullerene derivative. A systematic investigation into the initial preparation of C60 fullerenes as growth nucleators for the SWCNTs was conducted. Enhancement in the yield of the produced SWCNT has been achieved with exploring different dispersing me...

Systematic studies to investigate binary catalysts combining the well-established standard transition metals Fe, Co and Ni with less used metals such as Al, Pb, Dy, Gd, Ga and Zn were explored in supported catalyst chemical vapor deposition. The findings show different carbon nanostructures can be obtained depending on the choice of catalyst mix. C...

Our understanding of the catalyst-free growth of single walled carbon nanotubes (SWNT) by chemical vapour deposition is limited. Toward improving our knowledge-base we conducted systematic investigations into the initial preparation of C60 fullerenes as nucleation precursors for single wall, and even double wall carbon nanotube fabrication. The rol...

Amorphous carbon irradiated by electrons at acceleration voltages of 80 kV is studied in high-resolution transmission electron microscopy. Amorphous carbon deposited on graphene or h-BN membranes forms graphene layers parallel to the support due to van der Waals interactions. One can use deposited amorphous carbon to engineer graphene either for it...

Single-walled carbon nanotubes (SWCNTs) have attractive electrical and physical properties, which make them very promising for use in various applications. For some applications however, in particular those involving electronics, SWCNTs need to be synthesized with a high degree of control with respect to yield, length, alignment, diameter, and chir...

Here, we report the growth of homogenously horizontally aligned single wall carbon nanotubes on stable temperature cut single crystal quartz using chemical vapor deposition with controllable yield and length from binary metallic mixtures as well as fullerene derivatives. We manage the yield and length of the as-grown tubes on stable temperature cut...

Graphene has a multitude of striking properties that make it an exceedingly attractive material for various applications, many of which will emerge over the next decade. However, one of the most promising applications lie in exploiting its peculiar electronic properties which are governed by its electrons obeying a linear dispersion relation. This...

The initial development of carbon nanotube synthesis revolved heavily around the use of 3d valence transition metals such as Fe, Ni, and Co. More recently, noble metals (e.g. Au) and poor metals (e.g. In, Pb) have been shown to also yield carbon nanotubes. In addition, various ceramics and semiconductors can serve as catalytic particles suitable fo...

The formation of carbon nanostructures using silica nanoparticles from quartz substrates as a catalyst in an aerosol assisted chemical vapor deposition process was examined. The silica particles are reduced to silicon carbide via a carbothermal reduction process. The recyclability of the explored quartz substrates is also presented. The addition of...

The potential of MgO and ZrO2 as catalytically active substrates for graphene formation via thermal CVD is explored. Experimental observations show the growth of single and multi-layer graphene nano-flakes over MgO and ZrO2 at low temperatures. The graphene nano-flakes are found to anchor at step sites. Ab initio calculations indicate step sites ar...

In this study, DNA block copolymer (DBC) micelles with a polystyrene (PS) core and a single‐stranded (ss) DNA shell were doped with ferrocene (Fc) molecules. Tapping mode atomic force microscopy (AFM) was used to study the morphology of the doped and undoped block copolymer aggregates. We show that introducing Fc molecules into the hydrophobic core...

Intramolecular carbon nanotube (CNT) junctions are nanotubes with kinks generated by heptagon-pentagon defect pairs. They are very attractive functional building blocks for future electronics, as they can be used as diodes and transistors. Usually CNT junctions are synthesized incidentally [1]. Using chemical vapor deposition techniques we are tryi...

The use of mixed catalysts for the high-yield production of single-walled carbon nanotubes is well-known. The mechanisms behind the improved yield are poorly understood. In this study, we systematically explore different catalyst combinations from Ni, Co, and Mo for the synthesis of carbon nanotubes via laser evaporation. Our findings reveal that t...

Silica fumed nanoparticles were dispersed in polyacrylamide thin films by direct mixing. Atomic Force Microscopy study was carried out in order to analyze the surface roughness. Height distribution of surface roughness changes from Gaussian like for polyacrylamide to skew asymmetric when increasing the silica concentration. The length of the distri...

High sensitive non-contact tapping mode atomic force microscopy has been used to study the effect of Cu+2 doping on the nano-scale surface roughness of polyacrylamide replicas. The study was carried out by determining the root mean square roughness of the polymer surface as a function of doping concentration on glass substrates. Results show that d...