New nanostructured materials break the old limits of optical lenses
Source: “Far-Field Optical Hyperlens Magnifying Sub-Diffraction-Limited Objects”
Xiang Zhang et al.
Science 315: 1686
Results: Researchers at the University of California, Berkeley, have developed a lens that can resolve details too small for conventional optical microscopes. Using it, they could distinguish two parallel lines 130 nanometers apart; seen through a conventional microscope, the lines looked like a single, thick line.
Why it matters: Light-based devices such as optical microscopes have long been limited to resolving or producing features half the wavelength of the light being used. Thus visible light cannot resolve anything smaller than about 200 nanometers. The new lens could make it possible to observe cellular processes never before seen. It could also be used to project images with extremely fine features, increasing the precision of photolithography or enabling much more data to be crammed onto a DVD.
Methods: The researchers carved a valley shaped like a half-cylinder into a piece of quartz. They then deposited alternating layers of silver and aluminum oxide on the walls of the cylinder. Each layer was just 35 nanometers thick and took the curved shape of the quartz. This arrangement enables the lens to gather more visual information about the object being viewed, which it then passes on to an otherwise conventional microscope.
Next Steps: So far, the lens can be used to view only things in contact with the bottom of its U-shaped valley. It should be possible to build a version of it that does not need to touch the object being viewed.
Batteries that make themselves could serve as tiny power sources in micromachines or microelectronics
Source: “Self-Assembling Colloidal-Scale Devices: Selecting and Using Short-Range Surface Forces between Conductive Solids”
Yet-Ming Chiang et al.
Advanced Functional Materials 17(3): 379-389
Results: Thanks to a better understanding of short-range forces between microscopic particles, MIT researchers were able to identify materials that, combined in a solution, will arrange themselves to form a working rechargeable battery. In a prototype, attractive forces cause microscopic carbon particles to aggregate, forming an electrode and attaching to a current collector. Another, preëxisting electrode–a solid slab–repulses the particles, creating the necessary gap between electrodes.
Why it matters: Such materials could self-assemble into form-fitting batteries in electronic devices. The materials could also be used in tiny sensors or micromachines.
Methods: The researchers combined theoretical analysis with precise measurements of the short-range attractive and repulsive forces between particles of different materials. The measurements were made by attaching particles to the tip of an atomic force microscope. The interplay of forces caused the researchers’ chosen materials to sort themselves into a working battery.
Next Steps: To make the battery more rugged, the researchers want to replace the liquid electrolyte used in the prototype with a polymer. Also, future prototypes could use self-assembling particles for both electrodes, not just one.
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