In many cases in experimental science, the instrument interface
becomes a limiting factor in the efficacy of carrying out unusual
experiments or prevents the complete understanding of the acquired data.
We have developed an advanced interface for scanning probe microscopy
(SPM) that allows intuitive rendering of data sets and natural instrument
control, all in real time. The interface, called the nanoManipulator,
combines a high-performance graphics engine for real-time data rendering
with a haptic interface that places the human operator directly into the
feedback loop that controls surface manipulations. Using a hand-held
stylus, the operator moves the stylus laterally, directing the movement of
the SPM tip across the sample. The haptic interface enables the user to
“feel” the surface by forcing the stylus to move up and down
in response to the surface topography. In this way the user understands
the immediate location of the tip on the sample and can quickly and
precisely maneuver nanometer-scale objects. We have applied this interface
to studies of the mechanical properties of nanotubes and to
substrate-nanotube interactions. The mechanical properties of carbon
nanotubes have been demonstrated to be extraordinary. They have an elastic
modulus rivaling that of the stiffest material known, diamond, while
maintaining a remarkable resistance to fracture. We have used atomic-force
microscopy (AFM) to manipulate the nanotubes through a series of
configuration that reveal buckling behavior and high-strain resilience.
Nanotubes also serve as test objects for nanometer-scale contact
mechanics. We have found that nanotubes will roll under certain
conditions. This has been determined through changes in the images and
through the acquisition of lateral force during manipulation. The lateral
force data show periodic stick-slip behavior with a periodicity matching
the perimeter of the nanotube.