Tech Briefs Magazine - August 2021 - MD-18

NanoGear Molecular Gear
Oscillatory and rotational motions of different parts are combined to pave the way to developing
super-miniaturized mechanical devices.
University of Bologna, Italy
Researchers designed, built,
and tested NanoGear, a device
consisting of molecular components
interlocked and designed
to function like a gear. Since molecules
are nanometer objects (1
nanometer = 1 millionth of a millimeter),
it is an extremely small
device.
The NanoGear molecule be -
longs to the class of rotaxanes
and consists of a ring that can
slide along an axis in the center
of which a rotor is installed. The
ring is free to slide along the
axis for its entire length but it
cannot escape because two stoppers
positioned at the ends of
the axis prevent it from slipping
off. The rotor is free to rotate
around its own axis and has two different
blades to facilitate observation of
the movement.
The rotor is bonded directly to the
shaft with an actual (covalent) chemical
bond, while the ring is mechanically
locked around the shaft by the presence
of the stoppers. Both the translation
of the ring and the rotation of the
blades are random oscillations determined
by the thermal energy of the
molecule; the gear is not coupled to
any motor and operates " in neutral. "
To observe the movements and measRing
Rotor
Axle
Stopper
Stopper
The
NanoGear molecule consists of a ring that can slide along an axle that bears a rotor installed in its center. At 65 °C,
the ring shuttles from one end of the axle to the other about seven times per minute, passing over the rotor; in the same
amount of time, the rotor completes about 260 rotations. (Credit: Center for Light Activated Nanostructures (Clan)/
University of Bologna)
ure their velocities, refined nuclear
magnetic resonance (NMR) techniques
were used.
At 65 °C, the ring oscillates linearly
from one end of the axis to the other
about seven times per minute, passing
over the rotor, while in the same period
of time, the latter performs about
260 rotations. Therefore, the two
motions are not synchronized but mu -
tually influence each other, as demonstrated
by experiments carried out on
molecules similar to NanoGear but
without a rotor or ring.
Soft Mate Lifting Device
This below-the-hook device enables gentle crane placement to decrease the risk of property
damage.
Marshall Space Flight Center, Alabama
Cranes for lifting and lowering heavy
objects are an important and sometimes
essential tool in modern industries
such as construction, transportation,
and manufacturing. NASA uses
overhead and mobile cranes for assembly
of load lines employed in full-scale
18
Cov
ToC
testing of its Space Launch System
(SLS), a super-heavy-lift launch vehicle
for deep space human space exploration.
Structural testing of the SLS
requires precision placement of heavy
objects with soft contact during mating
connections, which proved to be problematic
with the relatively coarse control
available with motor-driven overhead
cranes and the existing rigging
devices.
In response, NASA Marshall designed
the Soft Mate lifting device to incorporate
an adjustable pneumatic soft spring
Motion Design, August 2021
Another significant and unexpected
result is the effect of the medium in
which the molecule is located. By
changing the solvent, one of the two
movements is slowed down while the
other is accelerated. This kind of " specific
lubrication " constitutes one of the
unconventional properties of nanodevices
that could lead to radical technological
innovations.
For more information, contact Monica
Lacoppola at monica.lacoppola@unibo.it;
+39 051 20 9 8547.
http://www.abpi.net/ntbpdfclicks/l.php?202108MDNAV
Tech Briefs Magazine - August 2021

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