If the terrorist attacks at the airports are to be prevented, low concentrations of chemicals and explosives have to be detected easily. Apart from the development of different sensor technologies, dogs can be regarded as a good detector. A team of German and French researchers claim that they have invented a kind of micromechanical sensor. These sensors are derived from the sense organs of butterflies.
These sensors are based on the idea of microcantilevers. These microcantilevers are a sort of tiny flexible cantilevers. They are like the atomic force microscopes which are used to scan surfaces. The microcantilevers have a coating of a particular material which binds to the detected analytes. Like springs, these cantilevers also vibrate. When these analyte molecules get bounded to the microcantilever, with the vibration frequency, its mass changes. You can measure this change of mass.
At the room temperature, due to the very low vapor pressure, it is a big challenge to reliably detect these highly sensitive detectives. To make this microcantilevers more sensitive than TNT (trinitrotoluene), a group of researchers have taken inspiration from some butterfly’s sensitive sense organs.
The microcantilevers are equipped like the antenna of the butterflies. Scientists use three-dimensional layer of titanium dioxide nanotubes for coating of this microcantilevers. By doing this, there are several advantages.
- The microcantilever’s specific surface area is notably increased.
- Those substances which contain nitro groups like TNT get bounded well with titanium dioxide.
- These nanotubes consist of open structure which does a rapid response of sensors and movement of mass.
These nanotubes are of 1700 nm dimensions & they have an outer diameter of around 100 nm and of 20 nm wall thickness. About 500,000 of these nanotubes can be holded by each cantilever.
Researchers heat each tiny crystal to vaporize TNA. This is done for testing purpose only. As a result, the sensors were able to detect less than 1ppt (part per trillion) of concentrations within a short time. Nowadays, researchers are trying to develop an advance detector system based on this intelligent method.
It can be said that researchers are trying hard to detect tiny amount of explosives with nanotech devices. Carbon nanotubes are used in this regard.