  Analysis of nanoscale liquids, including wetting and flow phenomena, is a
scientific challenge with far reaching implications for industrial
technologies. We report the conception, development, and application of an
integrated platform for the experimental characterization of liquids at the
nanometer scale. The platform combines the sensing functionalities of an
integrated, two-dimensional electronic device array with in situ application of
highly sensitive optical micro-spectroscopy and atomic force microscopy. We
demonstrate the performance capabilities of the platform with an embodiment
based on an array of integrated, optically transparent graphene sensors. The
application of electronic and optical sensing in the platform allows for
differentiating between liquids electronically, for determining a liquid's
molecular fingerprint, and for monitoring surface wetting dynamics in real
time. In order to explore the platform's sensitivity limits, we record
topographies and optical spectra of individual, spatially isolated sessile oil
emulsion droplets having volumes of less than ten attoliters. The results
demonstrate that integrated measurement functionalities based on
two-dimensional materials have the potential to push lab-on-chip based analysis
from the microscale to the nanoscale.
