Engineers have produced a thermocouple of graphene, forming it into the shape of the letter P, although typically, this use of two different materials. It is possible to increase the sensitivity to temperature, to reduce the size and simplify the production, which will allow you to use the invention in the thermometer in nanoscale electronics. Article published in the journal Advanced Functional Materials.
If solder wire of different metals, such as iron and copper, and the place of soldering heat, then due to the Seebeck effect there current. This device is called a thermocouple, and the current in it depends on the temperature difference between risers and connection. Therefore, knowing the temperature of a single point, we can calculate the temperature of the second.
Thermocouples are being widely used for temperature control due to its simplicity, accuracy, reliability and a wide measuring range. In particular, they are used in the CPU in case of overheating in time to turn the device off or decrease the load. The problem is that the traditional thermocouple of different metals is not possible in the normal course of the manufacturing process of the chips, and therefore it is necessary to organize a second individual, due to which the design udorozhaet and complicated.
Harim akim (Achim Harzheim) from Oxford University and his colleagues invented a new type of thermocouple. They decided to use two different materials, a single, but complex forms. The fact that the emergence of the current two conductors should have different Seebeck coefficient. It is different for different metals, but in the case of very thin flat materials also depends on their width. This is because this ratio is affected by the free path length of electrons in the material, and the cut is, the stronger is reduced mileage due to the scattering of electrons on the faces. Consequently there is a very thin conductors of different widths can occur to the thermoelectric effect.
To implement this conducted experiments with different metals, but of the thermocouple based on them are obtained too large with a length of hundreds of microns, and their sensitivity is unsatisfactory. Therefore, the scientists decided as a flat conductor to use graphene. The resulting device has a length of approximately four microns, and is shaped like an asymmetrical letter P.