MIT's 'electronic nose' could dete...(d to detect fish but our nose contains a...)
d to detect fish, but our nose contains arrays of sensors sensitive to various chemicals. Over time, we train ourselves to know that a certain distribution of vapors corresponds to coffee, he said.
In previous work, designed to detect nitrogen oxide (NOx) emissions from diesel exhaust, the researchers created sensors consisting of flat, thin layers of barium carbonate deposited on quartz chips. However, the films were not sensitive enough, and the team decided they needed more porous films with a larger surface area.
To create more texture, they applied the barium carbonate to a layer of microspheres, hollow balls less than a micrometer in diameter made of a plastic polymer. When the microspheres are burned away, a textured, highly porous layer of gas-sensitive film is left behind.
The resulting film, tens of nanometers (billionths of a meter) thick, is much more sensitive than flat films because it allows the gas to readily permeate through the film and interact with a much larger active surface area.
At first, the researchers used a pipette to deposit the barium carbonate and microspheres. However, this process proved time-consuming and difficult to control.
To improve production efficiency, the researchers took advantage of a programmable Hewlett Packard inkjet print head located in the MIT Laboratory of Organic Optics and Electronics. The inkjet print head, like that in a regular inkjet printer, can deposit ink very quickly and controllably. The special gas sensitive inks used in this work were optimized for printing by Amy Leung, an MIT sophomore in chemical engineering.
This allows the researchers to rapidly produce many small, identical chips containing geometrically well-defined gas-sensing films with micrometer dimensions. Patterns, of different gas sensitive inks, just as in a color printer, can be easily generated to form arrays with very little ink required per sensor.
In future studies,
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| Contact: Elizabeth Thomson thomson@mit.edu 617-258-5402 Massachusetts Institute of Technology Source:Eurekalert |
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