Nanosensors and properties of carbon nanotubes (CNTs) Nanomicroelectronics

Note: The electronic properties of carbon nanotubes are highly sensitive to the chemical environment surrounding the nanotubes. This sensitivity is a suitable tool for using nanotubes in the sensing sector.

Nanosensors using single-walled carbon nanotubes Semiconductors Using electronic conduction, which  is grown by CVD on a substrate and  connecting a wire to the nanotubes and creating a metal/nanotube/metal structure, a nanotransistor can be made that can  change conductivity when different voltages are applied. The electrical conductivity of these nanotubes   is used in the structure of single-walled   carbon nanotube  electronic nanosensors and nanosensors. A hole-doped semiconductor that reduces electrical conductivity threefold  when a positive gate voltage is applied to  this nanosensor system. In the presence of electronic conduction, the valence band of the nanotube moves away from the Fermi level,  which leads to a decrease in the number of holes and, as a result, a decrease in electronic conduction  .  The Fermi energy of CNT nanotubes and CNTs shifts to the valence band. This  increases the concentration of holes in the nanotube, thereby improving the electrical conductivity in the nanosensors.

Carbon nanotubes have a fullerene-like structure that can be capped at the ends. These nanostructures are named after their physical form, in which a graphene sheet is rolled up with different rolling angles to form tubes with  different symmetries. The rolling angle and  radius of the tube determine whether  these nanostructures exhibit metallic or semiconducting properties. Nanotubes  are divided into two groups: single-walled carbon nanotubes  (SWCNTs) and multi-walled carbon nanotubes  (MWCNTs). In multi-walled nanotubes, multiple graphene sheets are rolled up. Carbon nanotubes naturally stick together due to van der Waals attraction.

Conclusion :

Nanosensors based on  single-walled carbon nanotubes (SWNTs) are less sensitive than devices containing individual nanotubes. This is  because in bulk SWNTs,  the effects of molecular interactions are less than in metallic and semiconductor nanotubes.  Also, the internal tubes in SWNT strands are unable to interact with  gases; this is because molecules cannot  penetrate between the SWNT strands.