It is quite difficult - not least because there is no consensus about a proper definition - to assess the scope of nanotechnology research and its impact on the overall scientific body as well as its commercialization prospects. In a new attempt to put some numbers behind the general perception of a rapidly expanding nanotechnology field, two researchers at UC Davis have trawled scientific databases and come up with some surprising findings. For instance, that China has now overtaken the USA in annual research paper output related to nanoscience and nanotechnology. Also, the proportion of "nano"-related articles relative to the total size of the subject categories (such as physics, materials sciences or chemistry) has risen dramatically over the past 13 years.
Electronic devices with muscles-like stretchability have long been pursued, but not achieved due to the requirement that all materials in the devices - electrodes, semiconductor, and dielectric - are stretchable. In their pursuit of fully flexible and stretchable electronic devices, researchers have already reported stretchable solar cells and transistors as well as stretchable active-matrix displays. The nanomaterials used for these purposes range from coiled nanowires to graphene. Recently, researchers at UCLA have successfully demonstrated a stretchable polymer composite that is highly transparent and highly conductive, and applied this nanocomposite material to fabricating stretchable devices. This work represents a proof-of-concept, highly stretchable semiconductor device wherein every part of the device is intrinsically stretchable.
Molecular separations are extremely important in a wide range of technologies, from conventional proteomics to pathogen detection and DNA fingerprinting. A complication arises from the fact that molecular components in mixtures can span an enormous range of concentration. Conventional approaches such as antibody depletion are not sensitive enough to detect numerous medically significant biomarkers, whose incidence in blood could be as much as a trillion times less abundant than the most plentiful protein, albumin. New research shows a new path in miniaturized molecular separations. It describes a new device that demonstrates simultaneous concentration and separation of proteins by conductivity gradient focusing. Concentration and separation take place in an electric-field-driven 120 nm deep nanochannel that supports a stable salt and conductivity gradient. The results show that relevant proteins can be concentrated to detectable levels.
The atomic structures of nanoscale contacts are not available in most experiments on quantum transport. Scanning tunneling microscopy operates at a tip-sample distance of a few angstroms and relies on probing a conductive surface in the evanescent tail of electronic states. By decreasing the tip-sample distance the sensitivity to chemical interactions can be enhanced. This has already been demonstrated in non-contact atomic force microscopy, where the oscillating tip comes for short periods of time within the range of chemical interactions. A team of scientists has now developed Quantum Point Contact Microscopy as a novel imaging mode of low-temperature STM, where instead of measuring a current through a tunneling junction, a transport current through a quantum point contact formed by a single atom between the STM tip and the surface is recorded.
Extracellular signaling molecules are the language that cells use to communicate with each other. These molecules transfer information not only via their chemical compositions but also through the way they are distributed in space and time throughout the cellular environment. With the development of nanosensing techniques, scientists are trying to to eavesdrop on the cellular whisper and they getting closer to deciphering extracellular signaling - an important task in understanding how cells organize themselves, for instance during organ development or immune responses. Now, researchers have reported a novel sensing technique to interrogate extracellular signaling at the subcellular level. They developed a nanoplasmonic resonator array to enhance fluorescent immunoassay signals up to more than one hundred times to enable the first time submicrometer resolution quantitative mapping of endogenous cytokine secretion from an individual cell in nanoscale close to the cell.
DNA origami is a design technique that is used by nanotechnology researchers to fold DNA strands into something resembling a programmable pegboard on which different nanocomponents can be attached. These DNA assemblies allow the bottom-up fabrication of complex nanostructures with arbitrary shapes and patterns on a 100 nm scale. For instance, DNA origami have been heralded as a potential breakthrough for the creation of nanoscale circuits and devices. DNA can also be metallized with different metals, resulting in conducting nanowires. Researchers have now have developed a method to assemble metallic nanocircuits with arbitrary shapes, by attaching metallic nanoparticles to select locations of the DNA origami and then fusing them to form wires, rings, or any other complex shape. These pre-designed structures are programmed by fully utilizing the self-assembling and recognition properties of DNA.
Researchers in Finland and Israel have explored the feasibility of using superhydrophobicity for guided transport of water droplets in microfluidic devices. They demonstrate a new, simple and general approach for transportation of water droplets based on superhydrophobic technology. Water droplets are transported at high velocity in almost totally water-repellent tracks with vertical walls. Drops move in open tracks, machined in metal or silicon wafers, using gravity or using electrostatic charge. Usually, in digital microfluidics, droplets are formed in a system of two immiscible liquids, for example, water in oil, and the liquid volume is transported in microchannels using pumps and valves. In this new approach droplets in air can be used. Employing superhydrophobic tracks, droplets can be transported with low friction and high efficiency.
Super-tough materials with exceptional mechanical properties are in critical need for applications under extreme conditions such as jet engines, power turbines, catalytic heat exchangers, military armors, airplanes, and spacecraft. Researchers involved in improving man-made composite materials are trying to understand how some of the amazing high-performance materials found in nature can be copied or even improved upon. Nature has evolved complex bottom-up methods for fabricating ordered nanostructured materials that often have extraordinary mechanical strength and toughness. The main problem in making nanocomposite materials is how the separate components can be interfaced without losing the good properties of each component. Researchers were now able to show that biomolecules that may seem soft and fragile can actually strengthen a composite material by creating cohesion between two materials that differ much from each other.