Design And Realization Of DO Sensor Based On Fluorescence Characteristic Of Oxygen Sensor Membrane

A novel preparation technique for oxygen sensor membrane is proposed based on the pouring method, since the current dissolved oxygen(DO) sensors based on fluorescence characteristic have the shortcomings of high cost, complex preparation of the sensor membrane, etc. The quality of the sensor membrane is examined according to the results of eyeballing, microscopic examination and the light transmission features. Based on it, a unique oxygen sensor probe with its end face at an angle of 45 degrees is designed, and the DO is measured with high precision. The contents are concluded as follows:1、The typical DO detection techniques and their development status are summarized. The working principle and the technical advantages of DO sensors based on fluorescence characteristic are discussed and the preparation technique of DO sensor membrane is emphatically described.2、The mechanisms of fluorescence and quenching are studied. By detecting the intensity of fluorescence, a unique oxygen sensor probe with its end face at an angle of 45 degrees is designed to reduce the interference from bubbles. To improve the stability of the excitation light source, a PWM constant-current drive circuit is designed. The noise characteristic of the photoelectric detection section is evidently improved by employing the AC amplification, the filter and shape circuits.3、he oxygen sensor membranes with different ratios of chemical components have been prepared. The excellent one can be indentified by considering the results of eyeballing, microscopic examination and its light transmission features. Then, the influences of excitation intensity, circuit parameters, the temperature and PH value of the water on the intensity of fluorescence emission from the sensor membrane is investigated. Through optimization of the parameters discussed above, the DO detection precision is increased. Our experimental results show that the sensor can accurately measure the oxygen concentration of the water under test in a range of 1-18mg/L, with the measurement precision of 0.17mg/L, the detection limit of 0.8mg/L and the response time <40s. Such a DO sensor may have a good application prospect in many areas, such as industrial and agricultural production, water quality monitoring and aquaculture.