New black silicon-based ultrasensitive detector can detect toxic compounds

Market Expertz   |     December 02, 2019


A team of researchers from the Far Eastern Federal University (FEFU), Swinburne University of Technology, Far Eastern Branch of the Russian Academy of Sciences, and Melbourne Center for Nanofabrication have built an ultrasensitive detector using black silicon. The device can detect trace amounts of nitroaromatic compounds and can also identify most explosives or highly toxic pollutants for medical and forensic evaluations. The novel sensor is built with the so-called ‘black silicon,’ which is made by high-performing reactive etching of commercially available silicon substrates. This kind of etched silicon possesses a nanostructured spiky surface with distinct optical properties.

Following the etching, the surface is coated with a monolayer of carbazole molecules in a process known as ‘chemical functionalization,’ wherein the attached molecules give the substrate the ability to bind and concentrate nitroaromatic compounds on the surface. The carbazole monolayer makes the device susceptible to similar nitroaromatic substances like 2.4-dinitrotoluene, nitrobenzene, and o-nitrotoluene, among others. However, the sensor is unable to detect the presence of other molecules like benzene, ethanol, methanol, toluene, and tetrachloromethane, among others. Alexander Kuchmizhak, Research Associate, VR and AR Center of the Science and Technology, FEFU, says that these compounds are present in wastewater from paint plants or military facilities and are hazardous to the environment. They are also one of the components in many types of explosives, and it can be tough to detect traces of the compounds but is a crucial task.

The new sensor platform can detect traces of nitroaromatic compounds by registering the changes in the luminescence spectrum of the carbazole monolayer that particularly reacts to nitroaromatic molecules, explains Kuchmizhak. Nanostructured black silicon used to build the device gives it high sensitivity and a unique dynamic measurement range. In the lab, the sensor was able to extract information about the presence of toxic molecules in liquids or gases in a few minutes. The researchers say that the same sensor can be used multiple times and might potentially be used as part of gas sensor systems.

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