Mechanical resonators are extensively used in high-tech industry, to mark time in electronic components, and to stabilize radio transmissions. Most mechanica-l resonators damp (slow down) in a well-understood linear manner, but ground- breaking work by Prof. Adrian Bachtold and his research group at the Catalan In-stitute of Nanotechnology has shown that resonators formed from nanoscale gra-phene and carbon nanotubes exhibit nonlinear damping, opening up exciting pos-sibilities for super-sensitive detectors of force or mass.

In an article recently published in Nature Nanotechnology Prof. Bachtold and his co-researchers describe how they formed nano-scale resonators by suspending ti-ny graphene sheets or carbon nanotubes and clamping them at each end. These devices, similar to guitar strings, can be set to vibrate at very specific frequenci-es.

In all mechanical resonators studied to date, from large objects several metres in size down to tiny components just a few tens of nanometers in length, dampi-ng has always been observed to occur in a highly predictable, linear manner. Ho-wever Prof. Bachtold丩s research demonstrates that this linear damping paradig-m breaks down for resonators with critical dimensions on the atomic scale. Of particular importance they have shown that the damping is strongly nonlinear f-or resonators based on nanotubes and graphene, a characteristic that facilitates amplification of signals and dramatic improvements in sensitivity.

The finding has profound consequences. Damping is central to the physics of na-noelectromechanical resonators, lying at the core of quantum and sensing exper-iments. Therefore many predictions that have been made for nanoscale electrom-echanical devices now need to be revisited when considering nanotube and grap-hene resonators.

This new insight into the dynamics of nano-scale resonators will also enable dra-matic improvements in the performance of numerous devices. Already the Prof. Bachtold丩s group has achieved a new record in quality factor for graphene reso-nators and ultra-weak force sensing with a nanotube resonator.

The work is particularly timely because an increasing number of research groups around the world with diverse backgrounds are choosing to study nanotube/grap-hene resonators, which have a number of uniquely useful properties.