London, Dec 2 (PTI) Scientists, including one of Indianorigin, have developed tiny electronic "tweezers" usinggraphene that can efficiently grab biomolecules floating inwater, an advance that may lead to a handheld diseasedetecting system.
Graphene, a material made of a single layer of carbonatoms, was discovered more than a decade ago and hasenthralled researchers with its range of amazing propertiesthat have found uses in many new applications frommicroelectronics to solar cells.
The graphene tweezers developed at the University ofMinnesota in the US are vastly more effective at trappingparticles compared to other techniques used in the past due tothe fact that graphene is a single atom thick, less than onebillionth of a metre.
The physical principle of tweezing or trappingnanometre-scale objects, known as dielectrophoresis, has beenknown for a long time and is typically practiced by using apair of metal electrodes.
From the viewpoint of grabbing molecules, however, metalelectrodes are very blunt. They simply lack the "sharpness" topick up and control nanometre-scale objects.
"Graphene is the thinnest material ever discovered, andit is this property that allows us to make these tweezers soefficient. No other material can come close," said Sang-HyunOh, professor at the University of Minnesota.
"To build efficient electronic tweezers to grabbiomolecules, basically we need to create miniaturisedlightning rods and concentrate huge amount of electrical fluxon the sharp tip. The edges of graphene are the sharpestlightning rods," said Oh.
The team also showed that the graphene tweezers could beused for a wide range of physical and biological applicationsby trapping semiconductor nanocrystals, nanodiamond particles,and even DNA molecules.
Normally this type of trapping would require highvoltages, restricting it to a laboratory environment, butgraphene tweezers can trap small DNA molecules at around oneVolt, meaning that this could work on portable devices such asmobile phones.
Researchers made the graphene tweezers by creating asandwich structure where a thin insulating material callhafnium dioxide is sandwiched between a metal electrode on oneside and graphene on the other.
Hafnium dioxide is a material that is commonly used intoday's advanced microchips.
"One of the great things about graphene is it iscompatible with standard processing tools in the semiconductorindustry, which will make it much easier to commercialisethese devices in the future," said Koester, who led the effortto fabricate the graphene devices.
"Since we are the first to demonstrate such low-powertrapping of biomolecules using graphene tweezers, more workstill needs to be done to determine the theoretical limits fora fully optimised device," said Avijit Barik, graduate studentat University of Minnesota.
"For this initial demonstration, we have usedsophisticated laboratory tools such as a fluorescencemicroscope and electronic instruments," said Barik, leadauthor of the study published in Nature Communications.
"Our ultimate goal is to miniaturise the entire apparatusinto a single microchip that is operated by a mobile phone,"he said. PTI MHNMHN.
This is unedited, unformatted feed from the Press Trust of India wire.