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Self-Cleaning Sensors
Michelle M. Lang -- Design News, June 27, 2004
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Who says sensors are easily contaminated? Craig Grimes has found a material that enables hydrogen sensors to rid themselves of impurities.
PRESENT POSITION: Associate Professor, electrical engineering/materials science, Pennsylvania State University
DEGREES: B.S., M.S. in physics, Penn State; Ph.D. in electrical engineering, University of Texas, Austin
HOW YOU DESCRIBE YOUR RESEARCH WHEN AT COCKTAIL PARTIES: There's a truth that the more sensitive a sensor is, the quicker it gets dirty. But photochemical properties of these sensors used to detect hydrogen can degrade any contaminants that fall onto them. The premise is that you can stick a sensor in the real world and it will continue to work.
WHAT MAKES THESE HYDROGEN SENSORS "SELF-CLEANING"? They are made of titanium nanotubes, lined up beside each other. Since the photocatalytic properties are so large with this nanotube geometry, the tube-to-tube contact creates amazing absorption characteristics that go across the spectrum from UV to visible light; the material absorbs the light, generating an electron-hole pair, which reduces contaminants.
ARE THERE ANY CONTAMINANTS THE SENSORS DON'T WORK WITH? Yes, certain types of salts will degrade the photochemical properties, so they don't work in the ocean or with WD-40.
WHAT'S THE BENEFIT OF SELF-CLEANING HYDROGEN SENSORS? First, from a cost perspective, self-cleaning sensors mean that you don't have to replace the sensors as often, if at all. Second, burning hydrogen results in emission of only water, which is perfectly clean. Once we have a useful supply of hydrogen, we can begin to wean ourselves off of our oil dependence.
WHEN WILL THEY BE COMMERCIALLY AVAILABLE? The self-cleaning hydrogen sensors have been licensed to SentechBiomed (www.sentechbiomed.com); we're now focused on the photochemical properties.
To view images of the titanium nanotubes, go to http://rbi.ims.ca/3851-533. Contact Grimes at cgrimes@engr.psu.edu.
