• Diatoms become photoluminescent gas sensors

    With their clear silica shells, diatoms would appear to somehow have a photonic purpose.
    Sept. 1, 2007

    With their clear silica shells, diatoms would appear to somehow have a photonic purpose. Researchers at the Università di Napoli Federico II and the Istituto per la Microelettronica e Microsistemi-Unità di Napoli (both of Napoli, Italy) have found one; they have turned diatoms, or at least their shells, into photoluminescence-based gas sensors that can measure the presence and concentration of nitrogen dioxide (NO2), methane, or carbon monoxide in air. They experimented on three types of diatoms, all with micrometer-size macropores, and one with 20 to 30 nm micropores.

    The silica shells were separated from the cell and deposited on a silicon substrate; a 325-nm-emitting helium-cadmium laser was the excitation source. A spectrometer and CCD camera acquired the data. The researchers measured the photoluminescence spectrum in dry air, and then introduced a gas. All the gases induced either an increase or decrease of the magnitude of the dry-air spectrum, but no change in spectral shape (thus the gas has to be known, and only one gas can be sensed at a time). The detection threshold for NO2 in one of the diatom samples reached the sub-parts-per-million level. Contact Stefano Lettieri at [email protected].

    Sign up for Laser Focus World Newsletters
    Get the latest news and updates.

    Voice Your Opinion!

    To join the conversation, and become an exclusive member of Laser Focus World, create an account today!