Two associate professors of chemistry have changed a research problem into a research asset.
James N. Demas of the University of Virginia and J. R. Bacon of Western Carolina University have invented a luminescent oxygen sensor whose potential applications include making quick measurements of the level of oxygen in polluted water or air samples, and monitoring oxygen-delivery equipment in hospitals or homes.
The problem "is that oxygen is an interferent in most of the fundamental studies" that are performed in the field of chemistry, Demas said. "What we did is turn that around and say 'Why make oxygen an interference? Why not turn it around and make it a tool?' Although we weren't the first ones to think of it, I think our systems are unique, springing from laboratory curiosity to a potentially viable commercial instrument."
Demas' background is in luminescence spectroscopy, while Bacon is an analytical chemist. Although they teach and conduct research at different institutions, Demas and Bacon ended up working together because Bacon wanted to conduct some research while he was teaching at the University of Virginia during a sabbatical in 1981-82.
According to Demas, the potential market for the oxygen sensors is almost unlimited. Biomedical applications make up a large part of this market, including the monitoring mentioned earlier. There also are environmental applications, such as using the sensor in programs in which state laboratory employes measure the amount of oxygen in organic material in waste water to see how damaging the effluent material will be to the environment, Demas said.
Hundreds of such tests are conducted in Virginia each month, for example. "We believe we could automate the entire operation and put it into the corner of the laboratory saving time, space and manpower," Demas said. He projected a minimum monetary savings of more than 20 percent by using the new sensors. Demas also predicted that use of the luminescent oxygen sensor might permit 50-day tests rather than the five-day tests conducted now. The longer tests would let officials monitor the effect of slower chemical reactions.
The instruments also could be used in space capsules, mines and areas where hazardous materials are produced or handled. The sensor uses a small strip of a luminescent platinum metal compound covered by a gas-permeable membrane. When light stimulates this metal and no oxygen is present, the metal glows brightly; the greater the concentration of oxygen present, the lower the degree of luminescence. The membrane allows oxygen to work its effects when the sensor is placed in liquids while preventing it from reacting to dissolved contaminants. Such reactions previously prevented use of oxygen-sensitive luminescent materials for monitoring.
The invention represents a step forward, Demas said, because current methods for detecting oxygen are too slow, don't lend themselves to automation, consume oxygen or can't be adapted for a wide range of uses.
He said production models of the sensor might consist of a strip of the membrane-covered material, a light source, a photo detector to calculate the amount of luminescence, and read-out electronics. Another configuration could eliminate the read-out electronics, leaving the user to measure the degree of luminescence by comparing the actual strip against control strips.
The entire package, with the exception of the read-out electronics, could fit in a cylinder an inch or two in diameter and several inches long, Dumas said. It also could be made much smaller for a catheter probe, he added. And the metal sensors could measure oxygen in cell samples examined under a microscope if the sensors were first encapsulated in microscopic beads.
Commercial applications are under development through a license with the University of Virginia Alumni Patents Foundation, which has applied for a patent on the luminescent oxygen detector. Demas said he was not at liberty to name the company involved.
Once the sensor is marketed, 15 percent of the proceeds will go to Demas and Bacon, in accordance with university policies, and other amounts will go to Demas' department.
Demas estimated that he spends an average of about 40 percent of a "normal" 50- to 70-hour work week on research during the school year, and conducts more research during the summer. He called this pattern typical of colleagues who are "research-active." This year, Demas will teach courses in electronics computer interfacing.
Demas was born in the District, but grew up in Albuquerque. He has been at the University of Virginia since 1971.