While many chemists are working to reduce the elements of a chemistry lab to a single chip replete with miniature pumps, channels, and valves, others are striving for a simpler route to miniaturization. Rather than shuttling liquids through complex microfluidic plumbing, some scientists have imagined doing all their chemistry by rolling drops of liquid from one chip location to the next. Now, a group of chemists has devised a strategy to fulfill this vision using nothing more than a magnet and a bit of dust.
It’s not ordinary dust, but smart dust: microparticles of porous silicon that resemble miniature shards of glass. Developed by Michael Sailor of the University of California, San Diego (UCSD), the particles can be made to reflect different wavelengths of light according to the specific chemical or biological molecule to which they’re bound (SN: 6/7/03, p. 362: Available to subscribers at Danger Detection).