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riding the waves
Professor Marlin Mickle and the Invention of
Radio Frequency Identification Tagging

Marlin Mickle has been working with radio waves since he was a boy. "My parents were very good with me when I was young,” he said during a visit to his office. “I had my own toolbox when I was just a little kid. I got my first typewriter when I was five. So I was used to experimenting and making things. Radio just took it to another level. I was 11 or 12 when I got a crystal radio. I didn't understand all the pieces at that time, but I knew enough to make it work. I was fascinated by the crystal radio which had no battery and no wires and did not have to be connected to something, and I wanted to find out how it worked.” And find out he did.

Lured by the GI Bill, after high school he joined the Air Force where he served as an airborne radar technician on the first RC131 AWACS aircraft. Following the Air Force, he enrolled at the University of Pittsburgh in 1958, joined the faculty in 1962 and graduated in 1967 with a Ph.D. in electrical engineering. A faculty member ever since, today in addition to filling the Nikolas A. DeCecco Chair in Electrical Engineering, he holds appointments in the departments of electrical engineering, computer engineering, telecommunications and industrial engineering.

Although he is most famous for his pioneering work in the development of radio frequency identification (RFID) tags, the work that led him to that technology, called energy harvesting, has resurfaced as a focus of his research.

“We got into the RFID business around 1998 because of the energy harvesting we were doing. We were trying to power sensors. We wanted to be able to put a sensor in places where batteries weren't practical or wires couldn’t be run. While we were doing that we had success. The Department of Defense wanted to get involved in RFID but every time a manufacturer or vendor brought something in it worked differently than the previous one. So they needed someone to come up with a set of tests and criteria by which you could evaluate them. So a colleague in industrial engineering and I made a proposal and we won the contract.”

Although RFID has ascended to a position of technological prominence and commercial success, Professor Mickle gives no hint that his days as an innovator are over. Today, he is back to harvesting radio waves from the air and converting them into electricity to power devices wirelessly. His inventions have been licensed to a half dozen companies for applications ranging from wireless Christmas trees to wireless chargers for small handheld devices. He has experimented with a wireless power supply for a new therapy for Parkinson’s disease called deep brain stimulation (DBS) in which a subcutaneous power storage device is wirelessly recharged from a patient’s headboard while he or she sleeps.

True to his vocation as a teacher, when I asked him to give a tutorial on his work for the electromagnetically challenged, he responded with patience and clarity.

“This is not a new concept,” he began. “It goes back more than a century to Tesla, who wanted to transmit electrical energy through the air instead of using wires. Most of what we do has to do with antennas. If it's a conductor, it's an antenna. With conductive polymers, the whole wall becomes an antenna. The first thing that happens when a wave impinges on an antenna is it causes a current to flow. And anytime you have any electrons flowing in a conductor, you're generating waves. And at certain frequencies, they will radiate into space. The trick of how you get that energy out is where we come into play.”

Toward the end of our visit, the conversation turned toward the future of radio frequency technology. “With a crystal set you think of an antenna from which you direct the energy into the device. So you think of an antenna as a harvesting device. I believe that we can come up with a metamaterial that will be conductive in a way that we don't fully understand right now. We are thinking about effectively collecting a pool of energy – a battery in space. It's not ready to be used. But it will be someday."

This story first appeared in Tom Imerito’s TEQ column, Innovation Chronicles. You can read it on the Pittsburgh Technology Council’s website.

©Copyright 2007 Thomas P. Imerito/ dba Science Communications

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