Aiming at problem of lower sensitivity in low volume fraction gas detecting of normal gas sensor

a measuring method which enhances gas sensing response by compressing target gas is proposed. According to sensing character of compressed gas

volume fraction of the target gas in ordinary sate is obtained. A set of small prototype system is designed for gas compressing and testing

design of each module of system are described

software design and control flowchart are presented. Experimental results of using H2 S as the target gas show this method improves the ability improve ability to detect lower volume fraction

especially improve ability to detect and alarm toxic gas. Fabrication and test of prototype system provide condition for device with higher performance and smaller size

and has high application value.