Here comes a new technology that may control the flow of heat the way electronic devices control electrical current - a discovery that could have applications in a diverse range of fields from electronics to textiles.
In most systems, heat flow is equal in both directions, so there are no thermal devices like electrical diodes.
"If we are able to control heat flow like we control electricity using diodes, then we can enable new and exciting thermal devices including thermal switches, thermal transistors, logic gates and memory," said Xiulin Ruan, an associate professor in Purdue University's school of mechanical engineering.
The concept uses tiny triangular structures to control 'phonons', quantum-mechanical phenomena that describe how vibrations travel through a material's crystal structure.'
Rectification has made possible transistors, diodes and memory circuits central to the semiconductor industry.
The new devices are thermal rectifiers that might perform the same function, but with phonons instead of electrical current.
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The researchers used an advanced simulation method called molecular dynamics to demonstrate thermal rectification in structures called 'asymmetric graphene nanoribbons'.
Molecular dynamics simulations can simulate the vibrations of atoms and predict the heat flow in a material.
Graphene, an extremely thin layer of carbon, is promising for applications in electronics and computers, said the study appeared in the journal Nano Letters.
Findings also show thermal rectification is not limited to graphene but could be seen in other materials in structures such as pyramidal, trapezoidal or T-shaped designs.
"People are just starting to understand how it works, and it is quite far from being used in applications," added Yong Chen, an associate professor in Purdue's department of physics.