Patent ID: 7918989

Claim:
A method of measuring a gas, comprising: measuring a first current responsive to a first applied voltage during a first mode of operation; comparing the first measured current with a plurality of first index current values to obtain a first comparison result, each of the plurality of first index current values associated with one of a plurality of gases; measuring a second current responsive to a second applied voltage during a second mode of operation; comparing the second measured current with a plurality of second index current values to obtain a second comparison result, each of the plurality of second index current values associated with one of the plurality of gases; and determining gas characteristic information based on the first and second comparison results, wherein the first and second currents are associated with one or more carbon nanotubes, the first applied voltage is applied directly to a carbon nanotube, the second applied voltage is applied to a light source, the second measured current corresponds to a current generated in a carbon nanotube responsive to light radiated from the light source powered by the second applied voltage, the gas characteristic information includes a type of a gas and a concentration of the gas, the first mode of operation is a dark mode wherein no radiated light affects the first measured current and the second mode of operation is a light mode where radiated light affects the second measured current, and the first voltage and the second voltage are applied simultaneously.