| CPC G01N 27/4141 (2013.01) [G01N 27/308 (2013.01); G01N 27/4146 (2013.01); G01N 27/48 (2013.01); G01N 33/004 (2013.01)] | 20 Claims | 

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               1. A sensor comprising: 
            a conductive region in electrical communication with at least three electrodes, 
                the electrodes insulated and separated from each other with a dielectric layer having an adhesion layer thereon, the electrodes including source-drain electrodes, and 
                the conductive region including a conductive material and an in situ activated redox-active selector comprising a metalloporphyrin, the metalloporphyrin immobilized with respect to a carbon nanotube in the conductive material by a ligand that is covalently bound to the carbon nanotube, the redox-active selector responsive to an applied gate voltage that transiently reduces the redox-active selector such that the in situ activated redox-active selector is configured to bind an analyte more readily in a first redox state compared to a second redox state, the sensor having a selectivity to ppm levels of carbon monoxide in air and being operational in air. 
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