A WO3-impregnated thin polymer across two closely spaced microelectrod
es is employed as a solid-state CO2 microsensor at 1 atm and room temp
erature. Its function is based on the WO3 transformation to the conduc
ting H. WO by intercalation of released protons from CO2 equilibration
in the polymer. The response to CO2 concentrations is reversible and
linear between approximately 0-16% at approximately 840 kOMEGA per 1%
change over prolonged operations of approximately 80-second switching
time. A dependence on residual water in the polymer is detected but ex
erts no influence on the CO response as long as the polymer is not ent
irely dried out by H2O-free gas.