Researchers have demonstrated that perfect orbital angular momentum could be generated in optical nanostructures inspired by catenaries - the curve that a free-hanging chain assumes under its own weight. They used optical catenary-shaped structures to convert circularly polarized light to helically-phased beam carrying orbital angular momentum. Similar to the 'catenary of equal strength', the phase gradient of the optical catenary is equal everywhere, which is a direct result of its special geometric shape.
Synthesis of holey two-dimensional (2D) nanosheets with defined hole morphology and hole edge structures remains a great challenge for graphene. It is also an issue for other 2D nanomaterials, such as hexagonal boron nitride (h-BN) and molybdenum disulfide. In new work, researchers have reported a facile, controllable, and scalable method to carve geometrically defined pit/hole shapes and edges on h-BN basal plane surfaces via oxidative etching in air using silver nanoparticles as catalysts.
The development of nanoscale devices and applications requires ultra-sensitive sensing systems that can offer not only atomic resolution imaging but also sub nanometer scale displacement detection, zeptogram level mass sensing, or single bio-molecular sensing. Researchers have now developed a novel sensor that addresses some of the shortcomings that have plagued existing optical scanning systems , namely size, complexity, and cost. This sensing technology is completely electrical and capable of sensing very small displacement as low as in the femtometer range.
To overcome the pixel size limitation of existing digital image sensors, both new materials with enormous photoelectric properties and novel device architectures are required. In new work, researchers are now reporting ultra-high resolution nanorod digital image sensor (NDIS) which is fabricated by sandwiching vertically aligned zinc oxide nanorod arrays between orthogonal top and bottom nanostripe electrodes. The most important application of the NDIS is as a next-generation digital image sensor with ultra-high resolution, well beyond the limit of existing techniques.
Researchers developed a simple controllable set-up for drawing single filament nanofibers from polymer solutions or melts using a rotating rod or a set of rods (round brush). This method can be used to produce 3D tissue scaffolds by winding nanofibers onto spools of different shapes and dimensions and depositing cells of interest at the same time. The new method, which the scientists named touch-spinning, has excellent control over the fiber diameter and is compatible with all kinds of polymeric materials, polymer melts and solutions, polymer composite materials, and biopolymers.
Researchers engineered synthetic nanomotors that self-propel and autonomously detect surface cracks in electronic devices and rapidly restore the conductive pathway. These nanomotors were inspired by the chemotaxis of neutrophils toward inflammation sites and the aggregation of platelets at the collagen fibers of a wound to stop bleeding. The catalytic nanomotors are composed of conductive gold/platinum spherical Janus particles that self-propel efficiently in the presence of hydrogen peroxide fuel.
With increasing sensitivity, electrical, mechanical and optical sensors are able to detect low molecular weight chemical and biological analytes under ever more dilute conditions. At the same time, though, researchers want to keep the sensing process as simple as possible without complex functionalization and complicated preparation steps for the in situ detection. A novel graphene-gold metasurface-based biosensing architectures makes extreme phase singularities possible due to a strong field enhancement on the graphene-gold interface.
A typical preliminary test for tuberculosis includes culturing the samples for at least 1-2 weeks in a lab, followed by examination under a fluorescence microscope. The lack of rapid, accurate, and inexpensive point-of-care tools for detecting low amounts of M. Tuberculosis is a critical bottleneck in early diagnosis and appropriate treatment. Researchers have now developed a rapid and flexible nano-biosensor for diagnosing TB in early stages using smart phones.