Cleanroom: The Machine That Manufactures Air

The story of how one engineer purified air, and made our age of advanced electronics possible.

Willis Whitfield with a mobile cleanroom in the 1960s (NNSANews/Flickr)

You can scrub all you want but you'll never get your room *ultra* clean. Why? Because of air -- filthy, filthy air.

In so called "clean air" in rural areas, an average cubic foot of air contains some two to three million microscopic particles -- germs and dust and the like -- and in cities or near dense manufacturing zones, that number can be much, much higher, in the tens of millions. Those particles seem small to us, but they can do a lot of damage. As Gilbert V. Herrera of Sandia National Laboratories put it, "Relative to these electronics, the particles are just massive boulders that would short out all of your electronics and make them not work." But how to get rid of them?

Last month the man who figured that out passed away in Albuquerque, New Mexico, the New York Times reports, 50 years after inventing a room -- an "ultra-clean room" -- whose basic mechanisms have made our modern electronics age possible. Willis Whitfield's solution to the particle problem was so simple that people thought he was full of it. Whitfield himself could hardly believe it: "We turned on the particle counter and it just stopped counting. We thought there was something wrong with it," he told a group at his old lab in 2005.

A figure from Willis Whitfield's 1964 patent for an "Ultra Clean Room." Line 153 shows the presence of particles in the present invention, whereas lines 150, 151, and 152 shows rooms "heretofore known clean." "The sharp rise and drop indicated on line 153 at about 0900 was the result of cigarette smoke being blown into the room to check its effects." (Google Patent)

It worked by relying on one of the most basic forces there is: gravity. Whitfield's idea was to continuously circulate air in through the ceiling, down and out the floor, and then back up to the ceiling again, using gravity to pull particles down where they would be filtered out and sent into an exhaust system. The air in the room changed 10 times every minute, so fast that the cleanroom was "clean" almost immediately after being turned on. The patent, which Whitfield received in 1964, was shared freely by the government with manufacturers and hospitals (Sandia, where Whitfied worked, is part of the National Laboratories).

Whitfield's original room was quite small, though the design would work for spaces of much greater size, as long as you built filters to keep air moving at the right pace. Today, the New York Times reports, iPhones are built in massive cleanrooms in structures that are more than a million square feet.

For all the technological complexities of modern circuitry, one element seems, on its face, not to be technology at all: air, pure air. But Whitfield's cleanroom reveals the speciousness of that impression. Air this clean is something we manufacture -- an ingredient built of the resources we have around us, refined by Whitfield's machine and a small assist from gravity.

Whitfield with the statue honoring him at Sandia National Laboratories (NNSANews/Flickr)