Self-propelled nano- or microscale |
Scientists
have developed a new kind of tiny motor—which they term a
“microrocket”—that can propel itself through acidic environments, such
as the human stomach, without any external energy source, opening the
way to a variety of medical and industrial applications. Their report in
the Journal of the American Chemical Society
describes the microrockets traveling at virtual warp speed for such
devices. A human moving at the same speed would have to run at a clip of
400 miles per hour.
Joseph
Wang and colleagues at the University of California, San Diego explain that self-propelled nano- or microscale
motors could have applications in targeted drug delivery or imaging in
humans or as a way to monitor industrial applications, such as
semiconductor processing. However, some versions of these small-scale
motors are not self-propelled and require the addition of a fuel
(commonly hydrogen peroxide). Other versions cannot withstand extreme
environments such as the stomach, which is very acidic. That’s why the
researchers developed a new, tubular microrocket that can move itself
without added fuels in very acidic conditions.
They
tested the new microrocket in various acids and in acidified human
blood serum. In such environments, a microrocket spontaneously produces
bubbles of hydrogen gas, which propels it like the gases spewing out of a
rocket’s motor nozzle. The microrocket is ultrafast—it can move farther
than 100 times its 0.0004-inch length in just one second. In contrast
to current devices of this kind, the microrocket’s interior is lined
with zinc, which is more biocompatible and “greener” than other
materials and leads to the generation of the hydrogen bubbles. Wang’s
team also developed a version with a magnetic layer, which enabled them
to guide the microrockets toward cargo for pick-up, transport and
release.
Hydrogen-Bubble-Propelled Zinc-Based Microrockets in Strongly Acidic Media
