  The widespread application of surface-attached nanobubbles and nanodroplets
in biomedical engineering and nanotechnology is limited by numerous
experimental challenges, in particular, the possibility of contamination in
nucleation experiments. These challenges are complicated by recent reports that
it can be difficult to distinguish between nanoscale drops and bubbles. Here we
identify clear differences in the mechanical responses of nanobubbles and
nanodroplets under various modes of AFM imaging which subject the objects to
predominantly vertical or lateral forces. This allows to distinguish between
nanodroplets, nanobubbles, and oil covered nanobubbles in water.
