Electrical Characteristics of WO3-Based CO2-Sensitive Solid-State Microsensor

A WO3-impregnated thin polymer across two closely spaced microelectrodes is employed as a solid-state CO2 microsensor at 1 atm and room temperature. Its function is based on the WO3 transformation to the conducting HXWO3 by intercalation of released protons from CO2 equilibration in the polymer. The response to CO2 concentrations is reversible and linear between ∼0-16% at ∼840 kΩ per 1% change over prolonged operations of ∼80-second switching time. A dependence on residual water in the polymer is detected but exerts no influence on the CO2 response as long as the polymer is not entirely dried out by H2O-free gas.