Research On Portable Rapid Detection System Of Pathogen In Sewage From Ships Based On STM32

With people’s growing awareness of marine environmental protection, the problem of the sewage discharge from ship is getting more and more attention by the international community, and its discharge standard is continuously improved under the relevant domestic and international conventions and regulations, Meanwhile, each port state continues to strengthen the inspection of the sewage discharge. However, aiming at the problem of whether the discharged sewage from ship has reached the standard of relevant conventions, each port state does not have a precise and effective on-site rapid detection method, just only to judge roughly by a simple and qualitative traditional checking way. This paper designs a portable rapid detection system of pathogens in sewage from ships based on STM32and microfluidic chip technology, and conducts an on-site and real-time detection on the number of E. coli which is the most representative indicator of the sewage discharge from ship. The specific working contents are as follows:(1) The structural design and production of microfluidic chip. Based on the detection characteristics of E.coli in sewage from ships and the pressure-driven aggregation theory of detection chip, this paper designs a kind of microfluidic chip which is suitable for E.coli’s on-site detection, and then conducts a three-dimensional simulation on the flow channel structure of the designed detection chip by using ANSYS CFX software. Finally, the microfluidic chip with corresponding structure is produced, and a couple of optical fibers after the corrosion are embedded into the PDMS of microfluidic chip in a reasonable manner;(2) The design of laser-induced fluorescence optical detection system and signal amplification and filter circuit. Based on the mechanism of laser-induced fluorescence and the structure principle of each optical device in the optical detection system, the paper completed the structural design of the optical detection system. Then, according to the output signal features of the photomultiplier tube (PMT) in the optical detection system, a signal processing system consisting of a differential amplification circuit, a high pass filter circuit, a low pass filter circuit and a band-stop filter circuit is designed, And then conducting a simulation analysis on each module circuit of the signal amplification and filter circuit with the electronic simulation software Multisim, so that the relevant parameters of each circuit and the models of electronic components are determined. Finally, producing the corresponding printed circuit board;(3) The hardware circuit design in real-time detection system of E.coli in ship sewage and the software program design in the real-time and dynamic detection process of E.coli based on STM32. In the part of hardware design, the real-time detection system for E.coli mainly includes power module design, interactive interface design, data acquisition module design, memories’s expansion design and communication modules design and so on. In the part of software design, it mainly includes the transplantation of real-time operating system μC/OS-Ⅱ and file system FAT on STM32and the specific functions design of each task in the software layer.Finally, this paper conducts the overall detection experiments on the designed real-time detection system of E.coli, and the experimental results show that:the designed portable real-time detection system of E.coli based on STM32can operate stably, and it achieved all the expected functions in the real-time dynamic detection process of E.coli.