Abstract:A CO2 concentration monitoring system targeting greenhouse application was designed, which included sensor nodes, CO2 concentration regulation node, wireless communication and PC terminals. A remote real-time CO2 concentration measurement was realized by using an infrared CO2 model S300 as the core model in sensor node. Environmental information derived by sensor nodes was transmitted to the PC software panel based on LabVIEW through wireless sensor networks. Received signal strength indication (RSSI) was sampled in transmission to ensure link quality and extend the service lives of sensor nodes by reasonably adjusting the transmission power. The designed and fabricated sensor node was calibrated and characterized by the standard CO2 samples distributed under laboratory conditions. The experiment results indicated that the limitation of detection of the selected sensor was lower than 5×10-5. The fluctuations for the long-term stability measurements on a 3×10-4 CO2 sample and a 6.5×10-4 CO2 sample were less than 2.6%. This designed monitoring system was deployed in the Guoxin picking garden in the town of Sheling, Shuangyang District, Changchun City, Jilin Province, and the field experiment was carried out in a solar greenhouse whose area was 640m2. The desired CO2 concentration in greenhouse was set to 8×10-4, the fluctuation range under controlled CO2 concentration was nearly (8±0.42)×10-4.The designed sensor node had advantages, including miniaturization, cost-effective and high precision, which realized intelligent management, remote synchronization of greenhouse factors and smart regulation of CO2 concentration in greenhouse.