Gas detector with controlled selectivity, has source applying variable-frequency voltage to sensor, to measure its electrical conductivity

摘要

A circuit (20) includes a source (21, 22) producing variable frequency voltages, which are applied to the sensor (11) whilst measuring its electrical conductivity. An Independent claim is included for gas detection and computer-readable product for corresponding programming. Preferred Features: Volumetric and surface conductivities of the gas sensitive material of the sensor are measured. Frequencies from and including zero are produced. A DC and an AC source are combined in the circuitry. Switching between various frequencies is included, with a switch and controller. A programmed computer controls application of variable frequency voltages and/or conductivity measurement. The sensor comprises a gas-sensitive ceramic. The sensor is heated. A detector measures power supplied to the heater.