"Lightweight and highly flexible CNT-composites provide fast electrothermo-actuation at low power," Weileun Fang told nanotechweb.org. "Moving the actuator from its original position to its pull-in position can be employed to define two different states such as 0/1 or on/off, which suits many applications in communications and displays."

The group's nanocomposite device has a pull-in voltage of just 50 V for a full deflection of 560 µm. As Fang explains, this value is very low compared with existing microcantilevers, which can demand at least 500 V to achieve a similar displacement. The researchers believe that CNT-based field amplification is responsible for the low pull-in voltage.

Next, the group turned its attention towards the actuator's damping properties. Images show that the aligned nanotubes are curled into spring-like structures that act as energy absorbers and help to reduce beam oscillation.

To make their composite material, the researchers first grow multiwalled CNTs on a iron-defined polysilicon substrate and then expose the substrate to polymer vapour. The CNT-polymer actuators are formed by removing the underlying polysilicon with vapour-phase XeF2.

The researchers presented their work in Nanotechnology.