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Posted: November 6, 2008

Semiconductor nanocrystals research boosts the search for sensitive sensors

(Nanowerk News) Research that could lead to brighter LCD screens, more efficient solar panels, improved biomedical imaging and high-tech security sensors has won the University of Melbourne's Chancellor's Prize for Excellence in PhD.
Dr Daniel Gomez, who completed his thesis in the School of Chemistry, has shed new light on the properties of semiconductor nano-crystals, particles only a billionth of a metre long.
He is now expanding on his work as a Research Fellow at CSIRO where he is part of a team that is working to develop new sensor applications.
Dr Gomez is working on the "fundamental science" aspect of the project – determining how to incorporate these nano-crystals as highly sensitive components in a variety of sensor devices.
With this sensing technology, it would be possible to detect very small amounts of dry particles – such as biological agents or explosives – in the air or liquid.
They could even result in more sensitive pathology, detecting minute amounts of drugs or hormonal changes in urine tests.
Dr Gomez's PhD at the University of Melbourne examined the optical properties of nano-cystals of cadmium selenide, an element commonly used by the semiconductor industry.
"When pieces of matter become smaller they change color,'' he says. "If you look at them individually against a dark background they blink like stars against the night sky. "Typically this blinking is random, just like the night sky with the stars twinkling in green, red and blue."
Dr Gomez's thesis aimed to pinpoint the factors that contributed to this blinking and determine which chemicals could be added to switch the blinking off.
It was hoped that by modifying the surface of the nano-particles they could eventually be stabilised to emit a single, brighter source of light.
Although Dr Gomez has yet to completely achieve his goal, his research was the first in the world to show that the blinking of nano-crystals could be controlled.
During his PhD candidature he published nine articles in premier scientific journals and an international examiner described his work "as one of the best studies I have ever seen".
Dr Gomez, an international student from Venezuela, set his sights on studying at Melbourne because of the international reputation of his supervisor Professor Paul Mulvaney.
His Chancellor's Prize for Science and Engineering will be presented at the University's Menzies Oration tonight (6 November).
Source: University of Melbourne