A team of Russian and Australian scientists have developed a novel black silicon ultra-sensitive sensor for detecting explosives.
According to Russia’s Far Eastern Federal University (FEFU) and Australia’s Melbourne Center for Nanofabrication, the new device can detect trace amounts of nitroaromatic compounds and could also be applied to identify the majority of explosives, or highly toxic pollutants for medical and forensic evaluations.
The black silicon sensor was fabricated using high-performing reactive etching of commercially available silicon substrates. Such etched silicon has a nanostructured spiky surface exhibiting unique optical properties.
After etching, the surface was covered with a monolayer of carbazole molecules. This process is called chemical functionalization since the attached molecules impart the substrate a certain important function, namely, the ability to bind and concentrate nitroaromatic compounds on the surface.
According to the scientists, the carbazole monolayer renders the device sensitive to such widely spread nitroaromatic substances such as nitrobenzene, o-nitrotoluene, 2.4-dinitrotoluene, etc.
It does not however react to the presence of other molecules, such as benzene, toluene, tetrachloromethane, methanol, ethanol, and so on.
“Nitroaromatic compounds can be found in the waste waters of paint plants or military facilities and are extremely dangerous for the environment. Moreover, they are parts of many explosives as well,” contends FEFU research associate Alexander Kuchmizhak.
“Their detection in trace concentration represents an important and complex practical task. Our sensor platform identifies the presence of nitroaromatic compounds by means of registering the changes in the luminescence spectrum of the functional layer of carbazole that selectively reacts to nitroaromatic molecules.”
According to Kuchmizhak, the nanostructured black silicon used as the basis of the device gives it high sensitivity and an unprecedented dynamic measurement range.
The sensor – designed by senior research associate Alexander Mironenko – has so far proven to be quite adept at providing information about the presence of toxic molecules in liquids or gases within a few minutes.
The teams have also stated that the manufacture of the new sensor platform should be a lot cheaper when compared to existing analogs.
An added plus is that the same sensor can be used multiple times; it could in the longer run become a part of gas sensor systems that secure public and ecological safety.
Image and content: FEFU via eurekalert