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100 Years of Electronics Made Possible by Vacuum Tube

One hundred years ago this month, the electronic age was born with a British patent application. VOA's Mike O'Sullivan looks back on the contribution of John Ambrose Fleming, developer of the vacuum tube. His pioneering work was recalled at a recent scientific conference in Los Angeles.

It was November, 1904, when Mr. Fleming filed his patent application for a device he called an "oscillation valve." It was based on Thomas Edison's incandescent lamp, which had a filament in a glass bulb that had been evacuated of air. The filament glowed when electricity passed through it.

Physicist Fred Dylla of the Jefferson Lab in Newport News, Virginia, says Mr. Fleming added a metal plate with a positive electric charge, transforming the light bulb into a device that regulates currents.

"What we call in the U.S. the vacuum tube. And the vacuum tube became the first component of what was to become the electronics industry, the basis for radio and radio communications, and then television. And this was the workhorse component of that industry until it was supplanted by the transistor," explained Mr. Dylla.

The transistor was developed in 1947, followed by the integrated circuit or chip, tiny clusters of transistors that form the basis for most modern electronics.

Vacuum tubes still have a place in some electrical devices, such as microwave ovens. And the cathode-ray tube still provides the viewing screen for many computers and televisions. But most electronic devices, from digital watches to computers, operate by using silicon chips.

An organization once called the American Vacuum Society, now simply known as AVS, brings together thousands of engineers and scientists to discuss developments in electronics. Mr. Dylla says there are electrical and mechanical engineers and physicists.

"And even biophysicists and biochemists, because we are now learning to graft very simple biological organic molecules onto an inorganic semiconductor chip to make sensors that will have some use for us in medicine," he added.

A new industry has grown up to support the companies that fabricate components, which are made in clean, often air-free environments. Allen Demetrius is executive vice president of the Kurt Lesker Company, which makes vacuum devices.

"When you're talking about integrated circuits, you're talking about depositing materials at the atomic or molecular level," he explained. "And when you get down into that type of process, you need a pristine environment, where any contamination would be detrimental to those processes. So you create an environment that is essentially void of all contamination."

Development scientist Mike Skegg of Omicron Nanotechnolgies says the new microelectronics industry brings its own set of problems. His company makes instruments that locate flaws on the surface of chips and other miniature devices.

"The smaller the electronics get, the more perfect it's all got to be," he noted.

Physicist Fred Dylla says the early 20th century inventor John Ambrose Fleming might be overwhelmed by the range of instruments and the pace of change today in the industry he helped create. There is a new generation of electronic chips every year and a half. Consumer computers double in speed in about the same time span. And chips are found in nearly every household appliance. But Mr. Dylla says the British engineer would have recognized the principles of modern electronics, which are the same as those that led to his "oscillation valve" a century ago.