Scientists at the University of California, Los Angeles (UCLA) have come up with what is being deemed as ¡±the world¡¯s smallest refrigerator.¡± The new device is only 100 nanometers thick - roughly one ten-millionth of a meter in size.
In essence, the device is a unique thermoelectric cooler in a miniscule size. These are not ¡°refrigerators¡± in the everyday sense but the same technology is used at larger scales for cooling purposes. These use cases include cooling electronic devices,?regulating temperature?in fiber-optic networks as well as reducing image ¡°noise¡± in?high-end telescopes?and digital cameras.
¡°We have made the world¡¯s smallest refrigerator,¡± said Regan, the lead author of a paper on the research. In addition to the thermoelectric cooler, the study also mentions an innovative technique for measuring their cooling performance. The research has now been published in the journal ACS Nano.
Thermoelectric coolers, like the one created by the team of UCLA scientists, are made by sandwiching two different semiconductors between metalized plates. There are two ways in which the devices work. One, they use temperature difference to create electricity and the other - they use electricity to generate temperature difference, essentially like in a refrigerator.
For the first part, heat applied to one part of thermoelectric devices results in a temperature difference as the other side remains cool. This temperature difference can then be used to generate electricity. Such applications are seen on numerous scientific instruments used in outer space missions.
When the process is reversed, an electrical current is applied to the device to make one side of it hot and the other cold. The device then acts as a cooler or refrigerator. Though this is a different cooling technique than the vapor-compression system used in your fridge, it might one day be scaled up for the same use.
Regan, along with six UCLA undergraduates as his team, used two standard semiconductor materials - bismuth telluride and antimony-bismuth telluride, for the thermoelectric cooler. But instead of using sheets of the materials directly, the team attached regular Scotch tape to them, peeled it off and then harvested ¡°thin, single-crystal flakes from the material still stuck to the tape.¡±?
The new and unique functional devices were then created from these miniscule flakes. The result was a 100 nanometers thick thermoelectric device with a total active volume of about 1 cubic micrometer, invisible to the naked eye.
¡°We beat the record for the world¡¯s smallest thermoelectric cooler by a factor of more than ten thousand,¡± said Xin Yi Ling, one of the paper¡¯s authors.