Acoustic levitation is pretty damn cool, and a useful scientific tool to boot. Researchers use the process to test various drugs and in which state — crystalline or soluble — they'd be most effective.
When taken to the molecular level, pharmaceuticals are either amorphous or crystalline. Amorphous drugs are more easily dissolved and have a higher bioavailability, which means the proportion or dose of the drug that is needed to achieve the desired effect is lower.
Researchers at the Argonne National Laboratory in Chicago are experimenting with the levitation technique in drug development because, as X-ray physicist and study leader Chris Benmore told WiredUK:
"One of the biggest challenges when it comes to drug development is in reducing the amount of the drug needed to attain the therapeutic benefit, whatever it is."
So the goal of the process is testing efficiency of drugs, and which form of the drug is most efficiently absorbed by the body. To find out, each version needs to be evaporated, but when most solutions are evaporated in a vessel they also turn into the crystalline form. So to get the most effective test of soluble drug solutions, the liquids need to be evaporated without touching anything. Thus, acoustic levitation.
As it turns out, NASA uses acoustic levitation to simulate microgravity, so Benmore simply adapted the technique for the pharmaceutical purpose of creating untouched samples that can be studied by the lab's high-energy X-ray beam as they evaporate.
The levitator itself uses two small speakers, perfectly aligned on top of each other. They generate sound waves around 22 kHz — which is just above the audible range — and because the speakers are aligned, they are created two sets of sound waves that perfectly interfere with one another, which is known as a standing wave.
At certain points along the standing wave there is no net transfer of energy. The acoustic pressure from the sound waves cancels out the effects of gravity that is what causes light objects like droplets to levitate, as you'll see in the video below.
Argonne's technique opens up an efficient way to test the best way for drugs to be delivered and ultimately create the amorphised versions — even if in small quantities. Argonne researchers are working to patent their technique and potentially open it up for commercialization.