chemical of interest in a system application_number US 24324708 A description in the following detailed description of the preferred embodiments reference is made to the accompanying drawings which form a part hereof and within which are shown by way of illustration the practice of specific embodiments of chemical detection sensors and systems it is to be understood that other embodiments may be utilized and that structural changes may be made and processes may vary in other embodiments fig1 illustrates one embodiment of a chemical sensor 10 the sensor 10 includes a reference thermocouple 12 and a first experimental thermocouple 14 adjacent the reference thermocouple 12 the basic functioning and structure of thermocouples are known to a person having ordinary skill in the art so background information on thermocouple structure and basic function will not be covered in depth here the first experimental thermocouple 14 forms part of a first detector assembly 16 including both the first experimental thermocouple 14 and a first reactive component 18 attached proximate to the first experimental thermocouple 14 at a first joint 20 in the embodiment shown in fig1 the sensor 10 is located in a closed system 22 defined at least in part by an enclosing structure 24 the sensor 10 is preferably very small so that it does not interfere with any processes or functioning of the system 22 for example the width of the first experimental thermocouple leads preferably ranges from about 3 u00d7 10 u2212 3 inches to about 5 u00d7 10 u2212 3 inches and most preferably is about 3 u00d7 10 u2212 3 inches shown as length u201c w u201d in fig1 the preferred small size range also allows for.