Showing Spotlights 1137 - 1144 of 2140 in category (newest first):
Projection photolithography is mostly limited to flat surfaces. However, many emerging areas of micro- and nanotechnology applications, be it in optics, imaging, sensors or bioengineering, increasingly require the fabrication of microscopic and nanoscopic patterns on nonplanar surfaces. Contact printing and imprinting methods can cope with certain curved surfaces but appear to be restricted to those having a constant magnitude of curvature and a large radius of curvature relative to the arc length at least in one dimension. Researchers have now demonstrated that hexagonal noncontiguously packed (HNCP) colloidal crystals trapped at the air-water interface can be directly transferred onto solid substrates to give HNCP and distorted HNCP patterns. This bottom-up method uses self-assembled nanoparticle arrays and is not limited to flat surfaces at all.
Dec 6th, 2010
Dip-Pen Nanolithography (DPN) is a scanning probe lithography technique in which the tip of an atomic force microscope (AFM) is used to deliver molecules to a surface, allowing nanostructured surface patterning on scales of under 100 nm. This direct-write technique offers high-resolution patterning capabilities for a number of molecular and biomolecular 'inks' on a variety of substrates, such as metals, semiconductors, and monolayer functionalized surfaces. It's becoming a work-horse tool for the scientist interested in fabricating and studying soft- and hard-matter on the sub-100nm length scale.
Using DPN for fabricating graphene devices has not been previously shown. Researchers at Stanford University have now evaluated DPN as an alternative to conventional electron-beam lithography (EBL) for tailoring such devices.
Dec 3rd, 2010
For the visionary goals of nanotechnology, functional and perhaps autonomous molecular motors will play an essential part, just like electric motors can be found in many appliances today. These nanomachines could perform functions similar to the biological molecular motors found in living cells, things like transporting and assembling molecules, or facilitating chemical reactions by pumping protons through membranes. Although applications of molecular motors are still in the future, the results of early-day studies are already spectacular: well-designed molecules or supramolecules show different kinds of motion - fueled by different driving forces such as light, heat, or chemical reactions - resulting in molecular shuttles, molecular elevators and rotating motors. A team of researchers is now proposing a conceptually new design of molecular motor based on electric field actuation and electric current detection of the rotational motion of a molecular dipole embedded in a three-terminal single-molecule device.
Dec 2nd, 2010
Global warming, caused by a build-up of greenhouse gases, in particular carbon dioxide, in the atmosphere, has led to numerous proposals on how to capture and store CO2 in order to mitigate the damaging emissions from fossil fuels. Today we take a look at carbon sequestration and subsequent storage in geological formations (geosequestration) - a proposal that is already being tested on a large scale. The idea behind coal-bed geosequestration is that you inject a huge amount of carbon dioxide into deep unmined coal seams. Due to strong adsorption forces, the carbon dioxide will be adsorbed in coal. It will not be desorbed and gradually transform to solid rocks. Moreover the technology is already developed and in use for oil and gas mining. However, the fundamental problem is so-called adsorption-induced deformation of coal or any other porous material.
Nov 30th, 2010
One of the many fascinating concepts in nanotechnology is the vision of molecular electronics where researchers are investigating nanostructured materials to build electronics from individual molecules. If realized, the shift in size from even the most densely packed computer chip today would be staggering. Molecular electronics aims at the fundamental understanding of charge transport through molecules and is motivated by the vision of molecular circuits to enable miniscule, powerful and energy efficient computers. A research team in Germany has now demonstrated that rigidly wired molecules can emit light under voltage bias. This result is important for fundamental science but it also adds to the molecular electronics vision an optoelectronic component, i.e. the development of optoelectronic components on the basis of single molecules.
Nov 29th, 2010
Scientists have shown that two pH response moieties - a pH solubility switch and a pH labile group - can be incorporated into the backbone of polymers which can then be formulated into dual responsive nanoparticles encapsulating small hydrophobic molecules and larger protein payloads. As nanoparticles they function akin to an AND logic gate. The beta-aminoester backbone moiety provides a pH triggered solubility switch, only when this switch is 'ON' does the ketal moiety also turn 'ON' to undergo rapid acid catalyzed hydrolysis. This system seems to be a promising vehicle for the administration of hydrophilic and hydrophobic payloads into target areas of the human body.
Nov 24th, 2010
Since 2009, NT-MDT Co. has been holding a contest of scientific art images obtained by atomic force microscopes (AFM). Each month, researchers from around the world submit their AFM scans to the dedicated ProIMAGE contest site where they are then subject to online voting by site visitors. According to NT-MDT, a simple gender analysis of monthly winners shows that a) the percentage of women has been rising for two years, and b) women attract more votes originating from social networks. Of course, these observations are more trivia than hard scientific facts. Nevertheless, they appear to reveal a phenomenon of higher online communication skills among female scientists. It remains to be seen to what degree social networks a la Facebook and LinkedIn will change the way the scientific community interacts and communicates.
Nov 23rd, 2010
The workhorse of current nanofabrication processes, electron beam lithography (EBL), has good resolution but has good resolution, it is difficult to precisely control the pattern size at the sub-20 nm scale due to the proximity effect and the large beam spot. A more recent nanolithographic strategy, the molecular ruler (MR) method, shows great promise it can precisely control the size of the gap at the nanoscale. Although EBL and MR have been combined before in attempting high-resolution nanofabrication in the sub-20nm regime, the results were always less than optimal because the electron beam irradiation damage to the MR influenced the formation of nanogaps. Researchers in Japan have now developed a post-EBL process, which does not damage MR molecular layers, and fabricated nanogap structures at the expected positions with high product yield.
Nov 22nd, 2010