There is no need of rain...Nanostructures can taste the Rainbow anyway!

What is nanostructures and basics informations about nanotechnology

Nanotechnology ("nanotech") is manipulation of matter on an atomic, molecular, and supramolecular scale. A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defines nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers. 

Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in nanomedicine, nanoelectronics, biomaterials energy production, and consumer products. On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nanomaterials, and their potential effects on global economics, as well as speculation about various doomsday scenarios. 

In describing nanostructures, it is necessary to differentiate between the number of dimensions in the volume of an object which are on the nanoscale. Nanotextured surfaces have one dimension on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have two dimensions on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100 nm; its length can be far more. Finally, spherical nanoparticles have three dimensions on the nanoscale, i.e., the particle is between 0.1 and 100 nm in each spatial dimension.

The term nanostructure is often used when referring to magnetic technology.

What is thermoelectrics?

Thermoelectric materials show the thermoelectric effect in a strong or convenient form.
The thermoelectric effect refers to phenomena by which either a temperature difference creates an electric potential or an electric potential creates a temperature difference. These phenomena are known more specifically as the Seebeck effect (converting temperature to current), Peltier effect (converting current to temperature), and Thomson effect (conductor heating/cooling). While all materials have a nonzero thermoelectric effect, in most materials it is too small to be useful. However, low-cost materials that have a sufficiently strong thermoelectric effect (and other required properties) could be used in applications including power generation and refrigeration.

What is new?

Engineers at Caltech have for the first time developed a light detector that combines two disparate technologies—nanophotonics, which manipulates light at the nanoscale, and thermoelectrics, which translates temperature differences directly into electron voltage—to distinguish different wavelengths (colors) of light, including both visible and infrared wavelengths, at high resolution.

Artist's representation of a conceptual design for the color detector

How it works?

The new detector, described in a paper in Nature Nanotechnology on May 22, operates about 10 to 100 times faster than current comparable thermoelectric devices and is capable of detecting light across a wider range of the electromagnetic spectrum than traditional light detectors. In traditional light detectors, incoming photons of light are absorbed in a semiconductor and excite electrons that are captured by the detector. The movement of these light-excited electrons produces an electric current—a signal—that can be measured and quantified. While effective, this type of system makes it difficult to "see" infrared light, which is made up of lower-energy photons than those in visible light.

How they succeed it?
The researchers created nanostructures with a variety of widths, that absorb different wavelengths—colors—of light. When these nanostructures absorb light, they generate an electric current with a strength that corresponds to the light wavelength that is absorbed.
The detectors were fabricated in the Kavli Nanoscience Institute cleanroom at Caltech, where the team created subwavelength structures using a combination of vapor deposition (which condenses atom-thin layers of material on a surface from an element-rich mist) and electron beam lithography (which then cuts nanoscale patterns in that material using a focused beam of electrons). The structures, which resonate and generate a signal when they absorb photons with specific wavelengths, were created from alloys with well-known thermoelectric properties, but the research is applicable to a wide range of materials, the authors say.

Applications of light detectorsLight detectors that distinguish between different colors of light or heat are used in a variety of applications, including satellites that study changing vegetation and landscape on the earth and medical imagers that distinguish between healthy and cancerous cells based on their color variations.

Advantage

Because the new detectors are potentially capable of capturing infrared wavelengths of sunlight and heat that cannot be collected efficiently by conventional solar materials, the technology could lead to better solar cells and imaging devices.

References: wikipedia.com  ~  phys.org/news  ~