Graphene mechanical resonators have recently attracted considerable attention for use in precision force and mass sensing applications. To date, readout of their oscillatory motion has typically required cryogenic conditions to achieve high sensitivity, restricting their range of applications. Here we report the first demonstration of evanescent optical readout of graphene motion, using a scheme which does not require cryogenic conditions and exhibits enhanced sensitivity and bandwidth at room temperature. We utilise a high Q microsphere to enable evanescent readout of a 70 μm diameter graphene drum resonator with a signal-to-noise ratio of greater than 25 dB, corresponding to a transduction sensitivity of SN1/2= 2.6 ×10−13 m Hz−1/2. The sensitivity of force measurements using this resonator is limited by the thermal noise driving the resonator, corresponding to a force sensitivity of Fmin=1.5×10−16 N Hz−1/2 with a bandwidth of 35 kHz at room temperature (T = 300 K). Measurements on a 30 μm graphene drum had sufficient sensitivity to resolve the lowest three thermally driven mechanical resonances.
@article{arxiv.1408.1281,
title = {Evanescent field optical readout of graphene mechanical motion at room temperature},
author = {Robin M. Cole and George A. Brawley and Vivek P. Adiga and Roberto De Alba and Jeevak M. Parpia and Bojan Ilic and Harold G. Craighead and Warwick P. Bowen},
journal= {arXiv preprint arXiv:1408.1281},
year = {2014}
}