Approaches to overcome the cross-sensitivity of a sensor include: (1, materials engineering) tune the chemistry of its recognition element to enhance its selectivity for the analyte; (2, sensor array) include additional sensors harboring different recognition elements, to construct a sensor array whose response pattern provides more information about the gas; (3, pre-filtering) filter the gas before it is exposed to the sensor, to prevent the interferent from reaching and interacting with its recognition element. Approach (1) is most fundamentally difficult. Approach necessitates machine learning algorithms to interpret the response pattern . In approach (3), a filter that selectively (physi-or chemi-)adsorbs the interferent -such as a zeolite membrane -will eventually saturate with gas and thus require regeneration or replacement .