Jason Daley in Popular Science:
If you were to toast the most dazzling gadget in your home, you might compose an ode to your plasma TV, recite a limerick about your computer-controlled telescope, or maybe sing the praises of your video conferencing, nose-hair-trimming espresso maker. But the invention most deserving of your adoration, the contraption that will one day sit in the pantheon of great American machines alongside the telephone and the transistor radio, is something far more prosaic. It is the inkjet printer, and it is much more than a peripheral. Its core technology may seem simple—an array of nozzles that moves back and forth, depositing tiny droplets of ink on paper—but its breadth of uses has turned out to be nothing short of astonishing, so much so that the humble inkjet is driving innovation in disciplines from aerospace engineering to pharmacology.
How does a printer go from spitting out pictures of Uncle Bob to powering jet planes? The secret of the inkjet’s unheralded versatility lies in its print head—a silicon or composite plate a tenth of an inch wide studded with as many micro-nozzles as a manufacturer can cram onto it. The nozzles fill with ink, and either heat or an electric charge forces out uniform droplets [see “Inkjet 101,” below]. Refined over the past 20 years from heads with 12 nozzles to ones with more than 3,000, the inkjet is the first cheap, mass-produced machine to control minute pearls of fluids—it ultimately jump-started the field of microfluidics. This precise control of ever-smaller droplets (some now a small fraction the size of a pinpoint), coupled with faster printing speeds has opened up dozens of new and decidedly more glamorous applications: printing cellphones and human livers, delivering drugs more efficiently and without side effects, producing fuels without nasty by-products.