April 27, 2009

Nanocantilevers eliminate transducers

U.S. scientists say they have created silicon-based nanocantilevers, smaller than the wavelength of light, eliminating the need for electric transducers.

Yale University researchers said the nanocantilevers operate on photonic principles, providing new tools for ultra-sensitive measurements at the atomic level.

In nanoelectromechanical systesm, cantilevers -- fixed at one end and free at the other -- act like nano-scale diving boards that bend when molecules jump on them and register a change that can be measured, the scientists said.

The system we developed is the most sensitive available that works at room temperature, said Assistant Professor Hong Tang. Previously this level of sensitivity could only be achieved at extreme low temperatures.

He said the system can detect as little deflection in the nano-cantilever sensors as 0.0001 Angstroms -- one ten thousandth of the size of an atom. To detect such tiny motion, the researchers devised a photonic structure to guide the light wave through a cantilever. After exiting from the free end of the cantilever, the light tunnels through a nanometer gap and is collected on chip. Detecting the light wave after this evanescent tunneling, said Tang, gives the unprecedented sensitivity.

The work is reported in the early online edition of the journal Nature Nanotechnology.