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PRI's Environmental News Magazine

Smart Dust

Air Date: Week of September 26, 2003

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Doctor Michael Sailor talks with host Steve Curwood about his research on smart dust, tiny particles that can detect air and water pollution.

Transcript

CURWOOD: Computers continue to shrink. So do cell phones and cameras. Now, scientists are trying to shrink pollution detectors down to the size of a grain of sand. These teeny-tiny devices will be able to recognize contamination in the air and water and alert humans to any dangers. Doctor Michael Sailor heads up a University of California at San Diego research team that’s working on these devices. Their latest success: an experiment using this so-called “smart dust’ to pinpoint a droplet of oil in water.

SAILOR: What we did is we took the particles and we placed some chemistry on them so they would target, specifically target, an interface. The interface was a drop of oil in water. And the idea is we could just sprinkle these little particles. They look like glitter – they’re a little bit more complicated than just the glitter you would buy at the cosmetic store. And we sprinkle them into water, and then they’ll fly around through the liquid, and if there’s a drop of oil in there then the chemistry on the surface is set up so that these little particles will go stick to that surface. These little particles look like little mirrors, and when they hit that oil drop it looks just like a little mini-disco ball. And those mirrors will reflect light back to an observer, and so we can read the mirrors. And unlike the mirrors on a disco ball, these little mirrors change color when they know they’ve seen the oil. And so they hit that interface, they stick to it and they coat it, and then they report back to us that they’ve found the oil.

CURWOOD: What’s the advantage of this process?

SAILOR: The oil droplet is just sort of a model for a cell. And we’re trying to get these things to target things like cells, like cancer cells in the body, or maybe an E.coli, a bacterium in drinking water. And so by targeting these cells they can go find them, and tell us that they’ve found them. And we’d have a way of monitoring, say in the case of a cancer cell, monitoring the health of a patient. In the case of E.coli or bacteria in water we have a way of monitoring the quality of the water.

CURWOOD: I understand that some of your work involves sending the smart dust, not only into liquids, but also, about using it in the air. How would it work in the air?

SAILOR: Really, we’re using the smart dust in three application areas. We’re thinking about putting it into the body for medical monitoring. We’re thinking about putting it into water for monitoring either drinking water, or the quality of seawater, for instance. And the last is to try to identify pollutants in air. And this could be pollutants in the environment, in the air outside, or it might just be used to monitor the quality of air in a building. And the real key is that we’re making these things so small that we can distribute them widely and make them very inexpensively. And the kinds of molecules that we’re trying to target with these little particles in air are things like pollutants, VOCs—so-called volatile organic compounds, things like gasoline or methyl, ethyl chetones is an industrial solvent that we can see with these particles. We also have a big effort looking at chemical warfare agents, and we’ve able to tune the chemistry of these particles so that they can respond very specifically to sarin gas. And so that’s another application.

CURWOOD: Give us a picture of how a detection system could operate in the real world sometime.

SAILOR: These little codes in these little particles will change, and our scanner can pick that up. And so you can imagine putting these things onto a wall in a building and having them, say, change color as maybe a chemical gets into a room that’s something you don’t want to be there. It might be a chemical warfare agent. It might be a toxic chemical, an industrial solvent. Maybe somebody down the hall spills a bucket of paint. Our little particles – if there were, say, vapors in the room – we’ve made some vapor sensors that could respond to a bucket of paint spilled in the room, or gasoline, or diesel fumes. These little particles would start out green and they would actually changes color to red. And you can see that with your eye even, if you want. We usually build systems, little spectrometer systems that can read them and give us s little more information – a level of concentration of the pollutant in the air.

CURWOOD: Michael Sailor is professor of chemistry and biochemistry at the University of California at San Diego. Thanks for taking this time with me today.

SAILOR: Thank you.

[MUSIC: Talking Heads “Warning Sign” MORE SONGS ABOUT BUILDINGS AND FOOD (Sire 1978)]

 

Links

University of California Smart Dust Page

 

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