1. THIN FILM GAS SENSORS Chemical sensors are important to all aspects of modern life. They Provide information about chemical substances needed by instruments. They can protect environment, assist in medical diagnosis and life support systems, provide safety in homes, offices and transportations, and help automate laboratory and industrial operations.

2. Working Principal of Chemical Sensors The electrical conductivity of semiconductors is sensitive to the gaseous ambient. The semiconductor sensor is based on a reaction between the semiconductor and the gases in the atmosphere, which produces a change in the semiconductor conductance. Metal-Oxide sensors are the most promising materials for film-based semiconductor sensors because they do not change their form upon heating in air. As the process responsible for the change in conductance takes place at the boundary between the gaseous and the solid states, special attention is needed to the surface quality of the oxide. Because of the advantageous proportion of surface to volume, a thin film of the metal-oxide will be optimum arrangement for a sensor.

3. FEATURES Chemical sensors Photo sensors Pressure sensors Use at high temperatures and harsh environment Small size Low cost

4. TYPICAL APPLICATIONS Environmental cleanup Industrial process control Emission monitoring Home and workplace safety Application in Petrochemical Industrial The most common gases monitored include; Hydrogen sulfide Sulfur dioxide Carbon monoxide Methane and flammable hydrocarbon

5. Gas Mixing Setup