Nanomachines are largely in the researchand-development
phase[1], but some primitive molecular machines have been tested. An example is
a sensor having a switch approximately 1.5 nanometers across, capable of counting specific
molecules in a chemical sample. The first useful
applications of nanomachines, if such are ever built,
might be in medical technology, where they might
be used to identify cancer cells and destroy them.
Another potential application is the detection of
toxic chemicals, and the measurement of their
concentrations, in the environment. Recently, Rice
University has demonstrated a single-molecule car
which is developed by a chemical process and
includes buckyballs for wheels. It is actuated by
controlling the environmental temperature and by
positioning a scanning tunneling microscope tip.