Biology's equivalent of an office copier is a PCR machine. PCR, short for polymerase chain reaction, is now a staple in crime-scene forensics, heredity tests, and organism hijacking. It's a mind-boggling feat. Among billions of base pairs that make up DNA's genetic code, PCR finds exact sequences and, in a couple of hours, makes billions of copies—enough to decode or splice together useful combinations of genes. Professional machines cost about $10,000 dollars each, but Russell Durrett has devised one from PVC pipes, a 150-watt lightbulb, a computer fan, a cheap microcontroller, and a few reagents he ordered online.
Stack five pieces of PVC piping to form a silo [right] that holds vials of DNA, heats them with a lightbulb, and cools them with a computer fan.
TOP Drill a dozen…