Getting pharmaceuticals from solution into an amorphous state, however, is no easy task. If the solution evaporates while it is in contact with part of a vessel, it is far more likely to solidify in its crystalline form. "It's almost as if these substances want to find a way to become crystalline," Benmore said.
In order to avoid this problem, Benmore needed to find a way to evaporate a solution without it touching anything. Because liquids conform to the shape of their containers, this was a nearly impossible requirement -- so difficult, in fact, that Benmore had to turn to an acoustic levitator, a piece of equipment originally developed for NASA to simulate microgravity conditions.
The acoustic levitator uses two small speakers to generate sound waves at frequencies slightly above the audible range -- roughly 22 kilohertz. When the top and bottom speakers are precisely aligned, they create two sets of sound waves that perfectly interfere with each other, setting up a phenomenon known as a standing wave.
At certain points along a standing wave, known as nodes, there is no net transfer of energy at all. Because the acoustic pressure from the sound waves is sufficient to cancel the effect of gravity, light objects are able to levitate when placed at the nodes.