There are billions of small transistors crammed inside computer chips, which enable powerful computing but also generate a great deal of heat. The accumulation of heat in a computer processor can reduce its performance and reliability. Engineers use heat sinks, sometimes in conjunction with fans or liquid cooling systems, to keep chips cool; nevertheless, these technologies frequently demand a great deal of energy to run.
Massachusetts Institute of Technology (MIT) researchers have taken a different method. They devised an algorithm and software system that can autonomously construct a nanoscale material capable of conducting heat in a certain manner, such as by channelling heat in only one direction. Because these materials are measured in nanometers (a human hair is around 80,000 nanometers broad), they could be employed in computer chips that can naturally disperse heat due to the geometry of the material.
The researchers created their method by adopting computational approaches normally used to generate big structures to produce nanoscale materials with specified thermal properties. They made a material that can move heat in a preferred direction (this is called “thermal anisotropy”) and another that can turn heat into electricity in an efficient way. At MIT.nano, they are using the second design to make a nanostructured silicon device for recovering heat from waste heat.
Scientists usually use a mix of guesswork and trial and error to figure out how to improve the way a nanomaterial conducts heat. Instead, a person could put the thermal properties they want into a software system and get a design that can achieve those properties and could be made.
In addition to making computer chips that can get rid of heat, this method could also be used to make thermoelectric materials, which efficiently turn heat into electricity. The lead author, Giuseppe Romano, is a research scientist at MIT’s Institute for Soldier Nanotechnology and a member of the MIT-IBM Watson AI Lab. He says that these materials could use the waste heat from a rocket’s engines to help power a spacecraft.
Heat moves through semiconductors by way of vibrations. When molecules get hotter, they vibrate faster, which makes nearby groups of molecules start to vibrate, and so on. This moves heat through a material like a crowd of baseball fans doing “the wave.” At the level of the atom, these vibrational waves are turned into discrete packets of energy called “phonons.”
The ability to modify how heat can go through a material by making some portions of these structures too thin for phonons to pass through is theoretically possible. However, there are almost innumerable configurations, so it would have been incredibly impossible to arrange them for specified thermal qualities simply using intuition.
Hence, the researchers developed a novel technique, known as the transmission interpolation method, that allows these extremely complex equations to behave in a manner that the algorithm can manage. Using this technology, the computer may deform the material distribution constantly and smoothly until it obtains the necessary thermal characteristics, as opposed to testing each pixel individually.
The researchers also developed an open-source software system and a web application that allow users to input their desired thermal parameters and receive a nanoscale material structure that can be manufactured. The researchers believe that making the system open source will encourage other scientists to contribute to this field of study.
With this new instrument in hand, the researchers are investigating other materials, such as metal alloys, that can be tuned using this technique, which could open the door to new uses. Additionally, they are investigating strategies for optimising heat conductivity in three dimensions, not just horizontally and vertically.