Number 367 (Story #1), April 16, 1998 by Phillip F. Schewe and Ben Stein MICROFLUIDICS: MIXING NANOLITERS IN MICROSECONDS. Biophysicists would love to assemble a movie of the process by which the proteins essential for life assume their unique 3-dimensional shapes. One way to do this is to control the "denaturant" in the solvent surrounding the proteins, thus encouraging or discouraging protein folding. The trouble is to change the solvent conditions quickly enough to observe the sub- millisecond folding at work. This demands a fluid mixer of exceptional speed. Toward this end Princeton researchers (contact Jim Knight, jknight@princeton.edu) have microfabricated a tiny mixing vessel in which a submerged fluid jet (pinched down to a waist as small as tens of nm) is used to achieve fluid mixing times of less than ten microseconds. The mixed sample is delivered in a controlled manner (laminar flow rather than the turbulent flow in some other mixing vessels) at flow rates of nanoliters per second. (At this rate a shot of espresso would take a year to deliver.) The Princeton mixer, frugal with expensive samples and compact enough to sit on a silicon chip, may open up new ways to perform parallel, automated chemical testing. Microfluidics may be to chemistry what microelectronics is to electricity. (Knight et al., upcoming article in Physical Review Letters.)