Researchers at UCLA have created what they have termed the world’s smallest refrigerator. When most of us think of a fridge, we think of the machine sitting in the kitchen that keeps meat frozen and milk cold. What the researchers at UCLA created isn’t a traditional refrigerator. It’s a thermoelectric cooler only 100 nanometers thick.
The device is made by sandwiching two different semiconductors between metalized plates. When heat is applied, one side of the plate becomes hot, and the other remains cool. That temperature difference can be used to generate electricity. Scientific instruments and spacecraft, such as Voyager, have used this technology to generate power for roughly four decades using thermoelectric devices wrapped around heat-producing plutonium.
Researchers believe that these devices have uses here on Earth and include uses such as capturing heat from an exhaust system of the car to power other systems on the vehicle. The process does work in reverse, when an electrical current is applied to the device, one side becomes hot, and the other becomes cold, enabling it to serve as a cooler or refrigerator. Scientists believe that if the technology was scaled up, it could replace the vapor-compression system in the fridge in the kitchen.
The device is created using a pair of standard semiconductor materials, including bismuth telluride and antimony-bismuth telluride. In the building process, researchers attached regular Scotch tape to chunks of both materials, pulled it off, and harvested the single-crystal flakes from the material stuck to the tape. Those thin flakes were used to create the functional devices that are only 100 nanometers thick and have a total active volume of about one cubic micrometer, invisible to the naked eye.
The researchers hope to discover new ways to synthesize higher performance bulk materials. One key feature of the tiny refrigerator the team created is that it can respond almost instantly. Researchers say that its small size makes it millions of times faster than a fridge with a volume of a millimeter cubed.