A sensing method includes exposing a nano-transducer having a controlled
surface to a sample including at least one species. Adsorption of the
species on the nano-transducer is transduced to a measurable signal as a
function of time. Desorption of the species from the nano-transducer is
also transduced to a measurable signal as a function of time. A residence
time of the at least one species adsorbed on the nano-transducer is
extracted from the measurable signals. The adsorption and desorption each
define an individual measurable event.