If the fingerprint-smudged glass plates on biometric devices skeeve you out, Purdue University researchers have some good news for you: The devices aren’t any germier than typical doorknobs.

Christine Blomeke, a researcher and doctoral student in Purdue's Biometric Standards, Performance and Assurance Laboratory, says the lab performed a study on this issue in light of concerns by those involved in fingerprint and hand-geometry studies at the lab. The study involved testing for two kinds of bacteria, staphylococcus aureus and E.coli.

"When you look at these devices, finger moisture, dirt and oils cause the surface to appear to be dirty," Blomeke said in a statement. "In a study we did on this last year, more than a quarter of the participants indicated that they thought the devices were somewhat unsanitary.

"Since the use of biometric devices is rapidly expanding in public spaces, such as airports, stores and banks around the world, we felt it was important to examine whether touching these surfaces would subject users to more germs than they would be exposed to by touching objects such as pens, doorknobs and elevator buttons."

Study results were presented this week at the Institute of Electrical and Electronics Engineers International Carnahan Conference on Security Technology in Ottawa, Ontario.

Tests involved finding out how well bacteria survived on biometric devices and how well it transferred. Researchers found that E.coli outlasted staph bacteria on biometric devices but that neither lasted long.

"What we can take away from this is that no matter what kind of a surface it is, if it is contaminated, the more it is touched, the cleaner the surface becomes," Blomeke said.

Of course, the biometric device vs. doorknob debate can be confusing. After all, one company has introduced a biometric doorknob.