A chemical concentration modulation sensor for selective detection of airborne chemicals

Abstract A method for selective detection of airborne chemicals based on concentration-modulated signals is described. A variable energy source ( e.g. , a heated filament) causes a modulated chemical reaction in a flowing gas stream, and a chemical sensor monitors the resultant modulated concentration signal. A parameter that is specific for a particular chemical species ( i.e. , a pseudo-activation energy) can be determined. Because this parameter is unique for a particular chemical and set of operating conditions, devices based on this method offer selectivity in sensing chemical vapors. A single detector capable of selectively identifying a large number of chemicals is possible using this approach.