科技的进步加快了海洋的开发，但随之而来的是海洋的污染也日益严重。人们从海洋中获得资源，但被污染的资源最终会伤害人类本身，所以海洋环境监测尤为重要。传统的方法如遥感技术、采样测量有或多或少的缺点，为了更准确便捷地监测海洋环境，本文研究了一种原位叶绿素a荧光传感器来实时监测海水中叶绿素a的浓度，进一步反映浮游植物的含量，为海洋的开发和治理提供参考依据。

基于荧光测量原理，设计了一套低功耗、小体积、高精度、长使用寿命的海水叶绿素a荧光传感器。选择了450nm的蓝光发光二极管作为光源，PN型光电二极管作为光敏元件，搭建了传感器的光路，并根据所选器件的性能进行了电路设计，主要分为四个模块：电源模块、LED驱动模块、信号采集模块、信号处理模块。工作机制为蓄电池为整个仪器供电，TM32F103C8T6微处理器产生一个70Hz的交流信号驱动LED灯，产生蓝光经透镜汇聚后照射到水体中，水体中的叶绿素a被激发从而产生荧光，荧光透过光学窗口经过透镜汇聚，再经过滤光片过滤后被光电二极管接收，转换为电信号，随后经过放大、滤波、AD采样转化为数字信号，最后传输到单片机中。单片机控制着整个仪器的工作，同时也通过RS485与上位机进行通信。此时接收到的荧光信号就能间接代表叶绿素a的浓度。随后，在Altium Designer软件中进行PCB板设计，按照仪器的需要定制PCB板，并制备出完整的PCB板。

实验结果表明，仪器检测到的荧光信号与叶绿素a浓度之间有很好的线性关系，在规定区间内相关系数R平方能达到0.99以上；仪器具有很低的检测限，能达到0.01ug/L；仪器具有较低的功耗，正常工作时功率小于1W，能满足长时间原位在线检测。将检测结果与国外先进仪器和国家标准法进行对照，都能表现出很好的相关性，因此海水叶绿素a荧光传感器是成功的，能够应用在实际的海洋环境监测中。

Advances in science and technology have accelerated the development of the oceans, but the pollution of the oceans has become increasingly serious. People get resources from the oceans, but the polluted resources will eventually harm the human beings. Therefore, marine environmental monitoring is particularly important. Traditional methods such as remote sensing technology and sampling measurement have more or less disadvantages. In order to monitor the marine environment more accurately and conveniently, this paper studied an in situ chlorophyll a fluorescence sensor to monitor the concentration of chlorophyll a in seawater in real time, further reflecting The content of phytoplankton provides a reference for the development and management of the ocean.

Based on the principle of fluorescence measurement, a set of seawater chlorophyll a fluorescence sensor with low power consumption, small volume, high precision and long service life was designed. A 450nm blue light-emitting diode was selected as the light source, and the photodiode was used as a detector to build the optical path of the instrument. The circuit design was carried out according to the performance of the selected device. It was mainly divided into four modules: power module, LED driver module, and signal acquisition. Module, signal processing module. The working mechanism is that the battery supplies voltage to the whole instrument. The TM32F103C8T6 microprocessor generates a 70Hz AC signal to drive the LED lamp, which generates blue light to the water sample. The chlorophyll a in the water sample is excited to generate fluorescence, and the fluorescence passes through the optical window. After being filtered by the filter, it is received by the photodiode, converted into an electrical signal, and then converted into a digital signal by amplification, filtering, and AD sampling, and then transmitted to the microprocessor. The microprocessor is connected to the host computer through RS485, and also controls the operation of the entire instrument. The fluorescent signal received at this time can indirectly represent the concentration of chlorophyll a. Then, in the Altium Designer software, the PCB board design is performed according to the required circuit, the PCB board size is determined according to the needs of the instrument, and a complete PCB board is prepared.

The experimental results show that there is a good linear relationship between the fluorescence signal detected by the instrument and the concentration of chlorophyll a. The correlation coefficient R can reach 0.99 or more in the specified interval; the instrument has a very low detection limit and can reach 0.01ug/L. The instrument has low power consumption and the power is less than 1W during normal operation, which can meet the long-term in-situ online detection. Compared with foreign advanced instruments and national standard methods, they can show good correlation. Therefore, the seawater chlorophyll a fluorescence sensor is successful and can be applied in actual marine environment monitoring.

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