Materials Research Science and Engineering Center
Amorphous Salt
The Microfluidic Nebulator

Table salt (NaCl) is always crystalline! But wait!! A Harvard MRSEC team reported, in the August 29, 2015 issue of Science, a microfluidic spray drier, the nebulator (a,b), that forms very small drops of fluid that are spray dried. David Weitz, Frans Spaepen, and Michael Brenner use the microfluidic spray drier to make nanoparticles of virtually all materials, including drugs and inorganic materials. Because the drops are so small, the particles dry very rapidly and are kinetically trapped in an amorphous state, providing a simple means to produce amorphous nanoparticles. The amorphous particles are much more soluble, making them valuable for drug delivery. They are also surprisingly stable because crystallization is kinetically delayed due to their small size. Even something as ubiquitously crystalline as table salt can be made amorphous; there are no lattice planes seen by TEM (c) until the electron beam heats the nanoparticle to crystallize it (d).

D.A. Weitz
DMR 14-20570