A gas sensor and method thereof are provided. The example gas sensor may include first and second electrodes formed on a substrate, a carbon nanotube connecting the first and second electrodes on the substrate, a light source disposed above the carbon nanotube and an ampere meter measuring current flowing between the first and second electrodes. The example method may be directed to identifying a gas, and may include 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.