BACKGROUND: Northeastern University researchers have built a portable, cell-phone-sized device that can quickly detect tiny amounts of contaminants in the air from natural disasters, industrial accidents, or terrorist attacks. Slated to become commercially available in the next year, the device uses some of the same technology used in cell phones and plasma televisions to create a smaller, cheaper, and lighter portable unit for performing chemical analysis, instead of bulky lab equipment requiring thousands of watts of power.
HOW IT WORKS: The microplasma device converts samples taken from the air into very small plasmas and then measures the unique set of light colors (wavelengths) that are subsequently emitted by the electrically charged atoms and molecules. A cell-phone chip supplies the radio-wave energy needed to create the microplasma. Instead of beaming those radio waves to the outside world, that energy is concentrated inside the unit, in a microscopic gap -- about one-half the width of a human hair -- within a thin ring of gold. All that energy in so small an area causes the collected gases in the gap to become what scientists call 'ionized': the electrons are stripped from the gas atoms. The device watches the light emission from the plasma to determine if there are any contaminants in the air. It can do this because every chemical element has a distinct "signature" in the form of what kind of light it will emit under those circumstances.
WHAT ARE PLASMAS: A plasma is essentially electrically charged gas, consisting of free-moving electrons and ions (atoms that have lost electrons). Applying a surge of energy -- with a laser, for example -- knocks electrons off gas atoms, turning them into ions and creating a plasma. Unless this energy is kept high, however, plasmas will recombine back into a neutral gas. On Earth, we are familiar with the ordinary states of matter: solids, liquids and gases. But in the universe at large, plasma is by far the most common form. Plasma in the stars and the space between them makes up 99 percent of the visible universe. Because plasmas are conductive, respond to electric and magnetic fields, and are efficient sources of light, they are valuable in many different applications. The term "plasma" was applied to ionized gas for the first time in 1929 by Irving Langmuir, an American chemist and physicist.
The Institute of Electrical and Electronics Engineers, Inc., and AVS and the Science and Technology Society contributed to the information contained in the TV portion of this report.