Scientists make droplets move on their own

September 29, 2014

Droplets are simple spheres of fluid, not normally considered capable of doing anything on their own. But now researchers have made droplets of alcohol move through water. In the future, such moving droplets may deliver medicines, etc. To be able to move on your own – to be self-moving – is a feature normally seen in living organisms. But also non-living entities can be self-moving, report researchers from University of Southern Denmark and Institute of Chemical Technology in Prague, Czech Republic.

The researchers have made alcohol move in a life-like way, and this could lead to interesting new technology, they say.

"The system itself is very simple but yet it displays sophisticated behavior", explains principal investigator Martin Hanczyc, who was at Center for Fundamental Living Technology (FLINT), University of Southern Denmark, when the research was done.

Martin Hanczyc is now at Centre for Integrative Biology, University of Trento in Italy. The study's first author is Jitka Cejkova, also formerly with University of Southern Denmark, now assistant professor at the Chemical Robotics Laboratory of Professor Frantisek Stepanek at the Institute of Chemical Technology in Prague.

Hanczyc and his colleagues from Prague have shown that small droplets of alcohol in water can move through complex mazes. The droplets can be led to certain targets, and therefore they may be used as a technology to physically move chemistry to a place where it is desired.

"For example, the droplet can act either as a lubricant, targeting an area that needs lubrication. Or the droplet can act as a carrier for chemistry that can find a target destination and release its content, such as flavoring, medicine etc.", Martin Hanczyc explains.

The droplets start to move when they sense salt in their environment.

This video shows an alcohol droplet (pink) find its way through a maze, guided by a salt concentration (yellow).

"Salt is the stimulus that makes them move. They move because the salt gradient provides a different energy landscape. It is like taking a ball that is laying still on a flat surface and then suddenly make the surface hilly. The ball will roll to the lowest accessible point. That is what the droplet is doing. Without a salt gradient every direction in which a droplet might move looks the same (flat). But with a salt gradient coming from one direction the droplet can move energetically downhill into the salt gradient. And stronger salt concentrations will attract the droplet more", says Martin Hanczyc.

The system is sustainable in that the same droplet can migrate towards salts at different positions added sequentially. In addition the droplet can distinguish between salt sources of different concentration. The process can also be controlled by external temperature stimulus, and when the droplet arrives at the source it can physically fuse with it and react with it.

Martin Hanczyc has previously reported that display a life-like moving behavior and may be a simple chemical predecessor to biological life.

Explore further: Water droplets prefer the soft touch

More information: Dynamics of chemotactic droplets in salt concentration gradients, Jitka Cejkova, Matej Novak, Frantisek Stepanek, and Martin Hanczyc. Langmuir, Sept 12 2014.

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not rated yet Sep 29, 2014
This is very cool information and 'hopefully' it will be used for good in the future.
"Scientists make droplets move on their own"
"The process can also be controlled by external temperature stimulus"
"Martin Hanczyc has previously reported that oil droplets display a life-like moving behavior"
I think the key phrase is "controlled by an external stimulus"
The truth is; water on it's own will remain water
Take for instance, sterile water in a sterile sealed jar will not move, change, evaporate until an 'outside force' is exerted; e.g. the jar is opened and evaporation takes place, the jar is broken and water pours out to the floor, or,
If hit with an electrical charge. If hit with a baseball bat. If salt is added it becomes salt water!
If nothing is changed and the sterile water stays inside the sealed jar, it remains a jar of water, unchanged.
If you add alcohol (under the right condition; such as to your gas, it will combine with the water and burn it up as fuel.
Good Luck!
not rated yet Sep 30, 2014
"On its own" is misleading.... there is no sentience... "by intelligent design" would be more accurate... or... "Look ma - no hands!". Manually relocating water has been occurring for as long as people have been around. Remotely moving water on a nano-scale is a miniaturized version.
Sep 30, 2014
This comment has been removed by a moderator.
not rated yet Sep 30, 2014
Even speeded up as the video is, it's sort of interesting to note how quickly the dot starts to move (i.e. how quickly salt ions cover the distance).

On the other hand blood flow in the body might be too turbulent to use this for any kind of targetted medication. But I'm sure this could have a wide variety of uses (maybe added to dispersants in case of an oil spill so that the chemicals are only released once they contact the oil)
not rated yet Sep 30, 2014
Is this a means in which tumors are formed?

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