溶解氧传感器设计及测量系统

【作者】 王健；

【导师】 唐慧强；

【作者基本信息】 南京信息工程大学 ， 电子信息（专业学位）， 2021， 硕士

【摘要】 溶解氧和pH值是衡量水资源品质的重要参数,同时也是判断水体自净能力的重要指标。方便、准确、快速地测量水中溶解氧含量和pH值大小对环境监测、工农业生产均具有重要意义。本文在分析电化学基本原理的基础上,设计了两电极型极谱式溶解氧传感器,并详细介绍了传感器的制作过程,包括传感器材料的选取、传感器两电极的研制以及电解液的配置等。通过试验研究了工作电极表面积和辅助电极材料纯度对传感器性能的影响,以及透氧膜厚度与响应时间的关系,分别在零氧和饱和氧两种条件下验证了传感器的稳定性。为验证传感器的实际使用性能,设计了具有信号放大、采集、数据存储等功能的硬件处理电路。该系统以低功耗的STM32F103RCT6为主控芯片,PT1000为测温元件,结合模数转换芯片ADS1232实现高精度测量。设计四线制铂电阻测温电路获取温度数据,加入算法对溶解氧及pH值的测量提供温度补偿,可以有效提高系统检测的准确性。使用多点标定方法分别对溶解氧传感器和pH传感器进行标定,并同相关高精度仪器进行数据对比,分析系统测量精度。经调试运行,该系统测量温度的精度达到±0.05℃,pH值测量的精度为±0.05,自制溶解氧传感器在零氧环境中绝对误差不超过0.5ug/L,饱和氧环境中绝对误差不超过0.5mg/L,满足设计指标。更多还原

【Abstract】 Dissolved oxygen and pH value are important parameters that measure the quality of water resources,as well as important indicators to judge the self-purification ability of water bodies.It is of great significance for environmental monitoring,industrial and agricultural production to measure the dissolved oxygen content and pH value in water conveniently,accurately and quicklyIn this paper,based on the analysis of the basic principles of electrochemistry,we designed a two-electrode polarographic dissolved oxygen sensor,and introduced the production process of the sensor,including the selection of sensor materials,the development of the two electrodes of the sensor,the configuration of electrolyte and so on.The effects of the surface area of the working electrode and the purity of the auxiliary electrode material on the performance of the sensor,as well as the relationship between the thickness of the oxygen permeable membrane and the response time,were studied through experiments.The stability of the sensor was verified under the conditions of zero oxygen and saturated oxygen respectively.In order to verify the actual performance of the sensor,a hardware processing circuit with signal amplification,acquisition,data storage and other functions is designed.The system uses the low-power STM32F103RCT6 as the main control chip,PT1000 as the temperature measurement element,and the analog-to-digital conversion chip ADS1232 to achieve highprecision measurement.A four-wire platinum resistance temperature measurement circuit is designed to obtain temperature data,and an algorithm is added to provide temperature compensation for the measurement of dissolved oxygen and pH value,which can effectively improve the accuracy of detection.The dissolved oxygen sensor and pH sensor are calibrated by multi-point calibration method,and the data are compared with related high-precision instruments to analyze the measurement accuracy of the system.After debugging and running,the accuracy of the system for temperature measurement is ±0.05℃,and the accuracy of pH measurement is ±0.05.The absolute error of the self-made dissolved oxygen sensor in a zero oxygen environment does not exceed 0.5ug/L,and the absolute error in a saturated oxygen environment does not exceed 0.5mg/L,which satisfies the design index.更多还原