Stories tagged plasmonics


Quest for the best optical display

Better resolution displays
Better resolution displaysCourtesy Yutaka Tsutano

I have been waiting for the new iPod Touch. I want a display screen so sharp, it looks like a photograph. The "retina display" creates an image out of pixels that are only 78 nanometers. How small is that? Well, more than 300 of these pixels are packed in each inch. Supposedly this is the limit for human perception, or as some fanboys might say, "It doesn't get any better than this!"

Plasmonic nanoresonators

University of Michigan researchers can do better, though, Their paper in Nature Communications titled, Plasmonic nanoresonators for high-resolution colour filtering and spectral imaging explains how pixels of only 10 microns can be produced.

Such pixel densities could make the technology useful in projection displays, as well as wearable, bendable or extremely compact displays, according to the researchers.

How does it work?

The resonators are kind of like a light filter. Two nano thin layers of metal selectively allow light to pass through small sets of slits. The slit spacing determines which wavelength of light makes it through the slits.

Red light emanates from slits set around 360 nanometers apart; green from those about 270 nanometers apart, and blue from those approximately 225 nanometers apart. The differently spaced gratings essentially catch different wavelengths of light and resonantly transmit through the stacks.

These displays are simpler, use fewer parts, are more efficient, and should be cheaper to make. I am not going to wait, though.


Nano structure self assembly
Nano structure self assemblyCourtesy Scott Warren and Uli Wiesner, Cornell University

Materials scientists perfect nano assembly of catalytic meshes

Catalysts, because of its shape, can speed up chemical reactions. Platinum is a useful catalyst in fuel cells but because it costs over $2000 an ounce, it needs to be used efficiently. One way to maximize the effectiveness of platinum is to maximize its surface area.

Cornell researchers have developed a method to self-assemble metals into complex configurations with structural details about 100 times smaller than a bacterial cell by guiding metal particles into the desired form using soft polymers. NSF News

How to self-assemble porous nano mesh

To keep nano spheres of platinum from clumping or "globbing" they are coated with an organic material known as a ligand. The innovative use of the ligands allows for the metal nanoparticles to be dissolved in a solution containing long co-polymer chains, or blocks, of molecules linked together to form a predictable pattern. After the spheres have filled in the spaces created by the co-polymer chains, heat is applied until the polymer turns to a carbon scaffold. The scaffold holds the platinum spheres in place until cooled. The carbon is then dissolved away leaving an intricate hexagonal mesh of platinum (see image above).

New surface textures will benefit plasmonics science

These metalic surfaces will also be of interest to scientists working in an area called plasmonics. Plasmonics is the study of interactions among metal surfaces, light, and density waves of electrons, known as plasmons. Improved optics applications, like lasers, displays, and lenses and better transmission of information within microchips will be some benefits.