Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

One-way street planned for heat

05.03.2002


Physicists design material that conducts one way and insulates the other.


Stiffness and springiness could make heat stop and go.
© GettyImages



European physicists have sketched out a blueprint for a valve that lets heat pass only one way. The proposed material conducts heat flowing in one direction, but also behaves as an insulator, stopping it going the other way1.

In theory, a heat valve could keep parts of microelectronic circuitry cool or channel heat to chip-sized chemical reactors, which are currently being developed for high-efficiency chemical synthesis or ultra-sensitive analysis.


Marcello Terraneo of Insubria University in Como, Italy, and colleagues suggest that the valve material would be a one-dimensional solid: a chain of linked particles such as atoms. The chain would be designed to shake in different ways, depending on which end it is vibrated from.

Strung together in the right way, some biological molecules, such as DNA strands, might have the required properties, the researchers speculate. Living cells may even control the flow of heat energy this way already.

Good vibrations

Heat corresponds to the movement of atoms. When atoms are joined together in molecules, they vibrate back and forth. The larger the vibrations, the hotter the material.

Heat is conducted along a chain of particles because vibrations travel from one particle to the next. If one end is attached to a hot material and the other to something cooler, the hot end jiggles more. This jiggling goes down the chain to the cool end.

A chain of particles of identical weights linked by ideal, so-called ’harmonic’ springs vibrates at the same frequency irrespective of the amplitude of the vibrations. In real chains, like DNA, the links are not ideal, but anharmonic: their vibration frequency depends on amplitude.

One-way heat transfer would make use of anharmonicity. A chain divided into three sections, say Terraneo’s team, can insulate heat if the middle section acts like a strongly anharmonic spring while the outer two are softer and more harmonic.

If one of the end sections is stiffer than the other, more heat can flow in one direction than the other. The anharmonic middle of the chain can jiggle in sympathy with the stiff end when it is cold and the soft end when it is hot - but not vice versa. So the chain transmits heat from a hot, soft end to a cool stiff end. If the stiff end gets hot and the soft cold, the middle section blocks vibrations, so the chain as a whole acts as an insulator.

References

  1. Terraneo, M., Peyrard,, M. & Casati, G. Controlling the energy flow in nonlinear lattices: a model for a thermal rectifier. Physical Review Letters, 88, 094302, (2002).


PHILIP BALL | © Nature News Service

More articles from Physics and Astronomy:

nachricht Midwife and signpost for photons
11.12.2017 | Julius-Maximilians-Universität Würzburg

nachricht New research identifies how 3-D printed metals can be both strong and ductile
11.12.2017 | University of Birmingham

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

Im Focus: Virtual Reality for Bacteria

An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications

Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...

Im Focus: A space-time sensor for light-matter interactions

Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.

The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Midwife and signpost for photons

11.12.2017 | Physics and Astronomy

How do megacities impact coastal seas? Searching for evidence in Chinese marginal seas

11.12.2017 | Earth Sciences

PhoxTroT: Optical Interconnect Technologies Revolutionized Data Centers and HPC Systems

11.12.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>