60 SERVO 07/08.2018
Researchers have now devised a magnetic control system to make tiny DNA-based robots move on
demand — and much faster than recently possible.
In the journal, Nature Communications, Carlos
Castro and Ratnasingham Sooryakumar and colleagues
from Ohio State University report that the control
system reduced the response time of prototype nano-robot components from several minutes to less than a
Not only does the discovery represent a
significant improvement in speed, this work and
another recent study herald this first direct, real time
control of DNA-based molecular machines.
The discovery could one day enable nano-robots to manufacture objects such as drug-delivery devices as quickly and reliably as their full-size counterparts. Previously, researchers could
only move DNA indirectly, by either inducing chemical reactions to coax it to move certain ways
or introducing molecules that reconfigure the DNA by binding with it. Those processes take time.
"Imagine telling a robot in a factory to do something and having to wait five minutes for it to
perform a single step of a task. That was the case with earlier methods for controlling DNA nano-machines," said Castro, associate professor of mechanical and aerospace engineering.
"Real time manipulation methods like our magnetic approach enable the possibility for
scientists to interact with DNA nano-devices and, in turn, interact with molecules and molecular
systems that could be coupled to those nano-devices in real time with direct visual feedback."
In previous work, Castro's team used a technique called “DNA origami” to fold individual
strands of DNA to form simple microscopic tools like rotors and hinges. They even built a "Trojan
horse" out of DNA for delivering drugs to cancer cells.
Power is a fundamental problem for robots of any size. Any type that moves is constrained in
one way or another by its power supply —
whether that be relying on carrying around heavy
batteries, combustion engines, fuel cells, or
anything else. It can be particularly tricky to
manage power as robots get smaller, since it’s
much more straightforward to scale power up
rather than down.
For really tiny robots (with masses in the
hundreds of milligrams range) — especially those
that demand a lot of power — there haven’t been
any really good solutions. Typically, small insect
robots often have to depend on tethers for
power, which isn’t ideal for making them practical
in the long term.
At the recent IEEE International Conference on Robotics and Automation held in Brisbane,
Australia, roboticists from the University of Washington, in Seattle, presented RoboFly: a laser-powered insect-sized flapping wing robot that performs untethered flight through the use of
RoboFly’s design is based on the RoboBee flapping-wing microrobot from Harvard’s
MicroRobotics Lab; it’s about the size of a bumblebee, and weighs just 190 milligrams (a bit more
than a toothpick). It’s powered by an infrared laser aimed at a tiny little photovoltaic cell, which
can harvest the 250 m W required to get the robot airborne.
Photo: University of