Nanorelay race is on 
6 March 2003 

Scientists at Chalmers University of Technology in Sweden have theoretically modelled the properties of a nanorelay device. The nanorelay consisted of a conducting carbon nanotube beam, a stepped silicon substrate and three electrodes.

"These results describe a basic idea, a way of building a nanoelectromechanical switch using small conducting cantilevers such as metallic nanotubes," researcher Jari Kinaret told nanotechweb.org. "The main aim with this first publication was to get the idea out in order to stimulate experimental work on nanorelays." 

In the scientists' simulation, the fixed end of the nanotube beam connects to a source electrode, while a drain electrode sits beneath the other end of the tube. Applying a voltage to a gate electrode positioned roughly below the beam's midpoint induces a charge in the nanotube and makes it bend. As a result, the free end of the tube touches the drain electrode, acting as a switch to close an electric circuit. 

In the real world, the devices could have applications as logic devices, pulse generators, current or voltage amplifiers, and memory elements. 

"Since there are different types of forces acting on the nanorelay - mechanical restoring forces and electrostatic forces - with different dependences on the cantilever deflection, there is the possibility of two stable shapes of the tube (strongly and weakly bent)," continued Kinaret. "These two states exhibit different conductances and can be used to build a nanoelectromechanical memory element." 

And, Kinaret reckons the device could also form a nanoelectromechanical amplifier, since the conductance of the system is very sensitive to the amount of tube deflection. 

Now the team is investigating the effect of short-range interactions between the nanotube and drain electrode on the nanorelay's characteristics, as well as determining the best nanorelay designs for different applications, particularly the memory cell. "In the near future we expect to have access to the first experimental results by our colleagues, and after that we will pursue the work in a close collaboration with them," added Kinaret. 

The researchers, who reported their work in Applied Physics Letters, received funding from Sweden's CARAMEL (Carbon Allotropes for Microelectronics) research programme.

About the author

Liz Kalaugher is editor of nanotechweb.org.