  We measured the conductance fluctuation of bi- and trilayer graphene devices
prepared on mechanical exfoliated graphene by an all-dry, lithography-free
process using an ultrathin quartz filament as a shadow mask. Reproducible
fluctuations in conductance as a function of applied gate voltage or magnetic
field were found. As the gate voltage was tuned so that the graphene device was
pushed to the charge neutral point, the amplitude of the conductance
fluctuation was found to be suppressed quickly from a value consistent with
universal conductance fluctuation when the devices were still well within
weakly disordered regime. The possible physical origins of the suppression are
discussed.
