QUESTION: What the hell do they eat?
DOE/Lawrence Berkeley National Laboratory
When
you think of a robot, images of R2-D2 or C-3PO might come to mind. But robots
can serve up more than just entertainment on the big screen. In a lab, for
example, robotic systems can improve safety and efficiency by performing
repetitive tasks and handling harsh chemicals.
But
before a robot can get to work, it needs energy -- typically from electricity
or a battery. Yet even the most sophisticated robot can run out of juice. For
many years, scientists have wanted to make a robot that can work autonomously
and continuously, without electrical input.
Now,
as reported last week in the journal Nature Chemistry, scientists
at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley
Lab) and the University of Massachusetts Amherst have demonstrated just that --
through "water-walking" liquid robots that, like tiny submarines,
dive below water to retrieve precious chemicals, and then surface to deliver
chemicals "ashore" again and again.
The
technology is the first self-powered, aqueous robot that runs continuously
without electricity. It has potential as an automated chemical synthesis or
drug delivery system for pharmaceuticals.
"We have broken a barrier in designing a liquid robotic system that can operate autonomously by using chemistry to control an object's buoyancy," said senior author Tom Russell, a visiting faculty scientist and professor of polymer science and engineering from the University of Massachusetts Amherst who leads the Adaptive Interfacial Assemblies Towards Structuring Liquids program in Berkeley Lab's Materials Sciences Division.
Russell
said that the technology significantly advances a family of robotic devices
called "liquibots." In previous studies, other researchers
demonstrated liquibots that autonomously perform a task, but just once; and
some liquibots can perform a task continuously, but need electricity to keep on
running. In contrast, "we don't have to provide electrical energy because
our liquibots get their power or 'food' chemically from the surrounding
media," Russell explained.
Through
a series of experiments in Berkeley Lab's Materials Sciences Division, Russell
and first author Ganhua Xie, a former postdoctoral researcher at Berkeley Lab who
is now a professor at Hunan University in China, learned that
"feeding" the liquibots salt makes the liquibots heavier or denser
than the liquid solution surrounding them.
Additional
experiments by co-investigators Paul Ashby and Brett Helms at Berkeley Lab's
Molecular Foundry revealed how the liquibots transport chemicals back and
forth.
Because
they are denser than the solution, the liquibots -- which look like little open
sacks, and are just 2 millimeters in diameter -- cluster in the middle of the solution
where they fill up with select chemicals. This triggers a reaction that
generates oxygen bubbles, which like little balloons lift the liquibot up to
the surface.
Another
reaction pulls the liquibots to the rim of a container, where they
"land" and offload their cargo.
The
liquibots go back and forth, like the pendulum of a clock, and can run
continuously as long as there is "food" in the system.
Depending
on their formulation, an array of liquibots could carry out different tasks
simultaneously. For example, some liquibots could detect different types of gas
in the environment, while others react to specific types of chemicals. The
technology may also enable autonomous, continuous robotic systems that screen
small chemical samples for clinical applications, or drug discovery and drug
synthesis applications.
Russell
and Xie next plan to investigate how to scale up the technology for larger
systems, and explore how it would work on solid surfaces.
The
Molecular Foundry is a nanoscience user facility at Berkeley Lab.
This work was supported by the DOE Office of Science. Additional support was provided by the U.S. Army Research Office.
