A portable rapid detection instrument for four harmful gases which involve indoor formaldehyde

ammonia and benzene is designed. The instrument is designed with a novel electrochemical sensor to get value of initial concentration of corresponding gas and new type high-precision signal processing circuit based on FPGA.Combine indoor ambient pressure

temperature and humidity conditions

correct value of initial concentration

and the audible and visual alarm begin to work when concentration exceed the standard. The instrument has advantages of fast detection speed

high precision and easy to carry

and provide a simple and reliable method for public to real time and quickly detect indoor air quality.