The Use of Quantum Dots in The Production Of Nanosensors

Quantum dots are defined as small semiconductor crystals. By controlling the dimensions of the quantum dots, the electromagnetic field emits light in  different colors and wavelengths. For example, quantum dots made of cadmium arsenide with dimensions of 3 nm emit green light; While  particles with a size of 5.5 nanometers of the same material emit red light. Due to the ability to produce light at specific wavelengths of quantum dots,  these tiny crystals are used in optical devices. In this field, quantum dots can be used in making infrared detectors, light emitting diodes  . Infrared detectors are extremely important. The main problem of these detectors is their cooling  . Liquid oxygen and electronic cooling are used to cool these detectors. These detectors  must work at very low temperatures, close to 31 degrees Kelvin, to function properly, so they cannot be used at room temperature, while detectors  made using quantum dots can be easily used at room temperature.

The use of nanotubes in the production of nanosensors

Due to their unique mechanical and electronic properties, single-walled and multi-walled carbon nanotubes have found various applications,  including their use as sensors with very high accuracy to detect substances at very low concentrations and at high speeds.  did

In general, the use of nanotubes in sensors can be divided into two categories:

A ) Carbon nanotubes as chemical sensors: These sensors can  detect very small concentrations of gas molecules with very high sensitivity at room temperature. Chemical sensors include collections of single-walled nanotubes and can detect chemicals  such as nitrogen dioxide and The electrical conductivity of a single-walled semiconductor nanotube  placed in the vicinity of 0.11 ppm of nitrogen dioxide can be tripled within seconds, and the conductivity  will double for adding just 0% ammonia. Sensors made of single-walled nanotubes have high sensitivity and quick response at room temperature.These  properties have important results in diagnostic applications.

b) Carbon nanotubes as mechanical sensors: When a nanotube is moved up or down by an object,  its electrical conductivity changes. This change in electrical conductivity is completely proportional to the mechanical deformation of the nanotube. This measurement is The clarity shows the possibility of using nanotubes as mechanical sensors, or by using intermediate materials such as polymers in the distance between carbon nanotubes and the system, carbon nanotubes can be developed to make biosensors Polymers such as polyethylene can be chemically bonded to carbon nanotubes. Also, benzene molecules can be adsorbed on carbon nanotubes. This research shows the wide range of applications of carbon nanotubes.