Droplets suspended in mid-air with acoustic levitation instead of test tubes: a revolution for chemists?

Chemical laboratories may in the future abandon the classical test tubes to use drops of liquid suspended in mid-air by the method of acoustic levitation.

This is the project that Jack Beauchamp, a researcher at the California Institute of Technology, is working on, according to which inside the drop suspended in mid-air it is possible to trigger the chemical reactions that are currently confined in the tubes. Acoustic levitation is possible by exploiting the energy emitted by small, very powerful speakers that operate at a frequency imperceptible to the human ear.

In a new study, published in Angewandte Chemie International Edition, Beauchamp and colleagues describe the technique they are developing, research that represents, according to the scientist himself, “the first successful use of acoustic levitation as a reactor “without walls” in a detailed study of chemical reactions.”

They have already experimented with the use of these droplets with an anti-cancer drug. They made the latter react with lipids, biomolecules at the base of the cell membrane structure. Using the mass spectrometer, they “smelled” the chemical signature emitted by the droplet when the drug reacted with the lipid.

During the experiment, they used a drop of water one millimeter in diameter suspended in mid-air and illuminated by red laser light.

“As far as I know, we are the only people who do serious chemistry in this way, examining the kinetics and the mechanism of the reactions involved,” Beauchamp himself says.