【摘要】 叶绿素a原位监测在海洋生态系统健康评估与碳循环过程研究中有重要价值。设计了一套原位叶绿素a的精密测量方案,以交流调制检测为基本方法,开发了交流模拟放大通路,使用开关检波系统完成最后的检波。噪声测试实验表明系统电流分辨力达到186.27 fA。通过仿真和对比实验证明了开关检波系统具有很强的频率选择特性,在系统噪声抑制方面起重要作用。标准叶绿素标定实验表明在0～30μg/L内系统线性度良好,用直线拟合R2=0.998 5,检测灵敏度S=0.008 1μg/L,满足使用需求。更多还原

【Abstract】 The in-situ monitoring of chlorophyll-a has become more and more important in the health assessment of marine ecosystem and the study of carbon cycle.This paper proposes a high precision in-situ system for detecting chlorophyll-a.The system uses AC modulated detection as the basic method;an AC analog amplification channel is developed and a switch demodulation system is used to complete the final detection.Noise analysis experiments indicate that the minimum current resolution of the system reaches 186.27 fA.Simulation and the comparative experiments prove that the switch demodulation system has strong frequency selectivity and can suppress noise efficiently.Calibration experiments of chlorophyll-a show that the system has good linearity in the range of 0~30 μg/L with R2=0.998 5 and has the minimum resolution of 0.008 1μg/L,which meets the requirement of applications.更多还原