Miniature Chemiluminescence NO Sensor Based on PIN Photodiode

A miniature chcmilumincsccncc NO sensor is developed using a miniature low-cost PIN photodiodc as the photoelectric detector. Five optoelectronic components of the Si detector and InGaAs detector arc selected to investigate their relationship with the spectral response of NO luminescence and noise. The experimental results show that the 1.2-mm-length rectangular Si detector is the best one with the advantages of a sensitive response, a low dark-current noise, and the lowest signal-to-noise ratio. Moreover, a small optical cavity is designed, small amount of NO luminescence with a volume fraction of 2 x 10(-5) x 10(-4) is measured, and the linearity is 0.9993. The response time of the whole system is approximately 0.13 s and the sensor weight is less than 50 g. Thus the proposed sensor is very suitable for the online monitoring of NO gas in the industrial pollution source.