Nanoscale measuring and imaging systems suffer from the
problem analyzed here. The atomic-force microscope and the scanningtunneling
microscope both rely on a probe, supported on a force loop, typically
with a piezo-electric actuator and electronics to sense the proximity of
the probe to the test surface. Closer to home, the mechanism of a video
recorder and that of a hard-disk drive qualify as precision instruments; both
have a sensor (the read head) attached, with associated electronics, to a
force loop. The materials identified in this case study are the best choice
for force loop.