Smoke sensor with overcoming of humidity cross-sensitivity

The influence of the environmental humidity on the sensors based on a thin-film gamma-Bi2O3 is investigated. It is shown that relative humidity affects smoke sensing performances. To overcome the humidity cross-sensitivity, a new version of high sensitive smoke sensor with corresponding alterations in its design is proposed. The optimal operation mode when humidity cross-sensitivity becomes negligible and the smoke sensitivity reaches its maximal value is revealed. The time characteristics of the sensors under influence of the various concentration air-smoke mixtures are studied. A smoke detector processing circuit based on the considered smoke sensor sensing element is proposed. It is shown that such a smoke detector is able to operate reliably under low concentration of smoke and high relative humidity conditions. (C) 2003 Elsevier Science B.V. All rights reserved.