Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Heat and light get larger at the nanoscale

01.04.2016

Columbia-led research team first to demonstrate a strong, non-contact heat transfer channel using light with performances that could lead to high efficiency electricity generation

In a new study recently published in Nature Nanotechnology, researchers from Columbia Engineering, Cornell, and Stanford have demonstrated heat transfer can be made 100 times stronger than has been predicted, simply by bringing two objects extremely close--at nanoscale distances--without touching. Led by Columbia Engineering's Michal Lipson and Stanford Engineering's Shanhui Fan, the team used custom-made ultra-high precision micro-mechanical displacement controllers to achieve heat transfer using light at the largest magnitude reported to date between two parallel objects.


This is a schematic of two beams at different temperatures exchanging heat using light. In the situation when the beams are far from each other (left), heat transfer resulting from thermal radiation is small. When the beams are brought very close from each other (right) heat transfer becomes almost 100 times larger than predicted by conventional thermal radiation laws.

Credit: Raphael St-Gelais, Lipson Nanophotonics Group, Columbia Engineering

"At separations as small as 40 nanometers, we achieved almost a 100-fold enhancement of heat transfer compared to classical predictions," says Lipson, Eugene Higgins Professor of Electrical Engineering and professor of applied physics. "This is very exciting as it means that light could now become a dominant heat transfer channel between objects that usually exchange heat mostly through conduction or convection. And, while other teams have demonstrated heat transfer using light at the nanoscale before, we are the first to reach performances that could be used for energy applications, such as directly converting heat to electricity using photovoltaic cells."

All objects in our environment exchange heat with their surroundings using light. This includes the light coming at us from the sun, the glowing red color of the heating element inside our toaster ovens, or the "night vision" cameras that enable image recording even in complete darkness. But heat exchange using light is usually very weak compared to what can be achieved by conduction (i.e., by simply putting two objects in contact with each other) or by convection (i.e., using hot air). Radiative heat transfer at nanoscale distances, while theorized, has been especially challenging to achieve because of the difficulty of maintaining large thermal gradients over nanometer-scale distances while avoiding other heat transfer mechanisms like conduction.

Lipson's team was able to bring objects at different temperatures very close to each other--at distances smaller than 100 nanometers, or 1/1000th of the diameter of a strand of human hair. They were able to demonstrate near-field radiative heat transfer between parallel SiC (silicon carbide) nanobeams in the deep sub-wavelength regime. They used a high-precision micro-electromechanical system (MEMS) to control the distance between the beams and exploited the mechanical stability of nanobeams under high tensile stress to minimize thermal buckling effects, thus keeping control of the nanometer-scale separation even at large thermal gradients.

Using this approach, the team was able to bring two parallel objects at different temperatures to distances as small as 42 nm without touching. In this case they observed that the heat transfer between the objects was close to 100 times stronger that what is predicted by conventional thermal radiation laws (i.e. "blackbody radiation"). They were able to repeat this experiment for temperature differences as high as 260oC (500oF) between the two objects. Such high temperature difference is especially important for energy conversion applications since, in these cases, the conversion efficiency is always proportional to the thermal difference between the hot and the cold objects involved.

"An important implication of our work is that thermal radiation can now be used as a dominant heat transfer mechanism between objects at different temperatures," explains Raphael St-Gelais, the study's lead author and postdoctoral fellow working with Lipson at Columbia Engineering. "This means that we can control heat flow with a lot of the same techniques we have for manipulating light. This is a big deal since there are a lot of interesting things we can do with light, such as converting it to electricity using photovoltaic cells."

St-Gelais and Linxiao Zhu, who co-authored the study and is a PhD candidate in Fan's group at Stanford, note that the team's approach can be scaled up to a larger effective area by simply arraying several nanobeams--on top of a photovoltaic cell, for example--and by individually controlling their out-of-plane displacement using MEMS actuators. The researchers are now looking at applying their same approach for ultra-high-precision displacement control, this time with an actual photovoltaic cell to generate electricity directly from heat.

"This very strong, non-contact, heat transfer channel could be used for controlling the temperature of delicate nano devices that cannot be touched, or for very efficiently converting heat to electricity by radiating large amounts of heat from a hot object to a photovoltaic cell in its extreme proximity," Lipson adds. "And if we can shine a large amount of heat in the form of light from a hot object to a photovoltaic cell, we could potentially create compact modules for direct conversion of heat to electrical power. These modules could be used inside cars, for instance, to convert wasted heat from the combustion engine back to useful electrical power. We could also use them in our homes to generate electricity from alternative energy sources such as biofuels and stored solar energy."

###

The work received funding from the Defense Advanced Research Projects Agency for award FA8650-14-1-7406 as well as additional support from the Fonds de recherche du Québec?Nature et Technologies (FRQNT) and from the Natural Sciences and Engineering Research Council of Canada (NSERC).

LINKS

Study -- dx.doi.org/10.1038/nnano.2016.20

http://www.engineering.columbia.edu/

http://apam.columbia.edu/michal-lipson-0

http://lipson.ee.columbia.edu/

http://web.stanford.edu/group/fan/

Holly Evarts | EurekAlert!

More articles from Power and Electrical Engineering:

nachricht Laser sensor LAH-G1 - optical distance sensors with measurement value display
15.08.2017 | WayCon Positionsmesstechnik GmbH

nachricht Engineers find better way to detect nanoparticles
14.08.2017 | Washington University in St. Louis

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>