Ultra-sensitive analysis of a cantilevered single-walled carbon nanocone-based mass detector.

The ultra-sensitivity of mass detectors using individual cantilevered single-walled carbon nanocone (SWCNC) resonators is first investigated. A higher-order gradient theory, derived at the atomic level, is applied for modeling SWCNC resonators. Numerical simulations using a mesh-free computational framework based on moving Kriging interpolation are conducted to investigate the mass sensitivity of cantilevered SWCNC resonators with extra mass loading as well as with equivalent single-walled carbon nanotube (SWCNT) resonators. Comparison of the magnitude of resonant frequency shifts, the key criterion for mass sensitivity, of these two kinds of resonators demonstrates a far higher mass sensitivity for SWCNC resonators than for SWCNT resonators, thus suggesting a new method for ultra-sensitive mass detection via SWCNC resonators. The dependence of the mass sensitivity of SWCNC resonators on height and top radii has been examined. A reduction in the height of SWCNC resonators gives rise to a considerable increase in mass sensitivity. The mass sensitivity of a 6 nm high SWCNC resonator can even reach a level of 10(-22) g. It is noteworthy that the top radii of SWCNC resonators have a slight effect on frequency shifts. Another interesting observed phenomenon is that a deviation in the height of 19.2° SWCNC resonators leads to little loss in precision of mass detection when the attached mass is smaller than 10(-20) g. This superior characteristic indicates that SWCNC-based mass detectors have great potential in practical applications.