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NanoElectroMechanical Systems based on Carbon Nanotube and Graphene

Final Report Summary - CARBONNEMS (NanoElectroMechanical Systems based on Carbon Nanotube and Graphene)

Mechanical resonators based on carbon nanotubes and graphene feature a series of truly exceptional properties. Carbon nanotubes are so small that they make the lightest resonators fabricated thus far. In addition, we showed that the quality factor Q becomes extremely large at cryogenic temperature, up to 5 million. As for graphene, we recently achieved Q-factors surpassing 1 million. These values are comparable to the highest Q-factors reported in mechanical resonators of much larger size. The demonstration of such large quality factors came as a surprise. For many years, researchers observed that quality factors would decrease with the volume of the resonator, and because of this trend it was unthinkable that nanotubes and graphene could exhibit such giant quality factors. This large Q-factor reflects the high crystallinity of these materials and their lack of dangling bonds at the surface. In other nanomechanical systems, dangling bonds are often an important source of dissipation.

Because of this combination of low mass and high quality factor, nanotube/graphene resonators are exceptional sensors of mass and force. We developed new schemes in order to probe thermal vibrations of these resonators. Using sideband cooling, we were able to detect down to 7 phonons. The mass resolution can be as low as 1.7 yg (1.7·10-24 g), which corresponds to the mass of one proton. This mass resolution is more than 1000 times better than what can be achieved with other resonators. The force noise can be as low as 1 zN/Hz0.5 where 1 zN=10-21 N. This is 500 times lower than the force sensitivity obtained with other resonators.

We developed catalytic engines that use hydrogen peroxide as a chemical fuel in order to drive motion at the microscale. We showed that catalytic pumps based on silicon/metal structures and actuated through light-activated chemical reactions are highly efficient. We employed these pumps to manipulate colloids in an autonomous fashion. We demonstrated that the manipulation reaches a level of complexity not achieved before. Indeed, we show that catalytic pumps can perform sequentially in time different types of manipulation. This includes repulsion of colloids, attraction of colloids, and crystallization of colloids.