Levitating droplets allow scientists to perform 'touchless' chemical
reactions

Date:
June 24, 2020
Source:
American Chemical Society
Summary:
Levitation has long been a staple of magic tricks and movies. But
in the lab, it's no trick. Scientists can levitate droplets of
liquid, though mixing them and observing the reactions has been
challenging. The pay- off, however, could be big as it would allow
researchers to conduct contact-free experiments without containers
or handling that might affect the outcome. Now researchers have
developed a method to do just that.



FULL STORY ========================================================================== Levitation has long been a staple of magic tricks and movies. But in
the lab, it's no trick. Scientists can levitate droplets of liquid,
though mixing them and observing the reactions has been challenging. The pay-off, however, could be big as it would allow researchers to conduct contact-free experiments without containers or handling that might
affect the outcome. Now, a team reporting in ACS' Analytical Chemistry
has developed a method to do just that.


========================================================================== Scientists have made devices to levitate small objects, but most methods require the object to have certain physical properties, such as electric
charge or magnetism. In contrast, acoustic levitation, which uses sound
waves to suspend an object in a gas, doesn't rely on such properties. Yet existing devices for acoustic levitation and mixing of single particles
or droplets are complex, and it is difficult to obtain measurements from
them as a chemical reaction is happening. Stephen Brotton and Ralf Kaiser wanted to develop a versatile technique for the contactless control of
two chemically distinct droplets, with a set of probes to follow the
reaction as the droplets merge.

The team made an acoustic levitator and suspended two droplets in it,
one above the other. Then, they made the upper droplet oscillate by
varying the amplitude of the sound wave. The oscillating upper droplet
merged with the lower droplet, and the resulting chemical reaction was monitored with infrared, Raman and ultraviolet-visible spectroscopies. The researchers tested the technique by combining different droplets. In one experiment, for example, they merged an ionic liquid with nitric acid,
causing a tiny explosion. The new levitation method could help scientists
study many different types of chemical reactions in areas such as material sciences, medicinal chemistry and planetary science, the researchers say.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Stephen J. Brotton, Ralf I. Kaiser. Controlled Chemistry via
Contactless
Manipulation and Merging of Droplets in an Acoustic
Levitator. Analytical Chemistry, 2020; 92 (12): 8371 DOI:
10.1021/acs.analchem.0c00929 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200624120438.htm

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