Genetic engineers have, however, tinkered with the phage, and have arranged for it to produce a fluorescent protein called luciferase when it infects a bacterium.
Just one square inch, the chip contains 2, 056 microvalves that can selectively mix reagents together (in this case to test for the activity of a particular enzyme in a bacterium) in 256 reaction chambers, each one holding less than one-billionth of a liter of fluorescent dye.