Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Heat and light get larger at the nanoscale


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).


Study --

Holly Evarts | EurekAlert!

More articles from Power and Electrical Engineering:

nachricht 'Super yeast' has the power to improve economics of biofuels
18.10.2016 | University of Wisconsin-Madison

nachricht Engineers reveal fabrication process for revolutionary transparent sensors
14.10.2016 | University of Wisconsin-Madison

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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>