Real-Time Mass Sensing of a Flux of Incoming Particles.

We present a theoretical framework for determining the mass deposited on a mechanical resonator subject to a flux of incoming particles of a single species. We consider the specific example of a vibrating nanostring and infer the history of mass deposition events from the frequency shifts in real time using a numerical optimization alogrithm that correctly compensates for the configurational entropy. Our approach is tested against simulated data and is shown to perform well.