  We perform both molecular dynamics simulations and theoretical analysis to
study the sensitivity of the graphene nanomechanical resonator based mass
sensors, which are actuated following the global extended mode or the localized
edge mode. We find that the mass detection sensitivity corresponding to the
edge mode is about three times higher than that corresponding to the extended
mode. Our analytic derivations reveal that the enhancement of the sensitivity
originates in the reduction of the effective mass for the edge mode due to its
localizing feature.
