In this invention, a mixture of a diazotizing reagent which reacts with nitrous ions to produce a diazo compound, a coupling reagent which couples with {HEAD ~ a diazo compound} to produce {TAIL ~ an azo dye}, and an acid is placed in pores of a transparent porous body to prepare a sensor element 
to produce
In this invention , a mixture of a diazotizing reagent which reacts with nitrous ions to produce a diazo compound , a coupling reagent which couples with { HEAD ~ a diazo compound } to produce { TAIL ~ an azo dye } , and an acid is placed in pores of a transparent porous body to prepare a sensor element
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH