One-way street planned for heat

Stiffness and springiness could make heat stop and go. <br>© GettyImages <br>

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

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.


  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).

Media Contact

PHILIP BALL © Nature News Service

All latest news from the category: Physics and Astronomy

This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.

innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.

Back to home

Comments (0)

Write a comment

Newest articles

Researchers shrink camera to the size of a salt grain

Micro-sized cameras have great potential to spot problems in the human body and enable sensing for super-small robots, but past approaches captured fuzzy, distorted images with limited fields of view….

World-first product will be a lifesaving traffic stopper

Game-changing technology to design traffic lights that absorb kinetic energy, stopping them from crumpling when hit by a vehicle, will prevent thousands of fatalities and injuries each year and make…

Scientists capture electron transfer image in electrocatalysis process

The involvement between electron transfer (ET) and catalytic reaction at electrocatalyst surface makes electrochemical process challenging to understand and control. How to experimentally determine ET process occurring at nanoscale is…

Partners & Sponsors