Measuring Instrument Of Carbon Dioxide Based On Infrared Sensor

With the progress and extensive development of technology, the greenhouse gas constituted of the CO₂ has an increasing effect on agriculture production, daily life and natural environment. Meanwhile, the CO₂ needs to be detected and controlled quantificationally in the medical care, automobile and mine etc.According to the development of the infrared detection technology at homes and abroad now, the development of detecting the gas concentration by means of the absorptive method is not mature. The price of the same products is expensive abroad and the after-sales service is inconvenient. Moreover, the current demand in domestic market for these products is very big.According to Beer - Lambert theorem and the infrared absorption principle, we adopt the infrared sensors in the CO₂ concentration measurement device, and the CPU uses MSP430 which has built-in AD transform function to make the device have the features of low power consumption, wide measuring, high sensitivity, strong anti-interference ability, good selectivity and so on. Adopting double channels infrared sensor,which can eliminate the effects on the measurement effectively due to the change of external environment condition. At the same time, it improves the stability and life of light source by using the pulse to control light source and provide 50Hz light flashing frequency. By setting a protection resistance in RS485 serial communication circuit to improve the work stability of the measuring device. During the experiment, it takes the advanced Model 400 device maybe in America as the reference instrument, and get many experimental data. It is convenient to analysis the experimental data scientifically and reasonably. Finally, we analysis the measure datas by using the Curve Fitting Tool in the MATLAB tool and obtain well fitting effect and make the coefficient of determination above 0.98. It provides offers the accurate quantitative data for gas sampling analysis and continuation detection on line in our county. Meanwhile, the search for CO₂ offers the foundation for further research localization, multi-parameter gas detection instruments.